Common questions

Yes. Open ruleronphone in your mobile browser, calibrate against a card or known length, keep zoom near 100%, then measure with edge ticks, Select, or Guides. Hide Info for a full measuring canvas.

Yes. This site is a free online / digital ruler that runs in the browser - no install required. It works as a ruler online in cm or inches after calibration.

Calibrate first, switch the primary unit to inches, then align a trusted 1 inch mark (on a physical ruler or marked object) with the on-screen ticks and fine-tune with +/- if needed.

Calibrate, choose cm (or mm), place the object against the screen edge or use Select to read width/height in centimeters. That is the same workflow as an online ruler in cm.

A smartphone can measure physical objects when the on-screen scale is calibrated to that display. ruleronphone stores calibration locally so the same phone stays consistent between visits.

ruleronphone measures on the screen surface itself rather than through the camera. Place the object on or against the glass for actual-size ticks - private and independent of AR camera permissions.

Yes. Use this page as an online measuring tape style tool for short lengths: calibrate, pick units, and read ticks or selection dimensions. For long distances a physical tape is still better.

Major ticks follow your selected unit (mm, cm, or inches). After calibration, tick spacing matches real-world size on your display. Use the secondary unit readout when you need both metric and imperial.

Tap Calibrate (card, A4/Letter, custom, device, or diagonal), set units and edges, optionally take the short tour, then Hide Info and measure. Use Select for W/H/Diag/Area and paired Guides for spacing.

After calibration against a known physical object, short-distance accuracy is typically within a fraction of a millimeter - if browser zoom is ~100% and the OS is not applying unusual display scaling.

ID-1 cards are 85.60 x 53.98 mm worldwide. A4 and Letter sheets are also reliable references. Custom length and diagonal are available when you do not have those objects.

Yes. Browser zoom changes how CSS pixels map to physical size. ruleronphone watches for zoom changes and shows a warning when you are not near 100%.

No. Calibration, theme, edge placement, and preferences stay in browser localStorage only. Measurements never leave your device.

Yes. Calibrate on the same device you measure with - Samsung, other Android phones, iPhone, tablets, and desktops. Recalibrate if you switch devices or displays.