(1) ​The ratio of the horizontally projected area of a building to its land area (Building Area/Land Area) is called the building-to-land ratio, and its limit is set by city planning.

(2) If the land spans more than one area, the calculation is based on a weighted average according to the area ratio.
<Calculation Example>
In the case of a 100㎡ site with the building coverage ratios: 6/10 for 30㎡ and 4/10 for 70㎡
(30 X 6/10 + 70 X 4/10) X 1/100 = 0.46 → 46%

(3) Buildings that fall under any of the following categories are eligible to receive an increase in the building-to-land ratio.

• Properties that meet the conditions specified by the specified administrative agency, such as a property located at the corner of a city block
• Fire-resistant buildings in areas with a building-to-land ratio limit of less than 8/10 and in fire prevention zones

(1) The ratio of the total floor area of a building to its land area (total floor area divided by land area) is called the "floor-area ratio," and its limit is set by city planning and other regulations.

(2) ​If the width of the road facing the property is less than 12 meters, the floor-area ratio will be limited to the smaller of the value obtained by multiplying the road width (m) by 4/10 or 6/10 and the value in (1) above.

(3) If the site extends over more than one area, the calculation is based on a weighted average according to the area ratio. (The calculation is the same as in 2(2).

(4) ​If there is a wide road (specified road) with a width of 15m or more within a distance of 70m from the site, and the width of the road facing the property is 6m or more (less than 12m), the floor area ratio (calculated according to the width of the road facing the property) can be increased.

(1) In principle, a building cannot be built unless the property is facing a road classified as such in accordance with the Building Standards Act (hereinafter referred to as the Act) for at least 2 meters in length.

• Visit a local office of the specified administrative agency for more information on roads classified as such in accordance with the Act .
•  Note that some of the public roads are NOT classified as roads as per the criteria of the Act.

(2) As a general rule, roads 4 meters or less in width are not roads as per the Act. However, in case Chapter 3 of the Act applies, the following are recognized as roads in accordance with the Act: roads that are lined with buildings  and are designated by the specified administrative agency (so-called Section 2 Roads).
*As of November 23rd, 1950, when the Act was enacted, or at the time of incorporation into a city planning area or quasi-city planning area.

Types of roads (at least 4 meters in width)

• 1st Roads (Article 42 Clause 1 of the Act): Roads as per the Act
• 2st Roads (Article 42 Clause 1 of the Act): Roads as per the City Planning Law and the Urban Land Readjustment Law
• 3st Roads (Article 42 Clause 1 of the Act): Roads existing at the time when the provisions of Chapter 3 of the Act came into effect
• 4th Roads (Article 42 Clause 1 of the Act): Roads with a project plan under the Road Act, City Planning Act, etc., which has been designated by the specified administrative agency as the plan scheduled to be executed within two years.
• 5th Roads (Article 42 Clause 1 of the Act): Roads built for the purpose of using the land as a site for buildings without complying with the Road Act, City Planning Act, etc., which have been designated as such by the specified administrative agency.
• Section 2 Roads (Article 42 Clause 1 of the Act): Refer to (2) above.