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Screen Ruler
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Available in the client
This tool relies on native device capabilities and cannot run directly in a web browser. Choose one of the supported clients below to continue.
After opening the client, search for “Screen Ruler” to start.
View centimeter and millimeter scales full screen, drag the measuring line to read values, and calibrate the screen ratio with a standard bank card.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
This on-screen ruler draws centimeter and inch marks so you can compare a small object directly with your display. It begins from a 96-DPI reference scale, which is a CSS layout convention rather than a guarantee that an inch on the screen is physically one inch. The actual display density, operating-system scaling, browser zoom, and monitor can change the physical size.
Calibrate with a known reference object placed against the screen. Available choices include a bank card, a US quarter, and a 1-yuan coin. Adjust the on-screen reference bar until it matches the physical object's measured width or diameter, then confirm. The ruler recalculates its scale from that match. Reset returns to the default estimate. The selected scale is saved in the browser for a later visit.
Centimeter mode marks each centimeter with ten millimeter subdivisions. Inch mode marks each inch with sixteenths. A medium-length tick marks the halfway point. The page provides a visible linear scale; it does not measure a photo, a remote object, or a distance that is not placed alongside the display.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Choose one of the displayed reference objects and hold a matching physical item against the screen. A bank card or quarter is convenient in the United States; use the exact object type selected.
Move the slider until the colored bar spans the reference item's known dimension as closely as you can judge. Confirm to apply the calibration, or cancel to leave the current scale unchanged.
Switch between centimeters and inches, then place the object edge at the ruler's zero point. Read the major mark and the shorter subdivisions together.
Changing browser zoom, display scaling, window/display, or monitor can change the physical scale. Repeat the physical match after such a change; reset restores the default estimate.
Use cases
See how the tool fits into real work and everyday tasks.
Place a screw, connector, or paper sample against the display after calibration to estimate its length. For a fit-critical component, confirm with a physical ruler or caliper.
Use the scale to inspect a short printed line or mark while the paper is held flat against the screen. This is a quick visual check, not a substitute for a controlled print measurement.
Switch units to show how a centimeter divides into millimeters and an inch into sixteenths. The major and intermediate ticks make a simple measurement lesson easier to follow.
Q&A
Find concise answers to common questions and confusing cases.
Only as a screen-drawn reference. The initial 96-DPI scale follows a CSS convention and may not match physical inches or centimeters on your display. Calibrate against an object for physical measurements.
Browser zoom, operating-system display scaling, or using a different monitor can alter the physical size of the rendered scale. Calibrate again on the current display setup.
Centimeter mode divides each centimeter into ten millimeters. Inch mode divides each inch into sixteen parts, with a distinct midpoint tick.
No. It displays a scale on the screen for an object placed next to it. It does not analyze images or infer dimensions from perspective.
Notes
Review scope, result limitations, and important precautions before use.
Calibration depends on aligning a known object and on keeping the display configuration stable. Small alignment errors, screen scaling changes, or an inaccurate reference item affect the reading. Treat this ruler as a convenient estimate, not a precision instrument for machining, medical, electrical, or safety-critical decisions.
When the object is too large to rest against the display, or a tolerance matters, use an appropriate physical measuring instrument.
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