Calculate stair dimensions per IRC building code. Get riser height, tread depth, stringer length, and angle. Sorted by comfort score for optimal stairs.
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IRC building code allows max 7.75 inch risers. Ideal riser height is 7-7.5 inches. The comfort rule is 2R + T = 24-25 inches.
Minimum tread depth is 10 inches per IRC code. Ideal is 10-11 inches. Outdoor stairs can go up to 14 inches for a more gradual climb.
Stringer length = √(total rise² + total run²). For a 9-ft rise with 12-ft run: √(81 + 144) = 15 feet. Add 12 inches for cutting waste.
The Stair Calculator is a free online tool that lets you calculate stair dimensions per building code with riser height, tread depth, and stringer length. It is part of NexTool's collection of free tools designed to help you work faster and more efficiently.
Using the Stair Calculator is simple: visit the tool page, enter your data or input into the provided fields, and get instant results. No downloads, installations, or sign-ups are required. The tool runs directly in your web browser for maximum convenience.
Yes, the Stair Calculator is 100% free to use with no limitations. There is no registration required, no daily usage caps, and no hidden fees. You can use it as many times as you need.
The Stair Calculator uses industry-standard formulas and algorithms to deliver reliable results. While the tool is designed for accuracy, results should be used as estimates and guidance. For critical decisions, always consult a qualified professional.
Yes, the Stair Calculator is fully responsive and works perfectly on smartphones, tablets, and desktop computers. Simply open NexTool in your mobile browser and navigate to the tool — no app download required.
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Calculate stair dimensions per IRC building code. Get riser height, tread depth, stringer length, and angle. Sorted by comfort score for optimal stairs.
NexTool's Stair Calculator is completely free to use with no sign-up required. Your data is processed directly in your browser and never sent to our servers, ensuring complete privacy and instant results.
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| Steps | Riser | Tread | Total Run | Angle | Comfort | Code |
|---|---|---|---|---|---|---|
| 21Best | 5 1/8" | 14" | 23.3' | 21.1° | 96 | Issues |
| 20 | 5 3/8" | 14" | 22.2' | 22.1° | 94 | Issues |
| 15 | 7 1/4" | 10 5/8" | 12.4' | 36.0° | 90 | Pass |
| 16 | 6 3/4" | 11 1/2" | 14.4' | 32.1° | 90 | Pass |
| 17 | 6 3/8" | 12 1/4" | 16.4' | 28.8° | 90 | Issues |
| 18 | 6" | 13" | 18.4' | 26.0° | 90 | Issues |
| 19 | 5 5/8" | 13 5/8" | 20.4' | 23.8° | 90 | Issues |
| 22 | 4 7/8" | 14" | 24.5' | 20.2° | 86 | Issues |
| 14 | 7 3/4" | 10" | 10.8' | 39.7° | 81 | Pass |
| 23 | 4 3/4" | 14" | 25.7' | 19.3° | 78 | Issues |