Tread to Riser Ratio Calculator

Calculate the tread-to-riser ratio for stairs, ensuring optimal dimensions for safety and comfort. Supports metric (cm) and imperial (inches) units. Enter rise, tread, total rise, headroom, and mount type to compute ratios and check compliance with the golden rule (2R + T = 63 cm ± 1 cm). Results include stair visualizations in chart view by default.

Result

Detailed Steps

Stair Visualization

Formulas

Tread and Riser Calculations

Optimal tread for larger riser:

T = 20 – \frac{4R}{3}

Optimal tread for smaller riser:

T = 15 – \frac{3R}{4}

Golden rule for stair design:

2R + T = 63 \, \text{cm} \pm 1 \, \text{cm}

Tread to riser ratio:

\text{Ratio} = \frac{R}{T}

Where:

  • T = Tread (run, in cm or inches)
  • R = Riser (step height, in cm or inches)

Notes:

  • Metric: All measurements are converted to cm for golden rule checks.
  • Imperial: Converted to cm for golden rule, displayed in inches.
  • Typical values:
    • Riser: 6–8 inches (15–20 cm)
    • Tread: 9–11 inches (23–28 cm)
  • Headroom: Minimum 80 inches (203 cm) recommended.
  • Ratio > 1 indicates steeper stairs; < 1 indicates shallower stairs.

How to Use the Tread to Riser Ratio Calculator

  1. Select the unit system (Metric or Imperial).
  2. Choose run type (One Run or Total Run).
  3. Enter run (tread), total rise, rise (step height), headroom (optional), and mount type.
  4. Select display mode (Chart View is default).
  5. Click “Calculate” to view results, including optimal tread and riser, ratio, golden rule compliance, and stair visualizations.

Frequently Asked Questions (FAQs)

What is the tread to riser ratio?

The tread to riser ratio is the ratio of the riser height (R) to the tread depth (T), calculated as R/T. It indicates stair steepness.

What is the golden rule for stairs?

The golden rule states that 2R + T should equal 63 cm ± 1 cm, ensuring comfortable and safe stair dimensions.

How do I calculate optimal tread and riser?

Use T = 20 – (4R/3) for larger risers or T = 15 – (3R/4) for smaller risers. The calculator computes these automatically.

What is a good headroom value?

A minimum headroom of 80 inches (203 cm) is recommended for safety and comfort.

Why use the chart view?

It visualizes the stair profile with tread and riser dimensions, helping to understand the staircase design and ratio.