Area Comparison

[Please note first]

This app shows no maps and no land prices. It cannot work out an area

for you either, since a phone has no sensor for that. You enter an area

you already know, and it is set against sizes that are already fixed.

Names shown are the trademarks of their respective owners; this app is

not affiliated with any of them.

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🟩 Area Comparison — how big is that, really?

"510,000 square metres" tells you almost nothing on its own. That is

Tokyo Disneyland, and it comes to 10.9 Tokyo Domes.

Enter one area and compare it against 27 things, from a sheet of A4

paper to the surface of the Earth.

■ Two ways to use it

▪ About this big — the five things closest to your area, smallest first

▪ How many? — how many of each of the 27 things your area comes to

"About this big" shows the nearest five; the full list of 27 sits just

below it. The same entries serve both tabs.

■ Twenty-seven things

A4 paper (0.671 sq ft, or 0.06237 m²), a tatami mat, one tsubo, a table

tennis table, a six-mat room, a parking space, badminton, volleyball, tennis and

basketball courts, a 50 m pool, an American football field, a football

pitch, the Tokyo Dome, Tokyo Disneyland, the Imperial Palace, inside

the Yamanote Line, the 23 wards of Tokyo, Lake Biwa, Singapore,

Kagawa, Tokyo, Hokkaido, Japan, Russia, and both the land and the

whole surface of the Earth (510,100,000 km²).

Tap any row to load its area.

■ The Tokyo Dome, a Japanese unit of area

In Japan, large areas are quoted in Tokyo Domes much as football fields

are used elsewhere. The figure counted is 46,755 m², the building

footprint with the roof on; the playing field alone is about 13,000 m²,

a factor of 3.6 smaller.

■ One tsubo is exactly two tatami mats

One ken is 6 shaku, or 20/11 m, and a square of that side is one tsubo:

400/121 m². A tatami mat is 6 by 3 shaku, or 200/121 m² — exactly half.

Enter 400 m² and the tsubo row reads exactly 121.

■ Exact figures and ranges are kept apart

Courts and pools are exact, their size fixed by the rules of the sport:

a doubles tennis court is 23.77 by 10.97 m, or 260.7569 m².

Parking spaces and football pitches vary, so a range is shown as well as

a typical figure. The Laws of the Game allow 90 to 120 m by 45 to 90 m.

105 by 68 m, or 7,140 m², is recommended for international matches, and

the range in the list, 6,400 to 8,250 m², is what those matches allow:

100 to 110 m by 64 to 75 m. Ranges are for reading only; comparisons

use the typical figure.

■ Readable at every scale

The same screen shows "0.671 sq ft" and "510,100,000 km²".

Each row gives the thing's area in its own unit.

sq ft → m² → km²

■ Good for

▪ Making sense of a figure in square kilometres from the news

▪ Putting the size of a room into everyday terms

▪ Any moment you see a number and wonder whether it is big

■ Things worth knowing (included in the app)

▪ The Tokyo Dome of "so many Tokyo Domes" is the building footprint,

46,755 m², not the playing field

▪ One tsubo is exactly two tatami mats, and rounding the mat to whole

centimetres breaks that

▪ Area grows with the square of length: double every side, four times

the area

▪ One are is 100 m², one hectare 10,000 m², one square kilometre

1,000,000 m²

▪ A football pitch has no fixed size; 105 by 68 m is a recommendation

▪ National areas shift a little every year; Singapore keeps growing

■ How the app is built

▪ A single screen and no settings page

▪ Your last five entries are kept and can be tapped to restore

▪ One tap copies the result

▪ Japanese and English, following your device language

▪ No account needed. The comparison runs on your device and your figures are never sent anywhere

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Note: land areas are published figures (Geospatial Information Authority

of Japan and others, 2020s) and shift a little from year to year with

reclamation and resurveying. This app shows no maps and no land prices,

and cannot work out an area.