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.
Calibrate to your screen with a standard card, then measure small, flat objects in millimeters or inches. No camera, account, or subscription.
- One free measurement
- 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
Calibrate with the 53.98 mm short edge of a standard bank or ID card. The card is never scanned or photographed.
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.
The app asks for a real-world reference before it treats screen pixels as physical distance.
- 1
Calibrate
Match the card
Place a rigid standard card flat on the screen and match the brackets to its 53.98 mm short edge. - 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.
Complete one measurement at no charge. If the tool fits your workflow, unlock unlimited measurements with a one-time in-app purchase. Apple shows the current local price before you buy.
- One full completed measurement is free
- Unlimited ruler and caliper measurements after unlock
- Restore your purchase with the same Apple Account
App Store release in progress
The download link will appear here as soon as the listing is live.
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.