Staircase Calculator

Staircase calculations determine the number of steps, total run, and angle based on floor-to-floor height and desired riser height.

Number of Risers = Floor Height / Riser Height (rounded up)

Actual Riser Height = Floor Height / Number of Risers

Total Run = Number of Treads × Tread Depth

Note: Number of treads = Number of risers - 1 (the top floor acts as the last tread).

Stair Angle = arctan(Riser Height / Tread Depth)

Building code guidelines (imperial):

• Maximum riser height: 7.75 inches (residential)
• Minimum tread depth: 10 inches (residential)
• Comfortable riser: 7 – 7.5 inches
• Comfortable tread: 10 – 11 inches
• The “rule of 17”: riser + tread should be about 17 inches

Building code guidelines (metric):

• Maximum riser height: 200 mm (20 cm) (residential)
• Minimum tread depth: 250 mm (25 cm) (residential)
• Comfortable riser: 175 – 190 mm
• Comfortable tread: 250 – 280 mm
• The “rule of 430 mm”: riser + tread should be about 430 mm

Comfortable stair angle: 30° – 37° is ideal for residential stairs.