A 10 ft ceiling with 2x12 joists (132" floor to floor) needs 18 risers at 7-5/16" and 17 treads: a 170" run on 10" treads, cut from 20 ft 2x12s with 5-5/16" of throat. Gentler: 19 risers at 6-15/16" on 11" treads, a 198" run (2R + T = 24.9").
finished to finished
fewest legal
nosing to nosing
3/4–1-1/4 under 11″
DCA 6 max 18
132" total rise
Hook the tape once at mark 0, where the bottom riser line meets the top edge of the 2x12, and pencil every mark from that same hook. Each step is 12-3/8"+ along the edge; marks are rounded once each, so nothing drifts.
| Done | # | Mark | Tape | Decimal | mm |
|---|---|---|---|---|---|
| 0 | Bottom riser line | 0" | 0.000" | 0 mm | |
| 1 | Tread 1 nose | 12-3/8"+ | 12.401" | 315 mm | |
| 2 | Tread 2 nose | 24-13/16" | 24.801" | 630 mm | |
| 3 | Tread 3 nose | 37-3/16" | 37.202" | 945 mm | |
| 4 | Tread 4 nose | 49-5/8"− | 49.603" | 1260 mm | |
| 5 | Tread 5 nose | 62" | 62.004" | 1575 mm | |
| 6 | Tread 6 nose | 74-3/8"+ | 74.404" | 1890 mm | |
| 7 | Tread 7 nose | 86-13/16" | 86.805" | 2205 mm | |
| 8 | Tread 8 nose | 99-3/16"+ | 99.206" | 2520 mm | |
| 9 | Tread 9 nose | 111-5/8"− | 111.606" | 2835 mm | |
| 10 | Tread 10 nose | 124" | 124.007" | 3150 mm | |
| 11 | Tread 11 nose | 136-7/16"− | 136.408" | 3465 mm | |
| 12 | Tread 12 nose | 148-13/16" | 148.809" | 3780 mm | |
| 13 | Tread 13 nose | 161-3/16"+ | 161.209" | 4095 mm | |
| 14 | Tread 14 nose | 173-5/8" | 173.610" | 4410 mm | |
| 15 | Tread 15 nose | 186" | 186.011" | 4725 mm | |
| 16 | Tread 16 nose | 198-7/16"− | 198.411" | 5040 mm | |
| 17 | Top plumb cut | 210-13/16" | 210.812" | 5355 mm |
Then from mark 0 measure 6-1/4" down the bottom riser line and square across for the level heel cut.
Shortest run, steepest legal stair
Gentler climb, longer run
Floor to floor = ceiling + joists + subfloor. With 12-1/2" of floor framing and ceiling, the stairwell opening over Option A starts 43-7/8" from the bottom riser and runs 10' 6-1/8" for 6'-8" of headroom.
Sort any column, print a shop sheet, download CSV. Click a row to load it in the calculator.
| 0 | Bottom riser line | 0" | 0.000" | 0 mm | 0" |
|---|---|---|---|---|---|
| 1 | Tread 1 nose | 12-3/8"+ | 12.401" | 315 mm | 1' 3/8" |
| 2 | Tread 2 nose | 24-13/16" | 24.801" | 630 mm | 2' 13/16" |
| 3 | Tread 3 nose | 37-3/16" | 37.202" | 945 mm | 3' 1-3/16" |
| 4 | Tread 4 nose | 49-5/8"− | 49.603" | 1260 mm | 4' 1-5/8" |
| 5 | Tread 5 nose | 62" | 62.004" | 1575 mm | 5' 2" |
| 6 | Tread 6 nose | 74-3/8"+ | 74.404" | 1890 mm | 6' 2-3/8" |
| 7 | Tread 7 nose | 86-13/16" | 86.805" | 2205 mm | 7' 2-13/16" |
| 8 | Tread 8 nose | 99-3/16"+ | 99.206" | 2520 mm | 8' 3-3/16" |
| 9 | Tread 9 nose | 111-5/8"− | 111.606" | 2835 mm | 9' 3-5/8" |
| 10 | Tread 10 nose | 124" | 124.007" | 3150 mm | 10' 4" |
| 11 | Tread 11 nose | 136-7/16"− | 136.408" | 3465 mm | 11' 4-7/16" |
| 12 | Tread 12 nose | 148-13/16" | 148.809" | 3780 mm | 12' 4-13/16" |
| 13 | Tread 13 nose | 161-3/16"+ | 161.209" | 4095 mm | 13' 5-3/16" |
| 14 | Tread 14 nose | 173-5/8" | 173.610" | 4410 mm | 14' 5-5/8" |
| 15 | Tread 15 nose | 186" | 186.011" | 4725 mm | 15' 6" |
| 16 | Tread 16 nose | 198-7/16"− | 198.411" | 5040 mm | 16' 6-7/16" |
| 17 | Top plumb cut | 210-13/16" | 210.812" | 5355 mm | 17' 6-13/16" |
Step-off 12-3/8"+ (12.4007") · bottom cut 6-5/16" under 1" treads · last mark 17' 6-13/16" at the top plumb cut.
