A clear guide to measuring.

01 · Measure length with two cursors

Align the object with the scale at the screen edge, then mark its endpoints with the two cursors. The reading shows the distance between them.

1. Choose Length at the top of the app.
2. Drag the orange and blue cursors to the two endpoints of your object.
3. Use the minus and plus controls for A and B to adjust in 0.1 mm steps.
4. Lock the measurement once aligned. Unlock it when you need to adjust again.

02 · Align two edges and read the angle

The protractor has two independently movable edges, A and B. Orange and blue distinguish the edges; the highlighted area represents the angle currently displayed.

1. Choose Angle at the top of the app.
2. Drag the center cross to position the vertex.
3. Drag handles A and B to align each edge with your reference object.
4. Drag the graduated ring to rotate both edges together while keeping their angle.
5. Switch between the smaller angle and reflex angle to read the side you need.

03 · Fine-tune, enter or choose an angle

Use small adjustments when dragging is inconvenient. For a particular angle, enter its value or choose a common preset.

1. The minus and plus controls for A and B rotate that edge counterclockwise or clockwise in 0.1° steps.
2. Tap the pencil beside the reading to enter an angle or choose a preset such as 30°, 45°, 60° or 90°.
3. Smaller-angle mode accepts 0°–180°; reflex mode accepts 180°–360°. Values are rounded to the nearest 0.1°.
4. Choose Apply, then rotate the ring to align both edges together. Cancel keeps the previous angle.

04 · Check and calibrate the length scale

Length conversion relies on your device’s screen information. Use a reliable physical ruler to check the scale on first use or whenever it seems incorrect.

1. Choose Length and open calibration.
2. Align the zero marks of the physical and screen rulers. Compare the longest visible span you can.
3. Adjust the calibration slider until the scales agree, then check several marks in between.
4. Choose Done to save. Cancel discards this calibration edit.

05 · Lock, rotate the device and switch tools

Lock prevents accidental touches from changing your measurement. The protractor keeps its angle when the device rotates. Length and Angle retain their separate states during the same app session.

1. Lock the measurement to hold it steady. Unlock before adjusting it.
2. Tap blank space to hide or show the controls.
3. After a change in orientation or screen size, check that the object and measuring edges are still aligned. Length cursors may need repositioning.

06 · Understand the screen’s limits

EasyRuler is for small flat objects that fit on the screen, or for use as an on-screen angle reference. The screen is opaque: it cannot reveal a drawing below it or extend into a physical ruler beyond its own size.

07 · Purchase, offline use and language

EasyRuler is a one-time App Store purchase with no ads, subscriptions or accounts. Measurement and calibration work offline. Apple handles purchase and download; see the listing for the current version, price and compatible devices.

1. To download again, use the Apple Account that purchased the app and find it in your App Store purchases.
2. In the app, choose More → Settings → 语言 / Language to open system settings and change the app language.
3. Opening support email or the privacy policy uses the corresponding mail or network service.