Protractor

Protractor & Angle Finder turns your phone into a two-in-one drafting instrument. Measure angles two ways: with an on-screen protractor you align by hand, or with a sensor inclinometer that reads the real tilt of a surface.

ON-SCREEN PROTRACTOR

• A graduated 0-180° protractor dial with fine degree ticks

• Two draggable arms — set them to any angle and read the degrees live

• Instant complement angle for quick geometry, carpentry and DIY

• Reset to a clean 90° base with one tap

SENSOR INCLINOMETER (ANGLE FINDER)

• Uses the accelerometer to read the tilt of a real surface

• Large degree readout plus slope percentage

• Zero-to-surface calibration so you can measure relative angles and bevels

• Handy for shelves, ramps, roofs, furniture, camera setups and levelling

BUILT FOR THE JOB

• Clean drafting-board layout that stays readable on site

• Works fully offline — no account and no internet needed

• Switch instantly between protractor and inclinometer modes

• Optional haptic feedback when you reach common angles

ABOUT ACCURACY

The inclinometer reads your phone's built-in accelerometer, so what you get is as good as that sensor and how flat the phone sits. Use the zero function against a reference surface before an important reading. This is a practical angle measure app for school, workshop and home projects — it is not a calibrated metrology instrument and should not be used where a certified measurement is required.

PRO UPGRADE

Unlock Pro to measure angles directly on an imported photo, save and label your measurements, freeze and hold the live reading, and remove ads.

Whether you are a student learning geometry, a carpenter checking a miter, a DIYer hanging a shelf, or a photographer levelling a shot, this digital protractor gives you an angle in seconds.

PRO SUBSCRIPTION

The core tools stay available without paying. Pro starts with a 7-day free trial, and ads keep showing during that trial. After it ends, the weekly subscription renews automatically and removes the ads. Cancel any time in Google Play.

If you already bought the Pro version, it stays yours for life, with no subscription.

DIGITAL PROTRACTOR FOR SCHOOL AND GEOMETRY

A physical protractor is difficult to hold steady on paper while reading the angle. This digital protractor holds its position: drag the two arms to the lines you are measuring and read the angle precisely. Works for geometry homework, technical drawing, and any school problem that requires measuring an angle from a diagram on a screen or on printed paper photographed with the phone.

ANGLE FINDER FOR CARPENTRY AND DIY

The inclinometer mode uses the phone's accelerometer to read the tilt of whatever surface it is resting on. Hold the phone flat against a wall stud to check plumb, against a shelf bracket to confirm the angle, against a miter cut to verify it before you reach for the saw. The zero-to-surface function lets you measure relative angles — rest the phone on a reference surface, zero it, then measure a second surface to get the angle between them.

SLOPE PERCENTAGE AND ROOF PITCH

Slope percentage is the standard for drainage and accessibility ramps (a 1:20 ramp = 5 % slope). Roof pitch is measured in rise-over-run (4/12, 6/12). This angle finder shows both the degree reading and the slope percentage so you can match whatever format your building standard or job sheet uses. A 4/12 roof pitch is 18.4°; a 1:20 accessibility ramp slope is 2.9° — the app shows both so you can cross-check.

STAIRCASE ANGLE AND STRINGER PITCH

A staircase stringer angle is typically 30° to 40°, with 37° being a common comfortable pitch. Place the phone against the stringer board to read the angle in degrees, then cross-check it against the slope percentage (73–84% for that range). The angle finder mode gives you the degree reading; the inclinometer mode reads the angle of the physical surface in real time.