Stair Riser & Tread Calculator
Comfortable riser/tread ratio checker.
Enter your values
Enter the riser height in in.
Enter the tread depth in in.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 2R + T value
- 25 in
- Comfort check
- Comfortable
- Riser + tread sum
- 18 in (target 17-18 in)
- Angle
- 32.5°
Quick answer
A comfortable stair keeps 2 x riser + tread between about 24 and 25 inches.
comfort = 2 x riser + tread
At a glance
| What it does | Comfortable riser/tread ratio checker. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Riser height, Tread depth |
| Main output | 2R + T value |
| Formula | comfort = 2 x riser + tread |
| Cost | Free — no sign-up, no download |
How to use the Stair Riser & Tread Calculator
- 1Enter your planned riser height.
- 2Enter your planned tread depth.
- 3Check the 2R+T comfort formula falls between 24 and 25 inches.
Inputs explained
- Riser height(in)
- Enter the riser height in in.
- Tread depth(in)
- Enter the tread depth in in.
Worked example
Using the values the calculator loads with:
Inputs
- Riser height7 in
- Tread depth11 in
Results
- 2R + T value25 in
- Comfort checkComfortable
- Riser + tread sum18 in (target 17-18 in)
- Angle32.5°
Frequently asked questions
Where does 24-25 come from?
It approximates a typical human stride and is used across most residential stair design guides.
What if my stairs fail the check?
Adjust riser height or tread depth slightly, or add a landing to change total rise.
What do I need to enter into the Stair Riser & Tread Calculator?
Just 2 values: riser height, tread depth. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Stair Riser & Tread Calculator work out the answer?
A comfortable stair keeps 2 x riser + tread between about 24 and 25 inches. It applies the formula comfort = 2 x riser + tread and shows the working so you can check each step by hand.
Is the Stair Riser & Tread Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.