ContractorHandbook

Stairs for a 6 Foot Rise: Risers, Treads and Stringer Length

Risers

10 at 7.2 in each

72 inches of total rise, 10.5 inch treads, 36 inch wide stairs.

total rise, intreadone risertotal rise / riser count = riser height, and it must come out equal
Total rise is fixed by the building, so the only free choice is how many risers to divide it into, and they must all come out identical. Code caps the riser and sets a minimum tread, and the stringer and headroom follow from both.

How that number is worked out

These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.

  • Total rise, finished floor to finished floor72 in
  • Tread depth you want10.5 in
  • Stair width36 in

Risers10 at 7.2 in each

Total rise72 in
Number of risers10
Riser height7.2 in
Number of treads9
Total run94.5 in (7.88 ft)
Stringer length, minimum9.9 ft
Headroom needed above nosing80 in minimum

The material list this produces

Stringers, 10 ft4
Treads, 36 in9
Risers, 36 in10

Tread depth compared

Deeper treads are more comfortable and eat more floor. Same rise, four tread depths.

Tread depthRisersTotal run
10 in10 at 7.2 in each90 in (7.5 ft)
10.5 in10 at 7.2 in each94.5 in (7.88 ft)
11 in10 at 7.2 in each99 in (8.25 ft)
11.5 in10 at 7.2 in each103.5 in (8.63 ft)

What else matters here

Ten risers at 7.2 inches is a comfortable flight, and the stairs run almost eight feet out from the top. That horizontal distance is what surprises people: a six foot rise needs eight feet of clear, level ground in front of it, plus the landing.

The cut stringer is nearly ten feet, which means 2x12 at twelve feet. Watch the throat: after cutting a 7.2 inch riser and a 10.5 inch tread out of a 2x12, the remaining solid wood behind the notch must stay at least five inches or the stringer is structurally wrong even though it looks fine.

At ten risers, most codes want the flight supported at the bottom on a concrete pad rather than on soil or a paver, and the stringers hung at the top from a properly fastened header rather than toenailed. Both details are load path, not finish.

What this calculator assumes

  • Riser count is the total rise divided by a 7.5 inch target, rounded to a whole number, and then increased by one if that would have put a riser over the code maximum. The rise is then divided evenly among them. Every riser in a flight must be within 3/8 inch of every other one.
  • Treads are always one fewer than risers when the top riser lands on the finished floor above.
  • The IRC limits are a 7.75 inch maximum riser and a 10 inch minimum tread. Your local code may be stricter, and commercial work certainly is.

Questions people ask

How many steps for a 6 foot rise?

Ten risers at 7.2 inches each, with nine treads.

How much space do 6 foot rise stairs need?

About 94.5 inches, just under eight feet, of horizontal run, plus a level landing at the bottom at least as deep as the stairs are wide.

What is stringer throat depth?

The solid wood left behind the notches. Most codes require at least 5 inches, and cutting deep treads out of a 2x12 can quietly drop below it.

Different numbers?

The stair calculator takes any dimensions you like and hands back the same list.

Other common sizes