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2026-09-09
Zoning districts, building coverage ratio and floor area ratio ― how big a house can be built on that land
Two plots of the same 100 square metres can allow houses of very different sizes depending on where they are. The 13 zoning districts (用途地域) decide "what may be built", and the building coverage ratio (建ぺい率) and floor area ratio (容積率) decide "how much may be built". This article explains the mechanism with a worked example, the corner-lot relaxation, height limits and how to look things up, from the practical viewpoint of a licensed real estate agent.
About this translation ― This page is an English translation of an article originally written in Japanese by KuraLab's operator, a licensed real-estate transaction specialist (宅地建物取引士) and administrative scrivener (行政書士) in Japan. The Japanese original is the authoritative text; where the two differ, the Japanese version prevails. The article explains Japanese law and procedure in general terms as of the date shown. It is not legal, tax or immigration advice for your situation ― please confirm with a licensed professional in Japan. Japanese terms are kept in parentheses so you can search for them. Read the Japanese original
"The city planning map says 200, so I can build up to 200 square metres of total floor area, right?" Those were the first words of a man who wanted to build a two-family house on 100 square metres of inherited land. Zoning district: Category I residential zone; building coverage ratio 60%; floor area ratio 200%. But the road in front was 4 metres wide. Under the front-road restriction for residential zones, 4 × 0.4 = 160%. The lower of the city plan's 200% and the road's 160% applies, so the ceiling is 160 square metres. The two-family plan the man had drawn was 195 square metres of total floor area. This article is about those 35 square metres.
Buying land, building on inherited land, hearing that a condominium is going up next door. In every case, the first things to check are the "zoning district" (用途地域) and the "building coverage ratio and floor area ratio" (建ぺい率・容積率). The zoning district is the classification that decides what may be built on the land; the two ratios are the numbers that decide how big it may be. Between them they set almost the whole ceiling on how the land can be used.
There are 13 zoning districts under the City Planning Act. Eight residential (Category I and II exclusively low-rise residential, rural residential, Category I and II exclusively medium-to-high-rise residential, Category I and II residential, quasi-residential), two commercial (neighbourhood commercial, commercial) and three industrial (quasi-industrial, industrial, exclusively industrial). As the names suggest, tall buildings and large shops cannot be built in exclusively low-rise residential zones, while almost anything can be built in a commercial zone. You can look up the zoning of your own land by lot number on the municipality's city planning map (most municipalities publish it online).
In broad terms: the low-rise residential group (Category I and II exclusively low-rise, rural residential) is mainly low-rise housing, with a height limit of 10 to 12 metres and only limited small shops. The medium-to-high-rise group (Category I and II exclusively medium-to-high-rise) allows condominiums, with limits on the scale of shops and offices. The general residential group (Category I and II residential, quasi-residential) allows shops, offices, hotels and the like in addition to housing, depending on scale. The commercial group (neighbourhood commercial, commercial) is for shops, offices and commercial facilities, with almost no restriction in the commercial zone. The industrial group (quasi-industrial, industrial, exclusively industrial) is centred on factories, and housing cannot be built in an exclusively industrial zone.
The building coverage ratio is "the ratio of the building area (the building seen from directly above) to the site area." On 100 square metres of land with a 60 per cent coverage ratio, the first floor can be at most 60 square metres. The remaining 40 square metres become garden, parking or the gap to the neighbour. It is a number meant to prevent the spread of fire and secure sunlight and ventilation, set by the city plan within a range of 30 to 80 per cent for each zoning district.
The floor area ratio is "the ratio of the total floor area (the sum of the floor area of every storey) to the site area." On 100 square metres with a 200 per cent floor area ratio, the total floor area can be at most 200 square metres. For two storeys that is 100 per storey; with a 60 per cent coverage ratio, it becomes 60 + 60 + 60 = 180 square metres over three storeys. The floor area ratio also has a "restriction by the width of the front road": where the road is less than 12 metres wide, the ceiling is the lower of the city plan's ratio and width (metres) × 0.4 in residential zones or × 0.6 elsewhere. For land in a residential zone facing a 4 metre road, the ceiling is 4 × 0.4 = 160 per cent. Even if the city planning map says "200", a narrow road means only 160 can be used. This is an easily overlooked point.
