Sometimes you need a measurement and the tape is in another room. Ruler apps solve that by drawing a scale on your screen, and we wanted the same thing without an install, so we built Palm Gauge. It is a true-size ruler in centimetres and inches, a two-handle measuring tool, an angle gauge, and a small daily game that trains your eye. Free, no download, no signup, and it runs right here.
Use Palm Gauge now
Drag the A and B handles to measure the length between them. For a true-size scale, spend thirty seconds on the Calibrate tab first.
How to use it
On the Scale tab, drag the A and B handles, or focus one and press the arrow keys (Shift moves in bigger steps). The readout shows the distance in millimetres, centimetres, decimal inches and the nearest sixteenth of an inch. Switch to vertical for a taller view, and turn on snapping to land on whole millimetres or 1/16 inch marks.
The Angle tab is a protractor with two arms that you drag, and it works without calibration. The Estimate tab is the daily challenge: five familiar objects, one guess each by dragging a slider, scored by how far off you are. When you finish the set, Share sends your score to this page. Your calibration, streak and best score stay in your browser, and nothing leaves your device.
Why calibration matters
A web page cannot read your screen’s physical size, so any browser ruler is a guess until you check it. Palm Gauge starts with the size your browser reports, which is often close on a desktop and less certain on phones. On the Calibrate tab you hold a bank card (85.60 mm wide) against the bar and drag the slider until the edges line up.
Done carefully, that usually gets you within a millimetre or two. It is not a substitute for a tape measure when a fit matters, such as furniture or a part that has to slot into something. The calibration is stored per device, and it adjusts if you change your browser zoom.
How it compares to Ruler
The Ruler app on Android turns your phone into a measuring scale, and the idea is the same: a ruler on your screen, ready in seconds. Palm Gauge keeps that core, with cm and inch scales, a measuring tool and a calibration step, and it needs nothing but a browser. It also works on a laptop or desktop screen, which a phone app does not.
What it leaves out is everything that depends on the phone itself. There is no camera measuring, no saved measurements and no sensors, because a browser page cannot offer those reliably. The visible length is limited to your screen, so a phone shows only a few centimetres at a time.
On top of the basics we added the Estimate challenge, which gives the tool some replay value, and an angle gauge. If you measure regularly, the installed app is the better home for it.
Get the full app
Ruler is available for Android. If you want a measuring tool that lives on your phone, you can find it at the stores below.
Frequently asked questions
How accurate is an on-screen ruler?
It is only as accurate as its calibration. Browsers cannot know a screen’s physical dimensions, so Palm Gauge asks you to match a bank card to a bar once. After that it is typically within a millimetre or two, and you can check it any time by laying a card or a coin against the scale.
Is this the real Ruler app?
No. Palm Gauge is an original tool we built, inspired by on-screen ruler apps like Ruler. It is not affiliated with, endorsed by, or connected to the app’s publisher. The download links above point to the official listings.
Can it measure in both cm and inches?
Yes. The scale shows millimetre ticks on one edge and 1/16 inch ticks on the other, and the readout gives millimetres, centimetres, inches and the nearest sixteenth.
Is it free?
Completely. No ads, no account and no tracking. Your calibration and scores live in your browser’s local storage.
Does it work offline?
Once the page has loaded, the tool makes no further network requests, so it keeps working if your connection drops.
