Inclinometer
Turn your phone into a level
Allow motion access
This tool reads your device's tilt sensor. Nothing is recorded or sent anywhere — the readings stay in this browser tab.
About this tool
A digital level, inclinometer and plumb gauge using your phone's tilt sensor. Two-position calibration, auto-hold when steady, and readings in degrees, percent grade, roof pitch or rise-and-run.
Using the inclinometer
Three ways to measure
- Surface tilt: lay the phone flat on the surface to read how far it slopes from level, such as a floor, a deck, a roof or a bench.
- Plumb: hold the edge of the phone against a post, a wall or a door frame to read how far it leans from vertical.
- Angle between two surfaces: rest the phone on the first surface and capture it, then move it to the second. The reading is the angle between them, for example a wall against the floor or the two faces of a joint.
Why calibrate, and how it works
Almost every phone’s tilt sensor reads slightly off level when the phone is perfectly flat, and that built-in offset is added to every reading. Two-position calibration measures it: take one reading on any flat surface, then turn the phone round 180° on the same spot and take another. Turning it round reverses the surface’s own slope but not the sensor’s offset, so comparing the two readings separates them. The surface does not need to be level.
Calibration is stored on this device, so you only repeat it if you change phone or case. If you only have one surface you know is level, Zero on this surface is a quicker alternative.
Reading and holding the result
Show the slope in degrees, percent grade, roof pitch or rise and run, whichever your plans use; the slope calculator explains how they relate. Auto-hold freezes the reading once the phone is still, so you can measure under a sink or behind a beam and read the number afterwards. To set something to a given angle, enter a target: the display shows how far over or under you are, and supported phones vibrate on target.
Frequently asked questions
What is an inclinometer used for?
An inclinometer measures tilt: how far a surface slopes away from level, or how far something leans away from vertical. It is also called a tilt meter, clinometer or slope meter.
Builders use one to check roof pitch, ramps and drainage falls; mechanics and machinists use one to set blades, shafts and alignments; and it is just as handy for a sloping garden or the angle of a gym bench. Your phone can be one: lay it on the surface and read the angle on this page.
How does an inclinometer work?
An inclinometer compares the direction of gravity with its own base. Traditional ones use a weighted pointer or a bubble in a curved vial; digital ones use an accelerometer, a tiny sensor that detects which way is down.
When the base tilts, gravity acts on the sensor at a different angle, and the device turns that into degrees. Phones carry the same kind of accelerometer to rotate the screen, which is what lets a phone work as a digital level.
How do you use a digital inclinometer?
Calibrate it, place it against the surface you are measuring, and read the angle once the value settles.
On this page, run the two-position calibration once to remove your phone’s built-in offset. Then lay the phone on the surface, or hold its edge against a post in plumb mode. Auto-hold freezes the reading when the phone is still, so you can read it after lifting the phone from a spot you cannot see. The same slope can be shown in degrees, percent grade, roof pitch or rise and run.
To set something to a particular angle, give the inclinometer a target, such as 45°, and it shows how far off you are.
How accurate is a phone inclinometer?
Accurate enough for most building, DIY and gym jobs once it is calibrated, but it is not a substitute for a calibrated instrument. Before calibration, a phone’s sensor usually carries a built-in offset, often half a degree or more, and two-position calibration removes it.
After that, most of the error comes from what the phone rests on. A case, a camera bump or a rounded edge can tilt the phone by more than the sensor is off, so measure with a flat side of the phone on a clean surface and repeat the reading to confirm it. For structural, surveying or other safety-critical work, use a calibrated level.
Guides
About these measurements
Readings are estimates taken from rendered pixels and consumer device sensors. Do not rely on them for structural engineering, surveying, manufacturing inspection, navigation, or medical decisions. Check anything safety-critical with a calibrated instrument.
All processing happens in your browser. No image, camera frame or sensor reading is ever uploaded.
Other ways to measure
Slope calculator
Rise, run, length and grade
Enter any two of rise, run, sloped length and angle to solve the rest. See the slope as degrees, percent grade, a 1:N ratio, a pitch and per mille.
Camera measurement
Sight an angle through your camera
Aim your camera at a roofline, a tree or a slope and read the angle of elevation. Add the distance to work out the height, and hold the reading to note it down.
Roof pitch calculator
Pitch, degrees, rafters and roof area
Convert a roof pitch between x:12, degrees and percent, and get rafter and hip factors, cut angles, rafter length and roof area — with the minimum pitch for each roof covering from the International Residential Code.