As a worked example for a 100 square metre site, coverage 60%, floor area ratio 200%, front road 4 metres in a residential zone: the building area ceiling at 60% coverage is 60 square metres for the first floor, leaving 40 of open space. The total floor area ceiling under the city plan is 200. The front road gives 4 metres × 0.4 = 160%, so the real ceiling is 160 square metres, and 40 cannot be used. The lower of the city plan's ratio and the ratio derived from the front road width is the ceiling.
There are relaxations. A corner lot (a site facing two roads) or a fire-resistant building in a fire prevention district gets 10 per cent added to the coverage ratio each. For the floor area ratio, there are rules that exclude part of the floor area of a basement or garage from the total. Conversely, height restrictions (absolute height, road slant-plane, adjacent-site slant-plane, north-side slant-plane, and sunlight-shadow regulation) can prevent you from using the full floor area ratio. Exclusively low-rise residential zones have an absolute height limit of 10 or 12 metres, which can make three storeys difficult.
The effect on land prices is direct. For the same area, the higher the floor area ratio, the more floor area can be built, so the price is higher. The district classifications on the roadside land value map mentioned in another article on this site (ordinary residential district, ordinary commercial and mixed residential district, and so on) broadly correspond to these zoning districts. If the zoning changes from exclusively residential to commercial, what can be built changes, and the land price changes by an order of magnitude.
The order of checks in practice is: zoning district, coverage and floor area ratios, width of the front road, height restrictions and sunlight-shadow regulation, and the designation as a fire prevention or quasi-fire prevention district. Pin down these five on the city planning map and at the municipal counter, then ask the designer "what kind of house can be built on this land," and the conversation goes quickly. All five are always written in the explanation of important matters for a second-hand house.
The numbers in order. Site 100 square metres, coverage 60%, so the first-floor building area is at most 60 square metres. The floor area ratio is 200% under the city plan and 160% from the 4 metre front road; the lower, 160%, applies, so the total floor area is at most 160 square metres. With three storeys, 60 + 60 + 40 = 160. But a Category I residential zone has sunlight-shadow regulation, in this city "4 hours within a 5 metre range, 2.5 hours at 10 metres." The designer's shadow diagram showed that part of the north side of the third storey had to be lowered, and what could actually be built was 58 on the first floor, 58 on the second and 38 on the third, 154 square metres. Down 41 square metres from the original 195, so one room was removed from the parents' side of the two-family house.
Some was recovered through relaxations. Not a corner lot, so no 10% addition to the coverage ratio. But by building the garage into the first floor and using the rule that excludes the garage floor area (up to one fifth of the total) from the floor area ratio calculation, 14 square metres of garage were excluded. The ceiling on total floor area became 160 plus the excluded garage, effectively 174 square metres. Since the shadow regulation limited the third storey, this was used as an overhang on the second floor, and the final total floor area including the garage was 168 square metres. Not the original 195, but 14 square metres back from 154.
One example the other way. In another consultation, the same 100 square metres of land faced a 6 metre road. 6 × 0.4 = 240%, so the city plan's 200% could be used in full, 200 square metres of total floor area. A difference of 2 metres in road width is a difference of 40 square metres of buildable floor. The gap I described above, "even if the map says 200, a narrow road allows only 160," is these 40 square metres. Land prices build in this difference: land facing a 6 metre road was traded at about 10% more per square metre in the same neighbourhood.
After getting an area from the Land Price Scan tool (土地価格スキャン), if you want to know "how much can be built on that area," multiply the area by the coverage and floor area ratios. If the land you traced is 100 square metres with coverage 60 and floor area ratio 200, the ceilings are 60 square metres on the first floor and 200 in total, and the order of magnitude appears at once.
The answer to "it says 200" was 160 because of the road width, 154 because of the shadow regulation, and 168 with the garage exclusion. The 195 square metres on the drawing was a number that could never have been built. Of the five things I said to pin down first, zoning, the two ratios, front road width, height and shadow regulation, and fire prevention district, the third and fourth were decisive for this land. The number on the city planning map is the ceiling of ceilings; the real ceiling is decided by the road and the shadows.
Written by: 長澤 湊（licensed real-estate transaction specialist, administrative scrivener, assistant surveyor） Content checked on: 2026-10-14
This article is a general explanation of Japanese rules and procedures, not advice on an individual case. Figures and rules are as of the date shown. For your own situation, consult a lawyer, judicial scrivener, tax accountant or administrative scrivener in Japan.