Stair Calculator

How to use Stair Calculator

1. Open Stair Calculator in your browser — it loads instantly and works offline once cached.
2. Enter your values in the input fields. Every field is labelled so you know exactly what to type.
3. The result updates automatically as you type — there is no "submit" round-trip to a server.
4. Adjust any input to compare scenarios and see how the outcome changes in real time.
5. Copy or note the result. Nothing you enter is stored or sent anywhere.

Why use Stair Calculator?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full construction suite, so related stair tasks are one click away.

What people use Stair Calculator for

• Working out rise and run for a deck, a loft conversion or a basement staircase.
• Checking an existing staircase against current building regulations before a survey.
• Calculating the number of risers needed for a given floor-to-floor height.
• Estimating stringer length and total run before ordering timber.

Stair Calculator: limits and things worth knowing

• Total rise is measured floor surface to floor surface, not floor to ceiling — the most common source of a wrong answer.
• Every riser in a flight must be within a few millimetres of every other. An uneven riser, especially the first or last, is the classic trip hazard and a routine inspection failure.
• Typical domestic limits are a maximum rise around 190-200 mm and a minimum going around 220-250 mm, but the exact figures are set by your local building code and differ between the UK, US and EU. Check the applicable code before cutting.
• The rule of thumb that rise times going should fall near 45,000 mm² (or 2 × rise + going ≈ 630 mm) produces comfortable stairs and is worth checking your result against.
• This calculator is a design aid, not a compliance certificate. Have the final design checked against the regulations that apply where the work is being done.

Is it private and secure?

Your privacy is built in. Stair Calculator runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Why Browser-Based Tools Are Safer for Your Files — Most online converters upload your files to a server. Client-side tools don't. Here's why that difference matters for privacy.