Post 602 by Gautam Shah 



These are rules per ISO, and also better methods of writing measurements on DESIGN RELATED DRAWINGS. These apply to manual drawings and also CAD representations.

All decimal numbers must be preceded by a zero if no other digit exists. e.g. 0.121 (and not as .121 )

No thousand or hundred markers are to be used, e.g. 1000 (and not 1,000), but where large number of digits are involved a blank or space (equal to 1 digit or not less than ½ digit in width) may be used as a separator, in place of a marker. However, where only four digits are used no space as a separator need be provided. e.g. 100 000, 10 000 or 1000 (but not 1 00 000 or 1 000).

▪ For Length units recognized measures are km / m / mm which may if at all required must be in small letters. For example architectural plans have nearly all measures in mm, so the mention of mm should be avoided. However, in the same drawing if weight or volume or such other measures are to be indicated, then identifiers for such units may be indicated.


Architectural drawings nominally have dimensions of maximum 5 digits (for mm ) unless a detail requires indicating a fraction of a millimeter, signifying measures up to 99999 mm or 99.999 mts (-but unit identifiers are not to be used). Plans larger then 99mts sizes are considered of Map Category.

▪ Full names of units even when these are named after a person, are written in small letters: ampere, volt etc., with the exception W for watt and J for Joule.

▪ For liquid measure (Litre) however lt may be written as Lt (to differentiate between 1 and l ).

▪ Plurals of measures need not be used. (kms, mts, kgs).

Point or Full stop for abbreviation may not be used, for example as in m.g. or ml.

▪ Where cubic or square measures are to be shown: 3m3 = will mean three cubic metres and not 33 i.e. 3 x 3 x 3 = 27cmt.

▪ Following common units are acceptable

Length  mm m  km (all 1000 factored=103)

Weight  gm  kg  mt or t (all 1000 factored=103)

Liquid  mlt  Lt  klt (all 1000 factored=103).


Where traditionally only one unit is accepted, and if there are no chances of ambiguity, the measure nomenclature (mm, km, gm etc.) may not be mentioned. (E.g. cloth width = 1.200). If in one sheet of drawing (or a document) only one scale and one mode of measure are used, the nomenclature may be mentioned as a general instruction for the drawing.

Where drawings or details are likely to be graphically reduced or enlarged in processing / copying, a graphical scale preferably showing 100 mm bar may be shown. If 100 mm size is not suitable due to micro reduction or macro enlargement, suitable multiples of 100 mm for upwards scaling and 10x fractions of 100 mm for downwards scaling maybe used.



When both mt & mm are used on drawings, it will be less confusing if the dimensions are always written to three places of decimals, i.e. 3.450. No unit symbol need be shown unless a lesser number of decimal places are used; i.e. 3.450 or 3.45 m and under some circumstances 3.5 m, are all correct. Of the options, 3450 and 3.450 both are preferred. Where no ambiguity can arise, symbols may be discarded, according to following rules:


▪ Whole numbers indicate mm

▪ Decimated fractions to three palaces of decimals indicate m (and also by implication, mm)

All other dimensions or measures must be followed by the unit symbol.

▪ Where dimensions refer to different types of measures (lengths, weights, temperature etc.), preferably all units should be indicated or all units other than the major one should be indicated.

▪ Main dimensions and the tolerance (fitments, limits, margins etc.) etc. should be in the same unit system.

▪ Where main dimensions are accompanied by + or – range, both should be in the same unit.


All architectural drawings follow ISO modular preferences and these are as follows:

ISO’s Four Preferences for Modular Coordination:

       First Preference            30 cm or 300 mm = 12″

      Second Preference      10 cm or 100 mm = 4″

      Third Preference           5 cm or 50 mm = 2″

      Fourth Preference        2.5 cm or 25 mm = 1″

First Preference is favoured by the building materials’ industry. Plywoods and other wood products are available in modules of 300 such as 600, 900, 1200, 1800, 2400 etc. Large buildings are designed with 300 as the modular measure. But, for smaller spaces such as Bedrooms, toilets, second preference of 100 is used as a module.

Second Preference is considered to be the most appropriate one for Building components and Planning. Glazed Tiles are available in multiples of 100 mm, with sizes like 100 x 200, 200 x 200, 200 x 300 etc., and also in sizes such as 150 x 150, 150 x 200 etc. as a carry over from the old system. Fabrics have widths of 600, 900, 1000, 1200, 1800 etc. When we order Windows or Doors the width x height are measured in 100 mm increments.

