Free Online Tool · India · Metric & Imperial
Roof Pitch Calculator India — Pitch, Angle & Slope
Built for Indian builders, contractors and homeowners. Enter the rise and run of your roof in millimetres or inches and get the pitch ratio, the angle in degrees, the slope percentage and the roof pitch multiplier instantly.
Roof Pitch Calculator
LIVE RESULTStandard run = 1000 mm
Conventional / standard slope
Drag the orange apex to change both rise and run, or the blue handles to adjust one at a time. The boxes above stay in sync.
Tip: the calculator updates as you type. Most Indian house roofs and sloped RCC roofs are designed between a 2:12 and 6:12 pitch.
What Is Roof Pitch?
Roof pitch describes how steep a roof is, written as rise over run — the vertical height the roof gains over a fixed horizontal distance. In India both metric (mm and metres) and the traditional X:12 ratio are used, so this roof pitch calculator supports both.
Pitch vs. Slope
The terms pitch and slope are now used interchangeably and both are based on rise over run. A flatter slope is common on RCC roofs, while sloped tile and Mangalore-tile roofs use steeper pitches to shed monsoon rain quickly.
How to Calculate Roof Pitch
The Basic Pitch Formula
Roof Pitch in Degrees
Example: a roof rising 500 mm over a 1000 mm run has an angle of arctan(0.5) = 26.57°.
Roof Pitch Multiplier
Multiply the plan (flat) area of the building by the multiplier to estimate the sloped roof surface area for ordering tiles or sheets.
Roof Pitch Chart
| Pitch (X:12) | Angle | Slope % | Multiplier |
|---|---|---|---|
| 1:12 | 4.76° | 8.3% | 1.0035 |
| 2:12 | 9.46° | 16.7% | 1.0138 |
| 4:12 | 18.43° | 33.3% | 1.0541 |
| 6:12 | 26.57° | 50% | 1.1180 |
| 12:12 | 45.00° | 100% | 1.4142 |
Frequently Asked Questions
What roof pitch is common in India?
Sloped tile and metal-sheet roofs are often between 2:12 and 6:12. Steeper pitches drain heavy monsoon rain faster.
How do I convert 5 degrees to a roof pitch?
A 5 degree pitch rises about 9 mm per 100 mm of run, roughly 87 mm per metre — close to a 1:11.4 ratio.
Is pitch the same as roof angle?
They are the same slope shown differently — pitch as a ratio, angle in degrees via the arctangent function.