Stair Rise Calc
Answer Worked out from a total rise of 96.00 inches, floor to floor.

Headroom calculator

Floor opening1479/16in147.6 in12 ft 3.58 in
Total rise
96in96.00 in8 ft
Headroom
80in80.0 in6 ft 8 in
The flight under the floor above. Headroom of 80.0 inches is measured straight up from the line through the step corners, and the opening in the 12.0 inch floor has to be 147.6 inches long to keep it. Headroom80 in Floor opening1479⁄16 in Floor12 in Total run143 in Clear from the top14.0 treads
Given

What this was worked out from

in
in
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These are the figures every number on this page is worked for.

Solution

Every dimension of this flight

To the nearest sixteenth
DimensionValue
Total rise 96in96.00 in8 ft
Risers 14
Riser height 67/8in6.857 in
Treads 13
Tread run 11in11.000 in
Total run 143in143.000 in11 ft 11 in
One step along the edge 1215/16in12.962 in
Marked length 1811/2in181.472 in15 ft 1.47 in
Stringer length 1721/4in172.235 in14 ft 4.24 in
Board length 16ft
Angle 31.9°
Stringer angle 33.9°
2 risers + 1 tread 2411/16in24.71 in2 ft 0.71 in
Bottom cut deduction 1in1.000 in
Tread thickness 1in1.00 in
Nosing 1in1.00 in
Stair width 36in36.00 in3 ft
Options

The clearance the opening has to keep

Headroom required
80in80.0 in6 ft 8 in
Clear from the top
14.0treads
Floor thickness
12in
Code

Each figure against the limit it has to meet

Dimension Limit Code Result
Riser height, maximum 73/4in IRC 2021 (residential) Within
Tread depth, minimum 10in IRC 2021 (residential) Within
Headroom, minimum 80in IRC 2021 (residential) Within
Stair width, minimum 36in IRC 2021 (residential) Within
Riser height, minimum 4in ADA 2010504.2 Within
Riser height, maximum 7in ADA 2010504.2 Within
Tread depth, minimum 11in ADA 2010504.2 Within
Nosing projection, maximum 11/2in ADA 2010504.5 Within
Calculators

Work out one part on its own

Source

Where the limits come from

2 sources, with the date each was read

Building codes are adopted and amended locally. Confirm every figure with the code your jurisdiction has adopted before you cut.

Updated September 2026