RulerApp: Ruler & Tape Measure

RulerApp turns your iPhone or iPad screen into a true-size ruler. Lay an object on the screen and read its length in cm or inches. Match the size once with a standard card ("Match Size") for more accurate marks.

Beyond the screen, it is a pocket toolbox: a "Long (slide along)" mode for items longer than the screen, AR measuring with the camera, a ring size finder, a protractor, a spirit level, a plumb line and a decibel meter.

TRUE-SIZE RULER
- On-screen ruler at true scale (cm/inch, marked in 1mm or 1/16-inch steps)
- Built-in screen sizes for each iPhone and iPad model, so the marks are right even before you match the size with a card; unknown models are guided to "Match Size" first
- "Match Size": hold a standard credit card (85.6mm) to the outline and match the size quickly, in either orientation
- Drag start/end markers to calculate the distance between two points
- Fine-tune markers in 0.1mm steps with the − / + buttons, and snap them to tick marks for small parts like screws and beads
- Each result shows an accuracy estimate (for example ±0.3mm when "Matched with a card")
- Works in portrait and landscape (landscape measures farther)

LONGER THAN THE SCREEN
- "Long (slide along)" mode: mark the end of the screen, slide your device along the object, and the ruler continues from the previous length to give the total
- Print a paper ruler with AirPrint and use it without your device

AR MEASURE WITH THE CAMERA
- Measure walls, desks and objects too big or too far away for the screen
- Area of rectangles, volume of boxes, diameter and area of circles
- Angles between two lines, height from the floor, and the total length of a multi-segment path
- Export what you measured as a floor plan image or PDF with dimensions

MORE TOOLS
- Ring size finder: place a ring you own on the screen, match the inner circle, and see its US, UK, EU and Japanese sizes with the inner diameter in mm
- Photo measure: write the sizes you measured on a photo and share it as one image, for example for a marketplace listing
- Protractor: read the angle of an object or drawing placed on the screen
- Spirit level: check whether a surface is flat or plumb
- Plumb line: a line that always points straight down, with the angle off vertical
- Decibel meter: current and maximum sound level (dB estimate) using the microphone
- Altimeter: air pressure, relative height change, elevation and coordinates
- See online sizes at true scale: share text like "8.6 × 5.4 cm" from Safari to show a rectangle of that size on screen, or type the size yourself
- Unit converter for cm / inch / mm, plus day-of-year (Julian date) conversion

QUICK TO OPEN
Open the ruler in one step from Home Screen and Lock Screen widgets, a Control Center button, the Action button, Siri or Shortcuts.

YOUR MEASUREMENTS
- Save favorite measurements and recall them instantly
- A counter shows how many measurements you saved today, this week and in total. Deleting a saved measurement lowers the count.
- Blueprint dark theme: subtle grid lines on a deep blue background


Measurements are processed on your device. The microphone is used only to show the sound level; audio is not recorded or saved.
After your first measurement, the app may ask once for a rating (within Apple's limits).

FREE AND FULL ACCESS
Free (with banner ads): the true-size ruler, Match Size, the "Long (slide along)" mode, fine-tuning, protractor, spirit level, plumb line, decibel meter, altimeter, printable ruler, online sizes, unit converter, widgets and Siri, and up to 3 saved measurements.
Full Access (one-time purchase, no subscription): ring size finder, AR measure, photo measure, unlimited saved measurements with export, and no ads. Customers who previously bought the paid app keep using it without ads.

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Support: https://smallappworks.com/rulerapp/support/