Third and Fourth Preferences are more preferred for objects smaller then 300 sizes. These preferences are not to be used for basic object sizes of more than 300, unless there are strong economic or functional reasons for doing differently.





Post 427 ⇒   by Gautam Shah 


There was a time when all things were measured with comparison to the body and figured with numbers. The numbers were fingers such as Five, Ten or Twenty, or hex multipliers like Six or Dozen, and easily divisible Octet series of 4, 8, 16, 32. Different regions followed own measure numbering system. Varied measure numbering systems created problems like lot recognition and commercial pricing for the lot. To compound the problem, the monetary unit fractioning was equally varied.


The French revolution helped select a ‘scientific’ digital system. It offered 7-10 fractions @10X. The system created utter confusion as to who (which trade) should follow which of the units. The problems of preferring few select units increased manifold, when other countries adopted the Metric digital format but with different set of units. As countries (mainly Spanish colonies in Latin Americas) began to use Metric digital format, with different preferred units, the need for rational and common units became pronounced.

Bronze wool weight of 14 lb (6.4 kg) (1550–1600) stamped with the Royal coat of arms. (Victoria and Albert Museum) Wikipedia Image by David Jackson

There were few other problems with digital units @10X . The digital (time) hour of 1/10 or 1/20 part of the day, or minute to second relationship (@10X) was not acceptable to sailors and astrologers, using compass fractionated into 360 degrees, arcs, minutes and seconds. This had to be rolled back to the original method.

A measuring for volumes of liquids in units of cups, fluid ounces, and milliliters.

Before and soon after World War II, several conferences helped resolve the issue of preferred units of measurements. SI (Système International d’Unités) first recognized, Three units 1000 factored apart, in every series (e.g. km-mt-mm). These were either too large or small for practical applications. A widely spaced measurement system was not amenable to unit formation for processes like planning, design, production, transportation, fabrication or execution, etc. So ISO (International Standards Organization) devised a practical modular system of dimensions known as ISO Modular Preferences. Most National Standards (including Indian Standards) are recommending and enforcing the same for various products and processes.

Imperial measurement standards At Greenwich

Before these were recognized and accepted, there were practical units of measure modulations. For examples plywood and other sheet materials were produced in 4 / 5 Ft widths. Tiles were available in 6 /8/12 inch squares. Foot (12 inches ) was the most popular module and was accommodated in the new order. This was done for wider acceptance and to achieve a gradual changeover.

Module – grid based plan

ISO’s Four Preferences for Modular Coordination:

FIRST PREFERENCE (300 mm = 12 inches) This is favoured by the building materials’ industry. Plywoods and other sheet products are available in modules of 300 such as 600, 900, 1200, 1800, 2400 etc. Large buildings are designed with 300 as the module. But, for smaller spaces such as Bedrooms, toilets, second preference of 100 is used as a module.

SECOND PREFERENCE (100 mm = 4 inches ) This is considered to be appropriate one for Building components and Planning. Glazed Tiles are available in multiples of 100 mm, with sizes like 100 x 200, 200 x 200, 200 x 300 etc., and also in sizes such as 150 x 150, 150 x 200 etc. as a carry over from the old system. Fabrics have widths of 600, 900, 1000, 1200, 1800 etc. When we order Windows or Doors the width x height are measured in 100 mm increments.

THIRD PREFERENCE (50 mm = 2 inches) and FOURTH PREFERENCE (25 mm = 1 inch), are suggested for objects smaller then 300 sizes. Though these modules are not to be used for basic object sizes of more than 300, unless there are strong economic or functional reasons for doing differently.

Tatami as the module for planning of Japanese houses

There are many products where smaller modulation or variations are desirable such as Garments and Shoes. ISO Modular Preferences, do not consider the variations in naturally available materials. Furniture, fittings and fixtures designed with ergonomic profile or serving anthropometric, inconsistencies have no specific accommodation in this system.

Grid for ceiling

ISO is a modular system to form a grid or matrix for macro planning and in that sense takes a superior position. Components and parts are expected to fit in the system. As a result, work-sizes of components and assemblies should be determined by taking into account space for joint and allowance for tolerances.

