Staircase Dimension Calculator

Calculate riser height, tread count, and total run for your next project.

Total Rise (Floor to Floor height) The vertical distance between levels.

Target Riser Height Standard is usually around 7 inches.

Tread Depth The depth of the step surface.

Units Inches Centimeters

Calculation Results

Number of Risers:

Actual Riser Height:

Number of Treads:

Total Run:

Stair Angle: °

Stringer Length:

How to Use the Stairs Calculator

Planning a staircase requires precision to ensure safety and compliance with local building codes. This tool calculates the exact dimensions needed for stringers, risers, and treads based on your total floor-to-floor height.

Key Definitions

Total Rise: The total vertical distance between the top of the lower floor and the top of the upper floor.
Riser Height: The vertical height of each individual step. Codes typically limit this to a maximum of 7.75 inches.
Tread Depth: The horizontal depth of each step where you place your foot. Codes typically require a minimum of 10 inches.
Total Run: The total horizontal distance the staircase covers.

The "7-11" Rule

A common rule of thumb in carpentry is the "7-11" rule: a 7-inch riser and an 11-inch tread. This generally results in a comfortable stair angle of roughly 32 to 37 degrees. If your space is tight, you may need a steeper angle, but always check local regulations regarding the "Stringer Rule" (Rise + Run should equal between 17 and 18 inches).

Example Calculation

If your total rise is 100 inches and your target riser height is 7 inches:

100 / 7 = 14.28. We round up to 15 risers.
100 / 15 = 6.67 inches (Actual Riser Height).
Number of treads = 15 – 1 = 14 treads.
If tread depth is 10.5 inches, Total Run = 14 * 10.5 = 147 inches.

function calculateStairs() { var totalRise = parseFloat(document.getElementById('totalRise').value); var targetRiser = parseFloat(document.getElementById('targetRiser').value); var targetTread = parseFloat(document.getElementById('targetTread').value); var unit = document.getElementById('unitType').value; if (isNaN(totalRise) || totalRise <= 0 || isNaN(targetRiser) || targetRiser <= 0 || isNaN(targetTread) || targetTread <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Number of risers must be an integer. We round the division result. var numRisers = Math.ceil(totalRise / targetRiser); var actualRiserHeight = totalRise / numRisers; // In most standard stairs, the top tread is the floor of the second level, // so there is one fewer tread than there are risers. var numTreads = numRisers – 1; var totalRun = numTreads * targetTread; // Calculate Angle: tan(theta) = Rise / Tread var angleRad = Math.atan(actualRiserHeight / targetTread); var angleDeg = angleRad * (180 / Math.PI); // Calculate Stringer Length using Pythagorean theorem on the total triangle var stringerLength = Math.sqrt(Math.pow(totalRise, 2) + Math.pow(totalRun, 2)); // Display results document.getElementById('resRisers').innerText = numRisers; document.getElementById('resRiserHeight').innerText = actualRiserHeight.toFixed(3) + " " + unit; document.getElementById('resTreads').innerText = numTreads; document.getElementById('resTotalRun').innerText = totalRun.toFixed(2) + " " + unit; document.getElementById('resAngle').innerText = angleDeg.toFixed(2); document.getElementById('resStringer').innerText = stringerLength.toFixed(2) + " " + unit; document.getElementById('stairResults').style.display = 'block'; }