Roof Pitch Calculator
Angle, slope and rafter length conversions
Pitch converter
Edit any field — the others update instantly.
Rafter length
Uses the current pitch to size the rafters of a symmetric gable roof.
Rafter length is given per side, measured along the slope including the overhang.
About Roof Pitch Calculator
The roof pitch calculator converts between every way of expressing a roof slope: the angle in degrees, the slope as a percentage, the rise per 12 units used in North America (a “6/12 roof”), and the rise per meter used in metric practice. Edit any one field and the other three update instantly.
It also sizes the rafters of a symmetric gable roof. Enter the building span — outside wall to outside wall — and the eaves overhang, and the tool applies the current pitch to return the rafter length per side, measured along the slope including the overhang, plus the ridge height above the wall plate.
Roofers, framers, and DIYers use it to translate a plan angle into a cut length, order rafter stock, or compare pitches before choosing a roofing material. Quick-pick buttons load the common pitches, a live gable-section diagram shows the geometry, and everything runs free in your browser.
How to use Roof Pitch Calculator
- Type a value into any converter field — angle, slope %, rise per 12, or rise per meter — and watch the others update.
- Or tap one of the common pitch quick-picks to load it.
- For rafter sizing, enter the building span in meters and the eaves overhang in centimeters.
- Read the rafter length per side and the ridge height, and check the gable-section diagram.