Stair Calculator

Plan Your Perfect Staircase Dimensions

Input Mode

Dimensions

Total Rise (Floor to Floor Height)

Tread Run (Single Step Depth)

Advanced (Optional)

Target Step Rise

Standard building code max is ~7.75" (19.7cm).

Enter your total height (rise) and desired run to calculate the staircase.

Validation Error

Please check your inputs and ensure they are valid positive numbers.

Stair Terminology & Common Building Codes

Building a basic staircase may appear to be a simple carpentry task, but there are numerous mathematical parameters and strict building codes that must be followed. These range from the specific angle of inclination to how doors are placed in relation to landings. Below is a guide to standard stair terminology and building codes (always refer to your local specific municipal codes before building).

Run & Tread

The run or tread is the horizontal part of the stairway that a person steps on. Its length is measured from the outer edge of the step (including the nosing) to the vertical portion called the riser. When measuring the total run of a staircase, the tread above the last riser (the landing) is not included.

Code Suggestion: The tread should have a minimum depth of 10 inches (25.4 cm).

Rise & Riser

The rise is the vertical height of a single step, measured from the top of one tread to the top of the next tread. It is not simply the physical height of the riser board, because the calculation must include the thickness of the tread material. The total number of risers determines the number of steps.

Code Suggestion: The maximum height of a riser should be 7.75 inches (19.7 cm).

Nosing & Stringer

The nosing is the protrusion at the edge of a tread that hangs over the riser below. It improves safety by providing extra space for foot placement. A stringer is the structural member (usually 2x12 lumber) that supports the treads and risers.

Code Suggestion: Nosing typically must have a minimum length of 0.75 inches (1.9 cm) and a maximum of 1.25 inches (3.2 cm).

Headroom & Width

Headroom is the clearance measured from the top of a tread to the ceiling directly above it. Codes require significant headroom not just for tall people, but to allow for moving large furniture. Stair width is measured from edge to edge of the tread, excluding handrails.

Code Suggestion: Minimum headroom is generally 6 ft. 8 inches (203.2 cm). Minimum stair width is 36 inches (91.4 cm).

Handrails & Guards

A handrail runs up the stair incline for users to hold. A guard is a building component located near the open sides of elevated walking surfaces to prevent falls. Guards can be rails, walls, half-walls, or even sturdy benches.

Building codes generally require guards for stairs that have a total rise of more than 30 inches above the floor, and require that these guards be at least 34 inches (86.4 cm) in height. Similarly, handrails must be between 34 and 38 inches high, with a diameter between 1.25 inches (3.18 cm) and 2.675 inches (6.79 cm).

Fraction to Decimal Conversion

When dealing with imperial measurements in carpentry, converting 16ths, 8ths, and 4ths into exact decimals is frequently necessary. Use this quick reference table.

16ths	8ths	4ths	Halves	Decimal
1/16				0.0625
2/16	1/8			0.125
3/16				0.1875
4/16	2/8	1/4		0.25
5/16				0.3125
6/16	3/8			0.375
7/16				0.4375
8/16	4/8	2/4	1/2	0.5
9/16				0.5625
10/16	5/8			0.625
11/16				0.6875
12/16	6/8	3/4		0.75
13/16				0.8125
14/16	7/8			0.875
15/16				0.9375
16/16	8/8	4/4	2/2	1.0