Geodesic Hex grid Climatron Missouri Botanical Gardens



Post 421  by Gautam Shah 


During pre-medieval periods trade with distanced lands was managed by shippers and caravan masters. These agents conducted the business through the holistic (piece or item) value of the goods, rather then through its measures. This system of commerce changed, in medieval age when many European nations established their own trading posts in colonies across Asia, Africa and American continents. The colonists bought goods at the trading posts, transited and sold in their own country. This was mainly conducted in measure traditions of their mother lands.


Caravan outside Morocco

The European nations, each had distinctive measure systems. The measure systems of lengths, weights or volumes, each had incomparable units, and their subfractions were illogical. These problems were already realized, but now with increased colonial trade, as it caused vast problems. The current political leaderships (Royals) were not capable of solving it.

Sea Trade in Europe

With the onset of Industrial age, the trade, transit and conversion of raw materials, became closely interrelated. Natural raw materials passed through several processes, spread across many nations, to become vast variety of finished products. During the conversion the applicable measure systems also changed. For example, Cotton bought on volume basis, was converted into fabric -sold by lengths, and dresses -sold by numbers. Metal ore is mined in volumetric measure, transported by its weight measure, bought for its yield rate value, refined into ingots for weight measures, rolled into metal sections to be used for their strength aspect.

Colonial post at Salem India

● The transition to common measures systems developed at many fronts. Arabic numerals (actually of Indian origin) became common in Europe, and began to replace the Roman numbers, during the late Middle Ages (about 1500). This made decimal system possible (after Simon Stevin, a Flemish mathematician, in 1585, showed in his book ‘De Thiende’, how fractions could be expressed in decimals.) Vicar, Gabriel Mouton, St. Paul’s Church, Lyons, France, proposed a decimal system of measurement in 1670. Bishop of Autun, also known as Talleyrand was the political sponsor of weights and measures reforms in the French Revolutionary National Assembly. 1790, in the midst of the French Revolution, the National Assembly of France requested the French Academy of Sciences to “deduce an invariable standard for all the measures. Larger and smaller multiples of each unit were to be created by multiplying or dividing the basic units by 10 and its powers. France made its use compulsory in 1840.

10X divisioned clock of French Metric system

Raw materials and Finished products’ are misleading terms for goods. A finished product is a raw material for some other process. Raw materials procured in a linear, square, volumetric, weight or liquid measures get processed into a different ‘measure’ entity. For products transiting from one measure phase to another, a persistent dimensioning system is very advantageous. Consistency of dimensions allows use of standard tools, equipments, plants and technologies. The dimensional consistency, if properly recognized and supported, can rationalize the conversion processes, storage, handling, and waste management.

Ship Batavia –International trade

Steam Engine and Ship

In the Post Industrial Revolution period, trade and industry all over the world recognized the need for a Universal Dimensioning Discipline. At that time better coordination was also required for conversion and transmission from old measurement systems to any new system of measurements. First worldwide understanding emerged in the adoption of SI as the Universal Measure System.

Kuantan Port Yard Container modulated units

Organisation internationale de normalization or International Organization for Standardization would have different acronyms in different languages. Its founders decided to give it a short, all-purpose name. They chose ISO derived from the Greek isos, meaning equal. ISO is a voluntary, democratic and non governmental organization for International Cooperation for Standardization. SI = Systeme Internationale stand for Universal Measure System and it is now accepted by nearly all countries of the world.

Universally agreed parts

SI Recognized Measures: The SI system recognizes three sets of measures in each of the major categories. There is a 1000-factored gradation.

            The ISO Recognized Measures are:

            Length:           mm     mt        km

            Weight:          mg      kg        T

            Volume          ml        Lt         kl

All other measures such as centimeter cm or gram gm are not to be used.



Post 404 – by Gautam Shah 



A professional or an experienced person effortlessly reads and perceives information as presented in variety of documents. An experienced person interprets the information about measures as to what do the pure numbers or lengths, widths, heights, weights, capacities mean. Professional can further interpret the measures into 3D manifestations of objects. For a professional it is easy to transcend from 2D orthographic images to 3D spatial realizations, even while one of it being not physically present. It is often called capacity to read a plan (in armed forces, the contoured survey or flat satellite images) and mentally invest the quality of objects.


