A software engineer

Why metric is better

Martin Vlietstra

Computer programs enable people to collect, manipulate and store data. Data can be in many forms – text, numbers, pictures, music and so on. The most common form of numeric data is money. It is no accident therefore that decimalisation occurred as the computer revolution was gathering pace.

I wrote my first computer program as a student in 1969 and the British currency was decimalised in 1971 – 14 years after India, 10 years after South Africa, 5 years after Australia. Britain was in fact the last major country to decimalise her currency. I shudder to think of the extra programming work (not to mention bugs) that occurred during the last years of pounds, shillings and pence.

I recently wrote a computer system to record the progress in children’s development. Fortunately it is a legal requirement that all medical records in Britain now use metric units, otherwise consider the problems that I would have had. Traditionally the weight of a baby was given in pounds and ounces and its length in inches. The weight of an adult (or a teenager) was traditionally given in stones and pounds and the person’s height in feet and inches. When exactly should the program start using stones and pounds rather than just pounds or pounds and ounces?

Likewise, when should the program start using feet and inches rather than just inches? If a graph of the child’s development was being plotted, what should the axes be in – inches, feet and inches or decimals of a foot? Likewise, should weight be shown in pounds, in stones and pounds or in stones and decimals of a stone? All basic computer systems have the ability to handle numbers in decimal format but writing special pieces of code to display feet and inches or stones and pounds is expensive. The metric system combines the simplicity of a decimal system and in addition gives an easy transition from “smaller” to “larger” units. A baby’s birth weight would typically be recorded as 3500 g, but this easily converts to 3.5 kg. Similarly, a birth length of 60 cm easily converts into a height of 0.6 m. These simple conversions are not possible with the imperial system.

Martin has degrees from the Universities of Manchester and Natal, is a Chartered Information Technology Engineer and a European Engineer.