Construction calculators
Works in your browser. Nothing is uploaded.Rafter length calculator
Find a common rafter’s length from the span, pitch, overhang and ridge board, with the plumb and seat cut angles.
What to buy
–
Rafters–
- Ridge board–
ft
in 12
in
in
ft
Rafter length
–
Plumb cut
–
Seat cut
–
–
Construction calculators
ConcreteSlabs, footings and columns, in bags of your size.StairsRisers, treads and stringersDrywallSheets, screws and tapeTileTiles, adhesive and groutPaintCans for walls and ceilingsDeck boardsBoards, joists and screwsGravel and mulchBags or bulk for an areaBricks and blocksCount and mortar for a wallRoofingSquares, bundles and underlaymentRafter lengthFrom span, pitch and overhang
How to use it
- Type the span
The building’s width across the walls and the ridge board’s thickness.
- Set the slope
As a pitch in 12, an angle or a rise, and the overhang measured level.
- Mark and cut
Read the rafter length, then set your square or saw to the plumb and seat cut angles.
Tips
- Half the ridge
The run stops at the ridge board’s face, so half its thickness comes off each rafter.
- Speed square
Pivot a speed square to the roof angle to mark the plumb cut. The seat cut is square to it.
- Cut one first
Cut one rafter, try it on both sides of the roof, then use it as the pattern for the rest.
In the app
Construction tools in Clinometer
- Read the roof’s angle with the phone’s sensors
- A feet-inch-fraction job calculator with Rise, Run and Pitch keys
- Hip and jack rafters, with each jack’s length
- Shopping lists to tick off or send to To-do
Get it onGoogle PlayComing soon to the App Store
Construction tools guide ›