Stud Calculator
Framing a wall starts with an accurate lumber count. This stud calculator figures out how many studs you need from the wall length and your on-center spacing, then adds the standard extras for door and window openings and corners. It also totals the linear feet of plate lumber for the top and bottom plates, so you leave the lumber yard with a complete cut list.
Measured along the bottom plate line.
Used for the wall-area reference row.
16″ oc is standard for load-bearing walls.
Each opening gets extra king and jack studs.
Inside and outside corners need nailing studs.
Studs needed
26
- Wall studs (straight run)
- 16
- Extra studs — openings & cornersKing/jack studs and corner nailing (rule of thumb)
- 10
- Plate lumber (top + bottom)Double top plate: 3 × wall length
- 40ft
- Wall area (for sheathing)
- 160ft²
How it was calculated
- Wall studs = ⌈(20 × 12) ÷ 16⌉ + 1 = 16 studs at 16″ on center
- Extras = 1 openings × 2 + 4 corners × 2 = 10 studs (rule of thumb)
- Total studs = 16 + 10 = 26
- Top + bottom plates = 2 × 20 = 40 linear ft
- Double top plate (if required by code/plan) = 3 × 20 = 60 linear ft
- Wall area = 20 × 8 = 160.0 ft² (handy for sheathing)
How it works
Stud bays: wall length in inches ÷ on-center spacing, rounded up, plus one starter stud. A 20-ft wall at 16″ on center needs ⌈240 ÷ 16⌉ + 1 = 16 studs for the straight run.
Openings and corners each get 2 extra studs — king plus jack studs at openings, extra nailing studs at corners. This is the standard framing rule of thumb used by most carpenters for a quick takeoff.
Plates: bottom plate plus top plate = 2 × wall length in linear feet. Where the plan or code calls for a double top plate, allow 3 × wall length instead.
Worked examples
20-ft wall, 16″ oc, one door, four corners
Straight run: ⌈240 ÷ 16⌉ + 1 = 16 studs. Extras: 1 × 2 + 4 × 2 = 10 studs. Total: 26 studs. Plates: 2 × 20 = 40 linear ft. Wall area: 20 × 8 = 160 ft² if you also need sheathing.
12-ft partition wall, 24″ oc, two windows, two corners
Straight run: ⌈144 ÷ 24⌉ + 1 = 7 studs. Extras: 2 × 2 + 2 × 2 = 8 studs. Total: 15 studs. Plates: 2 × 12 = 24 linear ft — a noticeably smaller lumber bill than 16″ spacing.
How to measure
- Measure wall length along the bottom plate line, from the outside of one corner to the outside of the other.
- Confirm spacing with local practice: 16″ on center is standard for load-bearing walls, while 24″ is common for non-bearing partitions.
- Count every door and window opening separately — each one needs king and jack studs.
- Count both inside and outside corners; each needs extra studs to give drywall something to nail to.
- Buy studs pre-cut to your wall height (for example, 92⅝″ precuts for 8-ft walls with plates) to skip ripping every stud.
Assumptions & limitations
Planning estimate
- Extras of 2 studs per opening and 2 per corner are a framing rule of thumb; complex headers or California corners may need more.
- The plate figure covers a single top plate plus the bottom plate; double top plates common on load-bearing walls need 3 × wall length, as noted in the steps.
- Cripple studs above and below openings are approximated inside the extras; very tall walls or many small windows deserve a manual count.
- This is a planning estimate only — not a substitute for code compliance or professional design. Verify spacing, headers, and plate requirements against your local building code.
Frequently asked questions
A 12-ft wall at 16 inches on center needs 10 studs for the straight run (⌈144 ÷ 16⌉ + 1), before openings and corners. Add 2 per door or window and 2 per corner. Most 12-ft partition walls with one door land around 14–16 studs total.
It means the distance from the center of one stud to the center of the next is 16 inches. This spacing lines up with 4-ft-wide sheathing and drywall so that panel edges always land on a stud. It is the standard for load-bearing residential walls in the US.
Most codes require a double top plate on load-bearing walls to tie the framing together and carry loads across the studs. Non-load-bearing partition walls often get by with a single top plate. Check your local code — the calculator shows the 3 × length figure in the steps when you need it.
Plan on 2 extra studs per door: a king stud running full height plus a jack stud carrying the header. A 10-ft wall at 16″ on center with one door works out to ⌈120 ÷ 16⌉ + 1 = 9, plus 2 = 11 studs before corners. Do not forget the header lumber above the door itself.
On non-load-bearing interior walls, 24″ on center is often allowed and uses noticeably fewer studs. Load-bearing walls, tall walls, and walls carrying tile or other heavy finishes usually require 16″. Confirm with your local building code before widening the spacing.