STR

Stair Calculator

Risers, treads, total run and stringer length for a straight stair, checked against typical code limits.

Construction & GeometryTop 100 · #79Runs in your browser

Result…

Units
mm
mm

The tallest riser you want; the stair is divided so no riser is taller.

mm

The horizontal going of each step, without the nosing.

 

…

How it's calculated

Risers = total rise ÷ max riser, rounded up
Riser = total rise ÷ risers
Treads = risers − 1
Total run = treads × tread depth
Stringer = √(total rise² + total run²)

Divides a floor-to-floor height into equal risers no taller than you choose, then gives the treads, the total horizontal run and the length of the stringer along the slope. It checks the result against typical residential limits (riser at most 7¾ in / 197 mm, tread at least 10 in / 254 mm); codes differ by country and region, so check yours. Cut stringers from a board longer than the stringer length.

Your numbers, step by step

    More in Construction & Geometry

    m³ConcreteThe concrete for a slab or round columns, in cubic metres or yards and in premix bags.Top 100 · #72ft²Square footageThe area of a room or plot in square feet and square metres, with an optional cost.Top 100 · #73LPaintThe paint for a room's walls (and ceiling), less doors and windows, for the coats you will apply.Top 100 · #74TILTilesHow many tiles (and boxes) to cover a floor or wall, with a waste allowance.Top 100 · #75FLRFlooringThe boxes of laminate, vinyl or wood flooring for a room, with waste and an optional cost.Top 100 · #76BRKBricksThe bricks for a single-leaf wall from its size, the brick and the mortar joint.Top 100 · #77