A good designer is trained to visualize the spaces with environment, people and other happenings. A designer invests a 2D (plans, sections, elevations) or 3D (isometric, Axonometric, perspectives) images with referencing orientations of gravity, sun, magnetism etc. Sensing an event in a time continuum through a 2D or 3D image creates animation. Till a century and half ago this was simply mental realization and for very few visualizers or dreamers. Modern computers aided tools make it very fast, objective and accurate.


All such references, calibrations, realizations or visualizations, however accurate, encompassing and well made, cannot conform or recreate the entity like the original. This is the reason why designers want models, mock ups, or pilots.

Architectural scaled model

We also experience objects through the sensory affectations like light, colour, sound, temperature, smell, pressure, etc., as caused to our body. But, such affectations are very subjective, and not accountable to any universal system of measurements. We can, however, emulate these affectations as equivalent physio-chemical-electrical changes in our body or outside of it and measure the ‘scale’ of sensory affectations. For example we measure the temperature as it affects the mercury, sound as a vibration, and so on.

Scaled Model testing

Our faculties of perceptions have inherent limitations. We see up to a certain fineness and distance, and listen to sound within 20 to 20000 Hz. We need to scale the measurements that are beyond our range of perception. We also need to not only scale but convert perceptions to suit the recording media and its size scale (width of tape, size of paper, capacity of CD or transmission bandwidths). So design professionals, scientists etc. deal with many entities as they really exist (in original measures), and also in their scaled or converted presentations. Designers are trained to manipulate, arrange, or compose both types of presentations. And they do achieve results that are equal to real size forms.


A graphical representation is metaphoric or symbolic form of the original. Graphical representations are difficult to deal, but with frequent exposure, one gains the proficiency to automatically interpret the conveyed information, as if it is the real happening. Such proficiencies are circumstance and person specific, and cannot be replicated everywhere or by everyone. At places within the scaled or converted presentations designers employ metaphors, surrogates, codes or signs for complex entities. For designers this becomes a second-nature’ to achieve the design objectives. Professionals working with converted presentations can read a temperature chart, a cardiogram read it like a ‘language’ Similarly a written musical score or a stenographer’s phonetic language does not recreate the original sound.

Musical chord


Graphical representations, often create an artistic, proportionate, or an aesthetic composition on their own. In a very complex situation a designer may deal with a graphical and / or scaled formation, of not original, but one that represents another graphical and / or scaled entity.

Electrical symbols on drawings

Designers, who deal with a variety of representations, be it, a scaled, graphical or metaphoric, are often not aware which form they are dealing with. They are oblivious of the transitions. It becomes a second nature for them. It is only when the desired objectives are not achieved, or when some unusual phenomena are discovered, that a designer begins to re-search the process.


This article in continuation of MEASURING UP >>



Post 394 – by Gautam Shah 


We define objects and happenings primarily with measures. Measures when combined with time show the changes that occur in things. Measures are very important in recording and recreating events and happenings, through their start, duration, termination, and the rate at which these actualize.

Roman Weight of stone

Measures define things in terms of lengths, areas, volumes or weights. Measures offer comparative scaling for sensorial perceptions, define load and work capacities, and determine reach and occupancy in space.

Human body limb sizes, reach and capacities -Basis of early measure systems

There was a time, when things were measured in terms of body sizes and capacities. Long distances were measured for the travel time required, like in lunch breaks or night halts. Short distances were measured in arm lengths, cubit (the length from the elbow to the tip of the middle finger), or foot steps of the traveller. Still smaller sizes were measured with the palm, breadth of a hand, length of a finger, or width of a thumb. Finer widths were measured in terms barley grains. Volumetric measures were the holding capacity of a limb like pinch or palm. Weights were measured in grains, fruits or stone pebbles, or in terms of carrying or displacement capacity of a person or animal, such as head load, a cart load, horsepower.

A common unit of weight in Ethiopia was the load – a simple measure of the amount carried by a beast of burden such as a camel

Measures are comparative facts. A thing to be measured is compared (equated) with something similar, familiar, or with a thing that has already been calibrated. Measures based on body sizes or capacities had many individual, racial and regional variations. Other standards were changeable and perishable. These units of measures were not replicable (recreate-able) and comparable. There was no hierarchical relationship between large and small measures. The conversion from one unit size to another was, often very illogical.

