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Free Stair Calculator - Construction Made Easy

Calculate stair dimensions including rise, run, number of steps, and stringer length. Ensure building code compliance for safe, comfortable stairs.

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Calculate Stairs

Quick Answer

Standard stairs: 7" rise, 10-11" run. For 9 ft height: about 15-16 steps. Comfort formula: 2(rise) + run = 24-25 inches.

Key Facts about Stair Calculator:

  • Standard rise: 7-7.75 inches
  • Standard run: 10-11 inches minimum
  • All steps must be equal height
  • 2(rise) + run ≈ 24-25 inches
  • Stringer = √(rise² + run²)

Why Use Our Stair Calculator?

Complete stair calculations:

📏

Rise & Run

Optimal dimensions.

🔢

Step Count

Number of steps needed.

📐

Stringer Length

Calculate stringer cut.

Code Check

Building code compliance.

Instant Results

Get dimensions immediately.

🔒

100% Private

Your data stays private.

How to Stair Calculator in 3 Easy Steps

Calculate stairs:

1

Enter Height

Total rise to climb.

2

Set Parameters

Preferred rise/run.

3

Get Dimensions

See all stair specs.

Build Safe Stairs

Code-compliant design

Comfortable steps

Accurate measurements

Safe construction

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Safe Stairs
Code compliant

Common Use Cases for Stair Calculator

Perfect for:

DIY

Build your own stairs.

Calculate Stairs

Decks

Deck stair planning.

Plan Deck Stairs

Renovation

Replace stairs.

Plan Renovation

Frequently Asked Questions

Everything you need to know about our stair calculator

What is the ideal stair rise and run?

Rise: 7-7.75", Run: 10-11". Ideal: 7" rise, 11" run

Code typically requires: rise 7-7.75 inches, run 10-11 inches minimum. Ideal comfort: 7" rise, 11" run. Formula: 2(rise) + run should equal 24-25 inches.

How many steps do I need?

Total rise ÷ 7" ≈ number of steps

Divide total rise by ideal step height (7-7.5"). For 9 feet (108"): 108/7 = 15.4, so 15 or 16 steps. Then calculate exact rise per step.

How do I calculate stringer length?

Stringer = √(rise² + run²)

Use Pythagorean theorem: √(total rise² + total run²). For 9' rise and 12' run: √(81 + 144) = √225 = 15 feet stringer length.

Still have questions? Try the tool yourself!

Calculate Stairs

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