Japanese Ramp Gradients: Slope, Landings & Width

The requirement

A general ramp in Japan can be no steeper than 1/8 (12.5%). The figure sits in the Building Standard Law Enforcement Order, Art. 26 §1, item 1. It covers any ramp built in place of stairs. It applies to every building, with no size or use carve-out. So it binds an ordinary house too.

The surface has its own rule. It must be rough-finished or a non-slip material (Art. 26 §1, item 2). The Order names no numeric slip-resistance coefficient. It is a quality test, not an mm value.

BSL Enforcement Order Art. 26

Landing, width and handrail come from the stair rules. Art. 26 §2 applies the stair articles to a ramp as well. Only the riser and tread parts drop out. A ramp has neither.

Landing: needed only where a straight run climbs more than 4 m. Same trigger as a house stair. Where one is needed, it must be at least 1.2 m (1,200 mm) deep.
Width: at least 750 mm, the same table row that sets a house stair’s width.
Handrail: every ramp needs one, same as a stair. But no numeric height is fixed in the primary text.

This 1/8 is not the accessible-ramp figure. Japan runs a second, stricter standard for accessible design. It sits in the order under the barrier-free law (バリアフリー新法施行令, formally 高齢者、障害者等の移動等の円滑化の促進に関する法律施行令, Cabinet Order No. 379/2006). On an accessible route, the slope must be no steeper than 1/12. It can relax to 1/8 where the rise is 160 mm or less (Art. 18 §2 item 4). The same figure applies to site paths under item 7. Art. 13 sets a milder bar too. A ramp at 1/12 or gentler, with a rise under 160 mm, needs no handrail. Nor does one at 1/20, at any rise.

That stricter regime does not reach an ordinary house. Its Art. 4 lists the buildings its rules bind, called 特定建築物. The list runs to schools, hospitals, theatres, department stores, hotels, offices and the like. A private detached house is not on it. So for a self-build, the 1/12 figure (1/8 on short rises) is a smart guide, not a legal duty.

One honest caveat on that scope point. It rests on a secondary source, not a direct read of the Art. 4 text this pass. Trust it a shade less than the 1/12 figure itself. That one comes straight off MLIT’s own published checklist.

Work it out on site

Say you are building a general ramp up a change of level of 300 mm. It is a plain ramp, not an accessible route under the barrier-free law. How long does it need to be?

Apply the 1/8 limit. At 1/8, the run is 8 × the rise. 300 mm × 8 = 2400 mm (2.4 m) of run.
Check the landing trigger. A 300 mm rise is well under the 4 m trigger. No mid-ramp landing is required. Just level ground at the top and bottom.
Check the width. Keep the ramp at least 750 mm clear.

So: about 2.4 m of run at 1/8, and 750 mm wide. The slope calculator does the rise-over-run maths for you.

Do it in 5 seconds

Part of the Japanese building-rules hub — the hub, with the Enforcement Order articles that set the rules.
Building the stairs that ramp might replace? See Japanese stair rules.

Sources

Building Standard Law Enforcement Order (建築基準法施行令), Art. 26 (general ramp gradient and surface, and its cross-reference to Art. 23–25 for width, landing and handrail). Read the current consolidated text at laws.e-gov.go.jp.
高齢者、障害者等の移動等の円滑化の促進に関する法律施行令 (barrier-free law enforcement order, Cabinet Order No. 379/2006), Art. 18 §2 item 4 (accessible-route ramp gradient/width/landing), Art. 13 (general-standard ramp handrail-exemption threshold), Art. 4 (特定建築物 scope list). Value and article confirmed against MLIT’s own official checklist PDF: mlit.go.jp. The Art. 4 scope conclusion — that an ordinary house isn’t on that list — is corroborated via secondary source only; confirm it directly against e-Gov before relying on it for anything beyond an ordinary self-build.

Read this first. Japan’s Building Standard Law and Enforcement Order are a single, continuously-amended text, checked here as of 29 July 2026 at the official e-Gov law database. The 1/8 figure above is the general BSL ramp rule, which does bind an ordinary house. The 1/12 (relaxed to 1/8) figure is Japan’s separate, gentler accessible-design ramp standard under the barrier-free law — a real, MLIT-confirmed figure, but one that by scope doesn’t legally bind an ordinary detached house; the scope conclusion itself rests on a secondary source this pass, not a primary Art. 4 text read end to end. Always confirm the current text at laws.e-gov.go.jp or mlit.go.jp before you build to these figures.

Frequently asked questions

What is the maximum ramp gradient in Japan?

No steeper than 1/8 (12.5%), for a general ramp used in place of stairs. That is Art. 26 §1, item 1 of the Building Standard Law Enforcement Order. It applies to every building, with no size or use carve-out. So it binds an ordinary single dwelling house too.

Does the ramp need a non-slip surface?

Yes. Art. 26 §1, item 2 says the surface must be rough-finished or a non-slip material. The rule names no numeric slip-resistance coefficient. It is a quality test, not a number you can measure to.

What landing and width figures apply?

Art. 26 §2 applies the stair rules to a ramp, minus the riser and tread parts (a ramp has none). So a landing is needed only where a straight run climbs more than 4 m, at least 1.2 m deep where required. Width: at least 750 mm, from the general stair table.

Is there a handrail requirement?

Yes. Every ramp needs a handrail, same as a stair, via the cross-reference to the stair handrail rule (Art. 25 §1). But no numeric height is fixed, same as for a stair.

Is this the same figure as Japan's accessible-ramp standard?

No. The 1/8 figure is the general Building Standard Law rule for any ramp replacing stairs. Japan's barrier-free law order (バリアフリー新法施行令, Cabinet Order No. 379/2006) is stricter: 1/12 on an accessible route, or 1/8 where the rise is 160 mm or less (Art. 18 §2 item 4). It binds listed buildings only, like schools, hospitals, hotels and shops. Not an ordinary house.