Spirit level
Your phone as a level. Set zero on any surface, so the buttons and the case don't matter, then read the angle and how many mm to pack up the low end.
Your phone may ask to use motion. Tap Allow: nothing leaves your phone.
How to use it
- 01
Start it
Tap Start the level. An iPhone asks to use motion once each visit: tap Allow. Nothing leaves your phone.
- 02
On its edge or lying flat
Stand the phone on its long edge on whatever you are checking, or lay it flat on its back. It works out which, and keeps the screen on.
- 03
Set zero here
Put the phone on a surface and tap Set zero here. From then on it reads from that surface, so the buttons and the case stop mattering. Tilt it to match the surface, or to find an angle from it.
- 04
Flip check, for true level
Tap Flip check, turn the phone end for end on the same spot with the same edge down, then tap Second reading. The two readings cancel out the phone’s own error. It remembers the result for that edge.
- 05
How much to pack
Pick the length of what you are levelling: 600, 900, 1200 or 2400 mm. It says which end to raise and by how many mm.
- 06
Hold and Beep
Hold freezes the reading for when you can’t see the screen. Beep sounds each time it comes level (on an iPhone the ring switch has to be on).
How accurate is it?
A phone reads to about a tenth of a degree, which is about 1.7 mm over a metre. That's good for checking and setting out. For a long run, stand the phone on a straight edge and read that, and for the final fix check with a proper level.