| 0 | Bottom riser line | 0" | 0.000" | 0 mm | 0" |
|---|---|---|---|---|---|
| 1 | Tread 1 nose | 13" | 13.010" | 330 mm | 1' 1" |
| 2 | Tread 2 nose | 26"+ | 26.020" | 661 mm | 2' 2" |
| 3 | Tread 3 nose | 39"+ | 39.031" | 991 mm | 3' 3" |
| 4 | Tread 4 nose | 52-1/16"− | 52.041" | 1322 mm | 4' 4-1/16" |
| 5 | Tread 5 nose | 65-1/16" | 65.051" | 1652 mm | 5' 5-1/16" |
| 6 | Tread 6 nose | 78-1/16" | 78.061" | 1983 mm | 6' 6-1/16" |
| 7 | Tread 7 nose | 91-1/16" | 91.072" | 2313 mm | 7' 7-1/16" |
| 8 | Tread 8 nose | 104-1/16"+ | 104.082" | 2644 mm | 8' 8-1/16" |
| 9 | Tread 9 nose | 117-1/16"+ | 117.092" | 2974 mm | 9' 9-1/16" |
| 10 | Tread 10 nose | 130-1/8"− | 130.102" | 3305 mm | 10' 10-1/8" |
| 11 | Tread 11 nose | 143-1/8" | 143.112" | 3635 mm | 11' 11-1/8" |
| 12 | Tread 12 nose | 156-1/8" | 156.123" | 3966 mm | 13' 1/8" |
| 13 | Tread 13 nose | 169-1/8" | 169.133" | 4296 mm | 14' 1-1/8" |
| 14 | Tread 14 nose | 182-1/8"+ | 182.143" | 4626 mm | 15' 2-1/8" |
| 15 | Tread 15 nose | 195-1/8"+ | 195.153" | 4957 mm | 16' 3-1/8" |
| 16 | Tread 16 nose | 208-3/16"− | 208.164" | 5287 mm | 17' 4-3/16" |
| 17 | Tread 17 nose | 221-3/16" | 221.174" | 5618 mm | 18' 5-3/16" |
| 18 | Top plumb cut | 234-3/16" | 234.184" | 5948 mm | 19' 6-3/16" |
Step-off 13" (13.0102") · bottom cut 5-15/16" under 1" treads · last mark 19' 6-3/16" at the top plumb cut.
05 / Field guide
This sheet works a 10-ft ceiling (132" floor to floor) two ways. Option A uses the fewest risers the IRC allows, 18 at 7-5/16" on 10" treads. Option B adds one riser and uses 11" treads for a gentler 6-15/16" step. Both come with hook-once tape marks for the stringer edge, below the calculator.
132" ÷ 7.75 = 17.03, rounded up to 18 risers, each 7-5/16"+ (7.3333", 186.3 mm). On 17 treads of 10" the stair lands 170" (14' 2") out from the upper floor edge and climbs at 36.3°; 2R + T scores 24.67".
Each step is 12-3/8"+ along the stringer edge. Notches cut 5-15/16" deep, leaving 5-5/16" of throat in a 2x12; the cut length is 17' 10-9/16", so buy 20 ft stock.
One more riser drops each step to 6-15/16" (6.9474"). With 11" treads the run grows to 198" (16' 6"), 28" more than Option A, and the angle eases to 32.3° with 2R + T at 24.89".
The diagonal is 13", the throat 5-3/8", and the stringer cut length 19' 9-3/8" (20 ft).
Take the tread thickness off the bottom riser: 7-5/16" becomes 6-5/16" under 1" 5/4 or composite treads, 5-13/16" under 1-1/2" 2x6 treads and 6-1/4" under 1-1/16" oak treads. Every finished step then measures 7-5/16".
At the top, the last tread notch sits 8-5/16" below the finished floor for 1" treads. Seated on a 2x header, the header top goes 16-1/8" below the finished floor with oak treads.
18 risers means a handrail is required (four or more risers), 34" to 38" above the nosings.
The 170" run is more than the 6'-0" a cut stringer may span under DCA 6: set 2 4x4 support posts on 12" footings under the stringers, or build a landing.
132" is 12" under the 12'-0" point where DCA 6 requires a landing on deck stairs, and 19" under the 151" IRC limit for one flight.
The IRC wants 6'-8" measured plumb from the nosing line. With 12-1/2" of floor framing and ceiling, the opening above Option A must start 43-7/8" out from the bottom riser and run 126-1/8" (10' 6-1/8") to the top of the stair.
This sheet assumes a 10 ft (120") ceiling plus 11-1/4" 2x12 joists and a 3/4" subfloor. With 2x10 joists the rise is 130"; use the converter in the calculator for your floor.
Questions
18 risers at 7-5/16" with 17 treads, the fewest the IRC allows. For an easier climb, 19 risers at 6-15/16" with 18 treads.
About 17' 10-9/16" along the board for Option A, so 20 ft 2x12s; Option B needs 19' 9-3/8" (20 ft).
170" (14' 2") on 10" treads, or 198" (16' 6") on 11" treads with 19 risers. Leave a landing at least 36" deep beyond the last riser.
A 120" ceiling over 2x12 joists and a 3/4" subfloor, or 122" over 2x10s. This is the standard 10 ft ceiling case.
Not under AWC DCA 6, which asks for 2x12s. A 2x10 would keep only 3-5/16" of throat on Option A, under the 5" minimum.
Enter your exact rise in the calculator. 126" takes 17 risers and 138" takes 18; the riser count changes wherever the rise passes a multiple of 7-3/4".
Raised decks, basements and storeys