During the Middle Ages, major cities had their own set of measures and the public availability of these standards allowed visiting merchants to comply with local regulations. The official Viennese ell length standards for verifying the measure of different types of cloth sold are embedded in the cathedral wall, to the left of the main entrance. The linen ell, also called Viennese yard, (89.6 centimeters (35.3 in)) and the drapery ell (77.6 centimeters (30.6 in)) length standards consist of two iron bars.

The differences were somehow equated in barter trading between neighbours. But the same process was proving to be very difficult for trade with far of regions and transacted in some form of monetary units. There was an acute need for some common measure system. Gradually each trading block concurred to a common tradition of nominal measurements. Many different localized or regional measure systems flourished. Conversion between adjunct systems was not very difficult, as the trade occurred comparatively in small lots. Conversion of measures with adjoining trade regions was managed by intermediaries like brokers, caravan masters and shippers. The inconsistencies of the measure conversions were partly solved with monetary pricing replacing the bartered trading. The monetary trade system came to replace the barter trading, where only ‘universally’ measured goods were evaluated in a primary standard like gold.

Caravan Traders exchanging goods

At places things were transformed to different measure systems. Like grains were measured by volume (bushel) than by weight. Textiles were traded by weight than by lengths. Liquids (oils) were sold by volume. Yet, measure systems were mutually incompatible. To compound the problem each system had a different scale of sub fractioning. The complexity multiplied when differently fractionated measure units were equated with equally varied units and sub fractions of monetary units.

Measurement of mass – the gravitational force on the measure and is balanced against the gravitational force on the weights.

This problem of differential fractioning of measures and money was sought to be solved during the French Revolution. During the French Revolution (1870), the National Assembly of France asked French Academy of Sciences to formulate a scientific and rational measure system. Such a system was expected to be:

1 neutral and universal,

2 replicable anytime and anywhere,

3 to have decimal multiples,

4 to follow common prefixes,

5 be practical and simple to use.



Post 189 ⇒   by Gautam Shah 

Dimensional coordination

Ancient measure systems were based on the human limb sizes and body’s capacities. These were function-related measures such as: foot size and walking, thumb and width, fingers and numbers, palm and holding capacity, head load or horse power and carrying capacity, etc.

In a series of measure units, the sub units, though body related, were nearly independent. The interrelationships between sub units were simple but enforced. Various measures’ series were mutually incomparable and to an extent incompatible.

Across the world there were innumerable measure systems, but the Foot-Pound system became dominant due to extensive colonization by the British Empire.

The Metric System (created in France post Revolution period) was an abstract system with a Mathematical Order. It had the advantage of Logical Fractions. All measure units were divisible to 10X. But (early) Metric system had several sub units, many of which had no effective use. For some people the rationale of Metric system was too contrived as its scale did not relate to human body and its parts-whole-parts relationship.

In thePost Industrial Revolution‘ period, trade and industry all over the world recognized the need for a Universal Dimensioning Discipline. At that time better coordination was also required for conversion and transmission from old measurement systems to the new SI system of measurements. First worldwide understanding emerged in the adoption of SI as the Universal Measure System.


40 – Modulation with Body based Measure systems


41 – Foot-Pound (British) and Metric systems of measurements


42 – Need for a Coordinated Measure system


43 – Universal Dimensioning Discipline


44 – SI system of Measures


45 – ISO Modular Preferences -1


46 – ISO modular preferences -2


47 – Application of ISO Modular preferences


48 – Implications of ISO Modular coordination of Dimensions


49 – Implications of ISO Modular coordination of Dimensions -2


50 – Implications of ISO Modular Coordination of Dimensions -3

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Post 175 ⇒   by Gautam Shah 



Here in few slides How measures are modulated is shown.  Measures are modulated with human limb sizes, for coordination with other measures, such as Length, Height, Width and Up-down, Left-right, Far-near, etc. Measures that are beyond sensorial capacities of perception are reduced or converted to other scales. Measures in pure numbers have a mathematical order which persists through reduction, enlargements, etc. Measures are also divided-added up to form a series.



25 Measures and dimensional referencing


26 Sensing objects beyond their size measures


27 Sensory affectations


28 Surrogate – Metaphoric – Symbolic representations


29 Graphical presentations


30 Dealing with scaled and graphical representations


31 System of Modulation and proportions -1


32 System of Modulation and proportions -2


33 System of Modulation and proportions -3


34 System of Modulation and proportions – 4


35 Numeric orders – Pure numbers


36 Modulation with Human limb sizes


37 ISO Modulation for Papers