Why hook a tape instead of stepping the framing square along?

Every time the square is slid to the next step, the tread mark is lined up by eye on the last riser mark, and a hair of error comes along each time. Sixteen steps of a thirty-second each is half an inch at the top. The marks in the table are measured from one square end, so the last mark is exactly as good as the first. Use the square to draw each notch; use the tape to place it.

What is the drop, and why is the first riser cut short?

Every tread sits on top of the stringer, so it lifts every step by its own thickness — except the bottom one, which starts from the floor. Cut the first riser short by the tread thickness and every finished step comes out equal. Type your tread thickness in the field; type 0 if the treads sit flush or the bottom floor gets the same finish as the treads.

What is the throat, and how much do I need?

The throat is the board left under the notches, measured square to the edge — the board depth less the depth of each notch. This page measures it; it does not judge it. How much a stringer needs to keep, and what stock to use, is a structural question for your plans, your code or an engineer.

Where do the stair gauges go on the framing square?

The riser height on the tongue (the short, narrow leg) and the tread run on the blade (the long, wide leg), both on the outside edge. Lay the square on the board with both gauges tight to the top edge; the corner of the square is the inside corner of the notch.

How does this relate to the stair calculator?

It makes the same split — risers rounded from your target, every riser equal, one tread fewer than risers — so the riser and tread match what the stair calculator gives for the same rise. This page then turns the stair into a board: the marks, the cuts and the length of stock the stringer uses.

Stair stringer layout

Total rise (finished floor to finished floor)

Include flooring not laid yet. Inches, or feet-inches like 9' 1".

Target riser height

Rounded to equal risers, as on the stair calculator.

Tread run (going)

Riser face to riser face — not counting the nosing.

Stringer board depth (actual)

Measure the board: a 2×12 is 11¼ in, a 2×10 is 9¼ in.

Tread thickness (the drop)

The first riser is cut short by this. 0 for none.

— risers

Keep these results

We send this one email through our mail provider and don't keep your address.

Cutting sheet

Square the bottom end of the board. Hook the tape on that end and tick each mark on the top edge; then draw every notch with the framing square, both gauges tight to the edge, and the tread line through each mark.

Marks along the top edge
Mark	Tape from the square end	Finished step height

This is the geometry of the cut — marks, lengths and the board left under the notches. It does not size the stringer, space the stringers or say whether the stair will carry its load, and it does not replace your code’s riser, tread and headroom limits.

Type the rise and the riser and tread you want, then the board and the tread you are using. You get the framing-square settings, a tape mark for every step measured from one square end, the four cuts that are not notches (seat, first riser, top plumb, and the drop), the board the stringer uses, and a drawing to scale. Print it with the Print button and take the sheet to the saw.

Worked example

The stair calculator’s example: a 109 in rise at a 7 in target is 16 risers of 6 13/16″ (6.8125), 15 treads at 10½″. Set the gauges at 6 13/16 on the tongue and 10½ on the blade. Along the board’s edge each step is √(6.8125² + 10.5²) = 12 17/32″ (12.516) — a hair past 12 1/2.

The treads are 1 in thick, so the first riser is cut 6.8125 − 1 = 5 13/16″. Square the bottom end through the foot of that riser: the first mark is 5.8125 × 6.8125 ÷ 12.516 = 3 5/32″ up the edge, and each mark after is 12.516 further — mark 2 at 15 11/16, mark 3 at 28 3/16, on to mark 16 at 190 29/32″, the top of the last riser. That is the board the stringer uses: 15′ 10 29/32″, so a 16 ft 2×12 leaves 1 3/32″ to square the end.

The notches cut 6.8125 × 10.5 ÷ 12.516 = 5 23/32″ into a 11¼″ board, leaving a throat of 5 17/32″. The seat cut at the floor is 11 23/32″ long and the top plumb cut 13 13/32″.

In metric: 2,769 mm at a 178 target is 16 risers of 173 mm; at a 267 mm going each step is 318 mm along the edge. On a 286 mm board with 25 mm treads the first riser is cut 148 mm.

Try one

Quick referencefor laying out a stringer

Square: riser on the tongue, tread on the blade, gauges on the outside edges
Step on the edge: √(riser² + tread²) · 7 × 11 → 13.04 in · 178 × 279 mm → 331 mm
First riser: riser − tread thickness (the drop)
Notch depth: riser × tread ÷ step · throat = board − notch depth
Board used: first riser × riser ÷ step + (risers − 1) × step
Lumber: 2×10 = 9¼ in actual · 2×12 = 11¼ in (measure yours)

The formula

step = √(R² + T²) · notch = R·T ÷ step · mark k = (R − drop)·R ÷ step + (k − 1)·step

Questions

Why hook a tape instead of stepping the framing square along?: Every time the square is slid to the next step, the tread mark is lined up by eye on the last riser mark, and a hair of error comes along each time. Sixteen steps of a thirty-second each is half an inch at the top. The marks in the table are measured from one square end, so the last mark is exactly as good as the first. Use the square to draw each notch; use the tape to place it.
What is the drop, and why is the first riser cut short?: Every tread sits on top of the stringer, so it lifts every step by its own thickness — except the bottom one, which starts from the floor. Cut the first riser short by the tread thickness and every finished step comes out equal. Type your tread thickness in the field; type 0 if the treads sit flush or the bottom floor gets the same finish as the treads.
What is the throat, and how much do I need?: The throat is the board left under the notches, measured square to the edge — the board depth less the depth of each notch. This page measures it; it does not judge it. How much a stringer needs to keep, and what stock to use, is a structural question for your plans, your code or an engineer.
Where do the stair gauges go on the framing square?: The riser height on the tongue (the short, narrow leg) and the tread run on the blade (the long, wide leg), both on the outside edge. Lay the square on the board with both gauges tight to the top edge; the corner of the square is the inside corner of the notch.
How does this relate to the stair calculator?: It makes the same split — risers rounded from your target, every riser equal, one tread fewer than risers — so the riser and tread match what the stair calculator gives for the same rise. This page then turns the stair into a board: the marks, the cuts and the length of stock the stringer uses.

Related tools

Spot something wrong on this page? Report it

Thanks — your report was sent.

That didn’t send. Please try again later.