Ruler & Digital Caliper
On-screen ruler and caliper, pay once
This app turns the iPhone screen into a ruler with a movable origin and end marker, plus a digital caliper with two independently adjustable jaws. Calibration uses the 53.98 mm short edge of a standard bank or ID card placed flat on the screen and aligned with brackets; the card is never scanned or photographed. Four unit formats are available: millimeters, centimeters, decimal inches and fractional inches to 1/64.
It is meant for small, flat objects. The developer states plainly that results depend on calibration, alignment, display settings, cases and screen protectors, and that this is not a certified measuring instrument. Recalibrate after changing iPhone or Display Zoom. Calibration and preferences are stored locally, and no account is required.
Why no subscription? Full access comes from a one-time “Lifetime Access” purchase of $9.99; the download itself is free with that in-app purchase.
Keywords: ruler · caliper · measuring · calibration · utility · no subscription · one-time purchase · iPhone
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