Two focused tools
Use a movable ruler origin and end marker, or align two digital-caliper jaws around an object.
Calibrated on-screen measurement
A ruler and digital caliper, right on your iPhone.
Measure small, flat objects in millimeters or inches, and check the screen scale against a known reference. No camera, account, or subscription.
- Calibrated for your screen
- One-time lifetime unlock
- Works offline after calibration
2measurement modes
4unit formats
0subscriptions
Purpose-built, not overloaded
Small-object measurement without the toolbox clutter.
Everything is shaped around one job: placing a small object on the screen edge and getting a clear, adjustable reading.
Four useful formats
Switch between millimeters, centimeters, decimal inches, and fractional inches without changing the measured distance.
Matched to your screen
Follow the scale check shown in your app version. Compare important results with a known physical ruler. No camera is used.
Private by design
Measurements stay on your iPhone. There is no account, advertising, tracking, or developer measurement server.
The instrument, in your hand
Built to make the contact points obvious.
Large controls, clear markers, and a high-contrast readout keep the measurement surface legible while you align an object.
From setup to result
Three deliberate steps.
Follow the setup shown in your app version. Verify important measurements with a physical ruler before relying on the result.
- 1
Calibrate
Check the screen scale
Follow the in-app setup and match the exact reference length it displays. Do not substitute a different length. - 2
Align
Set the object
Keep a small, flat object along the usable screen edge and move the ruler markers or caliper jaws to its edges. - 3
Read
Fine-tune the result
Nudge the controls when needed, lock the current orientation, and read the result in your preferred unit.
One distance, your format
Metric. Decimal. Fractional.
Change how a result is displayed without moving the markers or changing the underlying measurement.
12.7 mm1.27 cm0.50 in1/2 in
Private by design
Your measurements stay on your iPhone.
Measurement and calibration data are not sent to us. The app has no account, advertising, tracking, camera access, or developer measurement server. Limited privacy-conscious analytics contain product events, never measured values.
Lifetime access
One purchase. No subscription.
Unlock unlimited measurements with a one-time in-app purchase. Some new users receive a first measurement at no charge; others see the lifetime offer after the introduction. The app shows your available access and Apple shows the local price before you buy.
- No recurring payments
- Unlimited ruler and caliper measurements after unlock
- Restore your purchase with the same Apple Account
Available on the App Store
A practical tool, used with judgment.
Ruler & Caliper is not a certified measuring instrument. Results depend on calibration, alignment, screen configuration, and the object being measured. Verify important measurements with a suitable physical reference.