How to turn a square plot of land into a rectangle

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

28 September 2025

After reading my response to his question about commercial parking space business, John Mutua sent in a follow-up question: not about the business, but about the size of land. He says, “…this plot was sold to me as a quarter acre [and] my understanding is that it should be 100ft by 100ft. Was I cheated?”

I have discussed this matter before – in 2017 – and explained that what Kenyans call an eighth of an acre is actually not an eighth of acre! In fact, most of the time, even the famous 50-by-100 plot is not 50ft by 100ft.

As I have stated several times in the past, the imperial system of units is cumbersome and user unfriendly. I can never understand why anyone would prefer it to the metric system. One acre, for example, is equal to 43,560 square feet. (Why not 40,000?) Hence an eighth of an acre is simply this number divided by eight; which is 5,445sq.ft.

Now, a plot of land measuring 50ft by 100ft comes to exactly 5,000sq.ft. It is therefore about 8 per cent smaller than an eighth of an acre. But that’s not the end of it: many a time, surveyors convert the 50ft to metres to get 15.24m. They round this off to 15m and then survey the plot as 15m by 30m.

Now if we work backwards, we find that 15m is actually equal to 49.2ft and 30m = 98.4ft; so, the area of the plot comes to 4,841sq.ft. This is over eleven per cent smaller than an eighth of an acre…

In Mutua’s case, the surveyor wanted to get a rectangular plot whose length is double its width – a shape similar to the 50x100 – but with an area of 10,000sqft (100ft x 100ft). The calculation is done in two steps: first, find a half of the area – 10,000/2 = 5,000; secondly, find the square root of the result – the answer is 70.7ft and this is the width of the plot. The length is simply double this number and it comes to 141.4ft.

Before proceeding, it is important to note that 70.7ft is NOT equal to 70 feet and 7 inches! It is 70 feet and 8.5 inches. While the length is 141ft and 5 inches. Cumbersome, isn’t it?

So, is Mutua’s plot a quarter acre? The answer is yes and no. Yes, because Mutua believes a quarter acre is 10,000sq.ft. and no because a real quarter acre is 10,890 which would work out to 73.8ft by 147.6ft.