Support

Readings come from the phone's own motion sensors, so accuracy depends on the phone lying flat and still on a straight surface. Calibrating against a surface you trust removes the offset from the case and the bench. It works alongside a spirit level or a laser, not instead of one — for anything the Building Regs or a drawing depends on, confirm it with the instrument that drawing assumes.

Percentage, degrees, ratio (like 1:12 or 1 in 80) and fall per metre in millimetres. Imperial units are supported throughout, including inches per foot. You can enter a gradient in one notation and read it in any of the others.

No. Everything is calculated on the device from its own sensors. Your saved gradients and settings stay on your phone.

Yes. Anything where you need a specific angle rather than dead level. The presets cover the common trades, but you can set and save any gradient you like.