Roof Truss Calculator

0.0(0)

Calculates rafter length and the estimated number of roof trusses needed based on roof dimensions and truss spacing.

How To Use

How to use this calculator

Start with your values, or try a preset.

Step 1

Enter Roof Length (ft), Roof Width (ft), Roof Pitch (rise/12), Truss Spacing (in), and Overhang (ft) in the units shown.

Step 2

Read Number of Trusses and Rafter Length (ft) in the results panel. Results update as you change the inputs.

Step 3

Choose a preset to load an example, then adjust the values for your situation.

Worked Examples

See the inputs and their calculated results.

Roof Length (ft): 12 ft; Roof Width (ft): 10 ft; Roof Pitch (rise/12): 4; Truss Spacing (in): 24 in; Overhang (ft): 1 ft

Number of Trusses: 7 trusses; Rafter Length (ft): 6.270462767 ft

Roof Length (ft): 24 ft; Roof Width (ft): 24 ft; Roof Pitch (rise/12): 6; Truss Spacing (in): 24 in; Overhang (ft): 1 ft

Number of Trusses: 13 trusses; Rafter Length (ft): 14.41640786 ft

Roof Length (ft): 30 ft; Roof Width (ft): 28 ft; Roof Pitch (rise/12): 8; Truss Spacing (in): 16 in; Overhang (ft): 1 ft

Number of Trusses: 24 trusses; Rafter Length (ft): 17.82590595 ft

People Also Calculate

Continue with another tool on a related topic.

Estimates how many items or boxes fit on a standard pallet or how many pallets are needed for a shipment.

Calculates the number of light bulbs needed to adequately illuminate a room based on its dimensions, desired light level, and bulb specifications.

Converts a decimal inch measurement into its equivalent fractional representation (inches and fractions of an inch).

Calculates the taper length and angle based on the large diameter, small diameter, and taper length.