Square Metres to Tsubo: Converting an Area into Tsubo

Converts square metres to tsubo. One square metre is 121/400 = 0.3025 tsubo.

Explanation

Japanese property is measured in square metres on paper and discussed in tsubo in practice. A tsubo is a traditional unit of area, a square of about 1.82 m on a side, historically the floor space of two tatami mats. It is still how buyers, agents and builders think about size, so a metric area usually has to be translated.

1\ \text{m}^2 = \dfrac{121}{400}\ \text{tsubo} = 0.3025\ \text{tsubo}

With an area $S$ in square metres and $T$ tsubo:

T = S \times 0.3025

This is the friendly direction. Going from tsubo to square metres means multiplying by 400/121, which never comes out even; coming back, 121/400 is exactly 0.3025.

Example

Take the default, 100 m².

T = 100 \times \dfrac{121}{400} = \dfrac{12100}{400} = 30.25

So 100 m² is 30.25 tsubo. Multiplying by 0.3 gives a quick estimate that lands slightly low: 100 × 0.3 = 30.

Where you use it

Working out a price per tsubo, the figure everyone compares. It is the total price divided by the number of tsubo, so a metric area has to be converted first.
Converting unit prices: multiply a price per square metre by 3.3058 to get the price per tsubo, and by 0.3025 to come back.
Check which area you were handed. A Japanese condominium has two official floor areas: the registered one, measured inside the walls, and the larger advertised one, measured to the centre of the walls. Convert the one that matters for your purpose.