40 × 80 or 50 × 100? Kenyan Plot Sizes, Explained Properly
7 min read · Updated 11 Oct 2026
Two people can stand on the same plot and mean completely different things by "an eighth". It is worth five minutes to get this right, because plot size is the second thing you decide after location, and it is the one people most often get wrong.
The numbers, plainly
| What people say | Square feet | Acres | Square metres |
|---|---|---|---|
| 40 × 60 | 2,400 | 0.055 | 223 |
| 40 × 80 | 3,200 | 0.073 | 297 |
| 40 × 90 | 3,600 | 0.083 | 334 |
| 50 × 90 | 4,500 | 0.103 | 418 |
| 50 × 100 ("an eighth") | 5,000 | 0.115 | 465 |
| A true eighth acre | 5,445 | 0.125 | 506 |
| 100 × 100 ("a quarter") | 10,000 | 0.230 | 929 |
| A true quarter acre | 10,890 | 0.250 | 1,012 |
| One acre | 43,560 | 1.000 | 4,047 |
Two things jump out.
First: a 50 × 100 is not quite an eighth. It is 5,000 square feet against a true eighth of 5,445, about 92%. Nobody is cheating you; the names stuck decades ago and everyone uses them loosely. But if you are comparing a "50 × 100 at 1.7M" with "an eighth at 1.8M", you are not comparing the same thing.
Second: the jump from 40 × 80 to 50 × 100 is bigger than it sounds. It is 56% more ground. That is the difference between a house with a compound and a house that fills its plot.
What actually fits
Before the floor plan, subtract the setbacks. County by-laws require you to leave space between your building and the boundary, commonly around three metres, though it varies by county and by zone. Confirm with the county before you design, not after.
40 × 60: 2,400 sq ft
Tight for a family home. This size makes more sense commercially: a shop block on a busy stretch, where you build to the frontage and the ground floor earns its keep. We have two of these at Mastore.
40 × 80: 3,200 sq ft
The workhorse. A three-bedroom bungalow of 1,200–1,500 sq ft fits comfortably, with parking and a modest compound. Add a DSQ and it gets snug but it is done all the time. This is the most common plot size sold along Thika Road, and the most liquid when you come to resell.
50 × 100: 5,000 sq ft
Room to breathe. A bungalow with a DSQ, parking for two, a drying yard and an actual garden. Or a two-storey maisonette with ground to spare. If you plan to be in the house twenty years, the extra ground is what you will be grateful for.
100 × 100: 10,000 sq ft
A quarter, give or take. This is mansionette ground, or a small rental block if the zoning allows it. Our five-bedroom in Ngoigwa sits on exactly this.
How to compare two plots honestly
Divide the price by the square feet. It takes ten seconds and it ends most arguments.
- A 40 × 90 at KSh 1.2M → 3,600 sq ft → KSh 333 per sq ft
- A 50 × 100 at KSh 1.7M → 5,000 sq ft → KSh 340 per sq ft
- A 50 × 90 at KSh 900,000 → 4,500 sq ft → KSh 200 per sq ft
Now the differences are visible. But do not stop at the number. A plot on the tarmac is worth more per foot than one four hundred metres back, and it should be. The rate tells you what you are paying. Your eyes tell you whether it is worth it.
Three mistakes worth avoiding
Buying the smallest plot you can afford in an area you cannot afford. A 40 × 60 in an expensive area is usually worse value than a 50 × 100 in the next area along. Land appreciates with the neighbourhood, not with the plot number.
Ignoring the shape. Two plots can both be "50 × 100" and one is a neat rectangle while the other is a long thin strip after a road took a corner. Ask for the registry index map.
Forgetting the access road. A bigger plot with no proper access is worth less than a smaller one you can drive to in the rain. Go and look in the rain if you can.
A rule of thumb
If you are buying to build a home, take the biggest plot you can afford in the area you actually want to live in. If you are buying to hold and resell, 40 × 80 and 50 × 100 are the sizes that sell fastest, because that is what the next buyer will be looking for.
Common questions
Is 50 by 100 an eighth of an acre?
What is 40 by 80 in square feet?
Can I build a three bedroom house on a 40 by 80?
How many square feet is an acre?
Kareithi will answer straight. He will also tell you when a plot is not right for you.