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How to Measure Stair Rise Accurately

Every number in a stair plan comes from one measurement: the total rise. Get it wrong and every riser is wrong. Here is how to measure it, and the mistakes that quietly spoil it.

Published 2026-10-24 by Blissom Apps · How we write and check guides

What total rise means

Total rise is the vertical distance from the lower finished floor to the upper finished floor, measured where the stair will actually stand. "Finished" means the surface you will walk on: hardwood, tile, carpet pad and all. It is not the floor-to-ceiling height, not the height of the framing, and not the sum of the risers on an old stair, which may not be equal.

The calculator divides this one height into equal risers, so an error here is shared out over every step, which is forgiving. Errors in the finishes are not shared: they land entirely on the first or last step, which is why they matter more (see the example below).

What you need

  • A tape measure you trust, ideally one that reads in sixteenths, or a metric tape in millimetres.
  • A straight board long enough to reach from the upper floor out over the opening (8 to 12 ft for a typical stair), and a level to set on it. A laser level or a water level does the same job over longer distances.
  • A helper, and a pencil to mark the floor where the stair will land.
Measuring total rise with a level straightedgeA straight board rests on the upper finished floor and extends level over the stair opening. The total rise is measured straight down from the underside of the board to the lower finished floor at the point where the bottom riser will land, about one stair run away from the upper floor edge, not directly below the edge. The lower floor slopes slightly, so the two measurements differ.finished floorsubfloorframinglevelstraight boardlower floor, slope exaggeratedfuture tile? include ittotal rise: measure herewhere the bottom riser will landnot straight below the edgeabout one stair run
Measure from the upper finished surface (the underside of a level board resting on it) down to the lower finished surface at the landing point. The slope is exaggerated to show why the spot matters.

Step by step

  1. Estimate where the stair lands. A rough rise is enough for this. For a 9 ft floor-to-floor height, a stair with 10 1/2 in goings runs about 11 ft 4 in, so the bottom riser lands about that far from the upper floor edge. Run the stair calculator with a rough figure and mark the spot.
  2. Bridge the opening with a level reference. Rest the straight board on the upper finished floor so that it projects out over the landing spot. Put the level on it and shim the board until it reads level. With a laser, set it to project a level line at a known height above the upper floor instead.
  3. Measure down at the landing spot. Measure from the underside of the board, which is level with the upper floor surface, straight down to the lower floor at your mark. Keep the tape plumb. That is the total rise.
  4. Repeat across the width. Measure at both sides of where the stair will be. If the readings differ, the lower floor slopes across the stair. Note both; you will plan with one value and level the landing area, or shim under the stringers so treads end up level.
  5. Check the landing spot again. Put the measured rise into the calculator. If the run changes enough to move the landing point onto a noticeably different floor height, measure again at the new spot. On level floors one pass is enough; on slopes, see the deck stair calculator, which solves this for you.

When the floors are not finished yet

On new construction you often measure subfloor to slab. Convert it to a finished rise before you plan:

finished rise = measured rise + thickness to be added on the upper floor − thickness to be added on the lower floor

Example. You measure 107 1/4 in from the upper subfloor to the basement slab. The upper floor will get 3/4 in hardwood; the basement will get tile on a thin-set bed totalling 1/2 in. Finished rise = 107.25 + 0.75 − 0.5 = 107.5 in. Plan the stair from 107.5 in, then use the stringer calculator's "floor finish added at the bottom later" option so the first riser cut accounts for the tile.

Why a forgotten finish breaks the stair

Suppose you plan 14 equal risers from a 108 in rise, so each is 7.714 in, and the 3/4 in hardwood on the upper floor goes down after the stair is built. Your top riser is now 7.714 + 0.75 = 8.46 in while the others stay 7.714 in. That 0.75 in difference is double the 3/8 in maximum variation that the IRC allows between the tallest and shortest riser in a flight (2024 IRC R318.7.5.1; R311.7.5.1 in 2021). It is also the step people trip on, because feet expect every riser to be the same.

Replacing an existing stair

Do not add up the old risers. They may not be equal, and the old stair may have been built before a floor finish changed. Measure floor to floor with a level reference as above. If the old stair is still in place, you can rest the board on the top nosing line instead, but check that the top tread is level with the upper floor first.

Decks and outdoor steps

Measure from the top of the decking. Ground usually slopes away from the house, so the landing point is lower than the ground under the deck edge, and a pad or pavers raise it again. The deck stair calculator takes the deck height, the slope and the pad height and finds where the stair really lands.

Checklist of measuring mistakes

  • Measuring straight down from the upper floor edge instead of at the landing point.
  • Measuring from the subfloor, or to a slab, without adding or subtracting the finishes.
  • Letting the tape lean, which adds length. Keep it plumb, or use a laser distance meter held against a level.
  • Reading the tape from the wrong end of the hook on an inside measurement.
  • Forgetting carpet: the IRC measures risers and treads without carpet, rugs or runners (2024 R318.7.5), but thick pad can still change how the top step feels.
  • Measuring once. Measure twice at each side, and again after any floor work.