Roof pitch = rise/run ratio. A 6/12 pitch means 6 inches rise per 12 inches of horizontal run.
6/12 pitch = 26.6° angle. 12/12 = 45°. 4/12 = 18.4°.
Pitch multiplier converts flat area to actual roof area: 6/12 pitch multiplier = 1.118.
This tool is most valuable when estimating materials for a full project scope. Run the calculation for each area or surface separately, then total the results to produce a complete materials list with a built-in waste allowance.
A common error is measuring irregular rooms or surfaces as simple rectangles. Recesses, alcoves, and non-right-angle corners require either decomposing the area into simpler shapes or using actual measured dimensions rather than approximations.
A builder quotes materials for a 120m² interior plastering job. The calculator estimates the plaster bags required at standard coverage rates, producing a materials list that prevents mid-project shortages and avoids the costly delays that result from underordering.
6/12 pitch = arctan(6/12) = arctan(0.5) ≈ 26.57 degrees.
CalcPlanet – Free Online Calculators
725+ free calculators and 108 tools for math, money, health, and everyday life. Instant results, verified formulas, no sign-up.
By CalcPlanet Editorial · Reviewed against our Editorial Standards and Formula Sources.
CalcPlanet calculators are free, privacy-first, and formula-reviewed.
Editorial Standards · Formula Sources · Privacy · Terms · Contact
