How to measure total rise
Record the whole flight from the finished floor you leave to the finished floor you reach.
Where the tape starts and stops
Total rise is the vertical distance for one flight. Set a level on the upper floor and drop a tape to the lower floor, then read the inches. Start on the finished floor you step off. Stop on the finished floor you step onto. Do not stop the tape on a threshold, a mat, or a loose board that will not be there when the stair is done.
If the finish is not installed, add its thickness to the lower reading, or measure to the subfloor and add the finish you will install. The stair calculator and the stringer calculator both expect that finished-to-finished number.
Both sides, then the taller one
Floors are rarely level across a stairwell. Measure the left side and the right side. Enter the taller one so every riser still fits the high side. A landing in the middle is a new flight: measure from the landing surface up to the next finished floor, and keep that rise separate.
On a deck, the same rule uses the finished decking and the finished landing. Do not measure from the top of a joist if the deck boards are not in that number, and do not stop on bare soil if a landing pad will raise the bottom.
Run and floor thickness are separate
Available run is the horizontal length you can give the stair, from the face of the first riser to the face of the upper floor. Measure it along the floor, not along the slope. Floor thickness is the upper floor from the finished surface down to the underside of the joists, including the subfloor and the finish. A 2x10 joist at 9 1/4 inches, plus a 3/4 inch subfloor, plus a 1/2 inch finish, is 10 1/2 inches. The opening length uses that thickness. Write the rise, the run, and the floor thickness before you pick a riser count.
A 108 inch rise with a 10 inch tread and a 10.5 inch floor is 14 risers at 7.714 inches, 13 treads, a 130 inch run, and a 117.3 inch opening.
Take that rise to the stair calculator for the riser count, the run, and the opening. The stringer layout guide is the next step when you are ready to mark the board.
This guide explains the measurement the calculators use. It is not a permit review.
Use it on a calculator
FAQ
Do I include the finish flooring?
Yes. Total rise runs from the finished surface you step off to the finished surface you step onto. If the tile or the hardwood is not down yet, add that thickness to a measurement that stopped on the subfloor. Mixing a subfloor at one end with a finished floor at the other changes every riser.
What if the two sides differ?
Measure both sides of the stairwell and keep the taller number. The risers have to clear the high side. A shorter measurement on the other side leaves the high side with a riser that is taller than the one you planned. Write both readings down, then enter the taller one.
Does a landing start a new rise?
Yes. Total rise is one flight, from the floor you leave to the floor or landing you arrive on. A landing in the middle ends that flight. Measure the next flight on its own, from that landing to the next finished floor. Do not add the two flights into one rise.
By Lumber Calc Editorial Team · Verified against 2021/2024 IRC & AWC DCA 6 · Last updated Oct 24, 2026