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Roof pitch calculator

Turn a roof's rise and run into an angle, a percentage and an X:12 pitch.

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Need Angle (°), Slope (%), Pitch (x-in-12)? The Roof pitch calculator derives it from Rise (cm), Run (cm) in one step. For instance, with Rise (cm) = 30 and Run (cm) = 100 it returns Angle (°) = 16.699, Slope (%) = 30% and Pitch (x-in-12) = 3.6.

How to use it

  1. Enter your values: Rise (cm), Run (cm).
  2. Read the result instantly: Angle (°), Slope (%), Pitch (x-in-12).

Frequently asked questions

How does the Roof pitch calculator work?

It takes Rise (cm) and Run (cm) and derives Angle (°), Slope (%) and Pitch (x-in-12) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

2 values: Rise (cm) and Run (cm). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Rise (cm) = 30 and Run (cm) = 100, the calculator returns Angle (°) = 16.699, Slope (%) = 30% and Pitch (x-in-12) = 3.6. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

When would I actually use this?

Buying the right amount at the merchant: how many tiles, how much paint, how many bags of concrete, and what it all comes to.

What is the most common mistake?

Ordering the exact calculated quantity. Every material loses some of itself between the pallet and the finished job — offcuts, breakage, a bag that sets, a coat that soaks in further than the datasheet says — so add the allowance yours asks for, and order it in one delivery: a second batch rarely matches the first.

Where do the figures come from, and how current are they?

The geometry is exact for the dimensions you enter. Coverage rates come from manufacturer datasheets and vary with the surface, the number of coats and how absorbent the substrate is.

Further reading

All guides →
How-toHow to Measure Roof PitchRoof pitch is rise over run, like 6:12. Here's how to measure it with a level, how to convert it to an angle or percentage, and why it matters.GuideEstimating a Beam's Safe Load: Span, Deflection and the Load CaseA calculator gives you an order of magnitude, and anything holding up a floor, a roof or people needs an engineer and a code check. Between those two facts there is a great deal worth knowing: which power of the span the deflection really follows, which loading case the tool assumes, and what L/360 is in fractions of an inch on a span you can measure.GuideWhat a Steel Plate, Bar or Tube Weighs — And What the Number Is ForSection area times length times density, for nine profiles and fourteen metals. What the calculator returns, why one figure covers every carbon-steel grade, and the two places its geometry is not the merchant's geometry.ExplainerTightening a Bolt to the Right Torque: Why the Number on the Wrench Is a GuessTorque does not hold a joint together — preload does, and torque is a poor proxy for it. Here is where 90 % of your effort goes, what the K-factor really is, and why the same 37.84 N·m gives anything from 12.61 kN to 37.84 kN of clamping force.GuideHow Much Lumber a Project Needs — And Why a 2×4 Isn't OneCount pieces first, then linear feet, then board feet. A 2×4 measures 1½ × 3½ inches but is billed on the full 2 × 4 — 34 % of what you pay for is sawdust. Worked from the calculator's real output, with the waste rule it actually applies.How-toHow to Calculate a Staircase: Risers, Treads and the Rule That Ties Them TogetherA 110 in rise divided by a 7 in target gives 15.7 risers. You round to 16 and divide again, landing on 6 7/8 in. Here is the whole method, and why the building codes do not agree with each other.