FREE TOOL
Roof Tilt Calculator
Measure your roof's tilt from a photo. Take a photo of your house side on, drag the blue line along the roof edge and the green line along something you know is level, like a brick course or the gutter. The angle between them is your roof tilt. Your photo stays on your phone; nothing gets uploaded.
What is roof tilt?
Roof tilt (also called pitch) is the angle of the roof surface measured from horizontal. A flat roof is 0°, and most Australian hip and gable roofs sit between 15° and 25°, with 22.5° the most common on project homes. Builders sometimes quote pitch as a ratio like 5:12, which means the roof rises 5 units for every 12 it runs. This calculator gives you both.
How do I take a good photo?
Stand as square on to the end of the house as you can, so you're looking straight at the triangle of the gable. Hold the phone level and step back far enough that the whole roof line fits in frame. Then drag the blue line along the sloping roof edge and the green line along something that's level in real life: a brick course, the gutter, a slab edge or a fence rail. The longer you make each line, the more accurate the answer. With a good square on photo you'll land within 2 to 3° of the true pitch.
What's the best tilt for solar panels?
The rule of thumb says panels produce the most over a year when tilted at about the same angle as your latitude: 27° in Brisbane, 34° in Sydney, 38° in Melbourne. In practice panels almost always go flat against the roof, because tilt frames cost more than the extra energy is worth on a pitched roof. The good news is the difference is small. On a typical Australian roof anywhere from 15° to 30°, you're within a few per cent of the ideal.
Tilt matters less than direction, and both matter far less than every panel actually working. If you want the direction number too, use our Roof Azimuth Calculator.
Common questions
Is my photo uploaded anywhere?
No. The photo is processed entirely in your browser and never leaves your device. That's also why a shared link carries the measured angle but not the photo itself.
What if I can't get a square on photo?
The further off square you are, the more perspective skews the angle, so treat the result as a rough guide. The common pitch table is a solid fallback: most project homes built since the 1990s are 22.5°, skillion roofs usually run 1° to 5°, and older terracotta roofs often sit at 30° or steeper.
Does tilt matter as much as direction for solar?
Not quite. Direction shifts when you generate power through the day, while tilt mainly changes the balance between summer and winter output. Across the range of typical Australian pitches the annual difference is only a few per cent.
Can I use this on a flat or skillion roof?
Yes. Skillion roofs work especially well because the single roof line is easy to follow. For very low angles, take the photo from further back and use the longest level reference you can find.
Own solar already?
Your roof's tilt never changes, but a panel fault can appear any day and quietly cost you money for months. Solar Buddy connects to your inverter, learns how your system should perform and alerts you within 2 hours when something goes wrong.