How to Work Out How Much Flooring to Order

Works out how many cases of flooring a room needs. Flooring is usually sold by the case, each covering about one tsubo. The size in tatami mats and in tsubo is shown as well, to give a sense of the room.

Flooring is usually sold by the case, each covering about one tsubo. This works out how many cases a room needs.

cases=area×(1+allowance)area per case\text{cases} = \left\lceil \dfrac{\text{area} \times (1 + \text{allowance})}{\text{area per case}} \right\rceil

Part cases cannot be bought, so the figure is rounded up.

Tatami and tsubo

The area is also given in tatami mats and in tsubo. A mat is taken as 1.62 m², the lower limit used in property advertising, and a tsubo is exactly 400÷121=3.3058400 \div 121 = 3.3058 m². Two mats make one tsubo.

Example

A room of 3.6 by 2.7 m is 9.72 m², six mats, or 2.94 tsubo. Allowing 10% brings it to 10.69 m², and at 3.3 m² a case that is 10.69÷3.3=3.2410.69 \div 3.3 = 3.24, rounded up to 4 cases. Without the allowance three would do, so that single extra case is a noticeable step.

Judging the allowance

Rooms with many cut-outs, boards laid diagonally, or a pattern that has to line up all waste more. A plain rectangular room laid parallel needs 5 to 10%; a complicated one nearer 15%.

Notes

The area per case varies by product. Around 3.3 m², one tsubo, is common, but half-tsubo cases of 1.65 m² exist. Check what the product actually states.