Rafter Length Converter
Convert rafter lengths between metric (metres) and imperial (feet, inches). Enter span and pitch in any unit and get results in both. Free, no signup.
Rafter / Hip & Valley
Calculate rafter and hip/valley lengths from pitch and span
Plan-view distance from wall to ridge (one rafter)
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Rafter conversion - did you know?
Metric to imperial
1m = 3.281ft = 39.37in. A 4.88m rafter = 16.01ft. Round up to next standard Imperial length when ordering.
Imperial to metric
1ft = 0.3048m. 1in = 25.4mm. A 16ft rafter = 4.877m. Verify converted length is available locally.
Converting pitch ratios
US: rise:12 (e.g. 6:12). To degrees: arctan(rise/12). UK degrees to US: tan(pitch°) × 12. At 35°: 8.4:12.
Standard timber lengths
UK: 4.8m, 5.4m, 6.0m. US: 12ft, 14ft, 16ft, 20ft. AU: 4.8m, 5.4m, 6.0m. Check local availability.
Formulas used
Metres → feet
feet = metres × 3.281
Feet → metres
metres = feet × 0.3048
Rafter (any unit)
rafter = run ÷ cos(pitch°)
US ratio → degrees
pitch° = arctan(rise ÷ 12)
Frequently asked questions
Convert rafter length metres to feet?
Multiply by 3.281. 4.88m = 16.01ft.
Convert 6:12 pitch to degrees?
arctan(6/12) = 26.57°. At 4m run: rafter = 4.47m.
Can I use imperial units?
Yes - toggle to Imperial, enter span in feet. Switch back for metric equivalent.
35 degrees as US ratio?
tan(35°) × 12 = 8.4, so 8.4:12.