Framing Calculator
Framing calculator works out Pieces needed and Pieces from the spacing alone from What to count, Wall length (or roof length for rafters) and Unit for lengths. The default figures on this page give pieces needed of 16; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Layout: floor(240 in / 16 in) + 1 = 16 studs per wall, x 1 wall(s) = 16.
- Extras: 0 corner(s) x 2 + 0 intersection(s) x 2 + 0 opening(s) x 4 = 0.
- Total studs = 16 + 0 = 16.
- Plates: one bottom plate and a double top plate, so 3 x 20 ft x 1 = 60 linear feet.
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the framing calculator calculates
Counts wall studs at 12, 16, 19.2 or 24 inches on centre with corner, intersection and opening allowances plus plate material, and computes common rafter length, count and cut angles from the roof pitch and span.
How to use this framing calculator
Enter What to count, Wall length (or roof length for rafters), Unit for lengths and Spacing on centre. Pieces needed updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Pieces needed, Pieces from the spacing alone and Extra pieces for corners, intersections and openings.
The method follows International Residential Code (IRC), Chapter 6 Wall Construction and Chapter 8 Roof-Ceiling Construction, Pythagoras: a common rafter is the hypotenuse of the run and the rise and US Department of Commerce Voluntary Product Standard PS 20, American Softwood Lumber Standard.
20 ft wall at 16 in on centre example
With What to count: stud, Wall length (or roof length for rafters): 20, Spacing on centre: 16, the calculator returns Pieces from the spacing alone: 16, Pieces needed: 16, Plate material (bottom plate plus double top plate): 60. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Pieces needed, Pieces from the spacing alone and Extra pieces for corners, intersections and openings. The inputs you can vary are What to count, Wall length (or roof length for rafters), Unit for lengths, Spacing on centre, Number of identical walls and Corners.
Understanding Pieces needed, Pieces from the spacing alone and Extra pieces for corners, intersections and openings
A quantity and geometry take-off only. It does not size any member and does not check spans, loads, bracing, uplift connections or header sizes; those must come from a licensed engineer’s design or from the prescriptive span tables of the code adopted where you build (e.g. IRC Tables R602.3(5) and R802.4).
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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Frequently asked questions
How do I calculate how much lumber I need for framing?
Counts wall studs at 12, 16, 19.2 or 24 inches on centre with corner, intersection and opening allowances plus plate material, and computes common rafter length, count and cut angles from the roof pitch and span. Open “How this is worked out” beside the result to see each step for your own figures.
What information do I need for the framing calculator?
You need What to count, Wall length (or roof length for rafters), Unit for lengths, Spacing on centre, Number of identical walls, Corners, Extra studs at each corner and Partition intersections. The page opens with default figures that give pieces needed of 16, so you can see the scale before entering your own.
What does this framing calculator show?
It shows Pieces needed, Pieces from the spacing alone, Extra pieces for corners, intersections and openings, Plate material (bottom plate plus double top plate), Rafter length including overhang, Rafter line length, ridge to plate, Rafter run and Rafter rise, with the working and any warnings for your entries.
Can I check how the framing calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.