Move mouse to see measurements
Touch screen to see measurements
Drag from ruler for guides · Double-click ruler to mark distance from 0
Open the tool above, calibrate your screen once, then hold any object against the ruler edge to measure it. The ruler works in centimeters, millimeters, and inches — switch units anytime.
Drag from the ruler edge to place sticky guide lines — just like Figma or Photoshop. Drag to reposition, click X to remove.
Show horizontal and vertical rulers simultaneously with a corner piece — measure width and height at the same time.
Auto-detect device, enter screen diagonal, or align a credit card. Fine-tune PPI to the exact pixel with ± controls.
Move your cursor anywhere on the workspace and see exact coordinates in real-time. No more guessing at measurements.
Switch to dark mode for comfortable use in low-light environments. Ruler ticks and guides adapt automatically.
Place the ruler at top, bottom, left, or right. Or mix: show both H and V rulers at any combination of edges.
Click Calibrate and choose a method. Auto-detect works for most phones and laptops. For monitors, enter your screen diagonal or hold up a credit card.
Choose top, bottom, left, or right edge using the position grid in the controls panel. Enable dual H+V rulers for two-axis measurements.
Hold or place an object against the ruler. Drag guide lines from the ruler edge to mark exact positions. The live cursor tooltip shows exact coordinates.
Switch between measurement units using the unit buttons in the control panel. Each unit is precise and immediately redraws the ruler ticks.
The default unit. Major ticks every centimeter with 10 sub-divisions down to 1mm. Ideal for everyday metric measurements and international use.
High-precision mode showing every millimeter. Perfect for small parts, jewelry sizing, electronics, and anything that needs sub-centimeter accuracy.
Shows whole inches divided into eighths. The most common unit for US measurements — use for woodworking, fabric, paper sizes, and everyday tasks.
Once you calibrate with any method, the ruler is accurate to within 1–2% for most screens. That's less than 0.5mm error on a 25mm measurement.
The credit card calibration method is the most reliable because it uses a known physical object — ISO 7810 cards are 85.60 × 53.98mm worldwide.
After calibration, use the ± buttons or arrow keys to adjust PPI in 0.5 increments. This lets you dial in accuracy beyond what any database provides.
Yes. Open this page on your phone's browser for a fully functional touch ruler. Calibrate first using auto-detect — it covers most modern iPhones and Android phones automatically.
Yes, this is one. The ruler at the top of this page works immediately without any download or sign-up. It runs on desktops, laptops, tablets, and phones.
Switch to inch mode. The large numbered ticks mark whole inches. The midpoint between any two whole numbers is half an inch. Between those you'll find quarter and eighth-inch ticks.
Click the 'cm' button in the unit selector. The ruler immediately redraws with centimeter ticks and 10 sub-divisions per centimeter for millimeter precision.
Yes. Once calibrated on your phone screen, you can place a small flat object directly against the ruler edge and read the measurement. It works for anything that fits on the screen.
Not directly — this tool is a screen ruler, not a camera-based AR ruler. For best accuracy, place your object flat against the screen and use the ruler edge to measure.
Yes. Any device with a screen and a browser can use this online ruler. After calibration, the ruler gives real-world measurements in cm, mm, or inches.
The numbered ticks mark whole units (cm, mm, or inches). Sub-ticks between them divide each unit into fractions. The longer the tick, the larger the fraction — half, quarter, and eighth marks get progressively shorter.
Without calibration, accuracy can be off by 10–50% depending on your device. After calibrating — especially with credit card calibration — accuracy is typically ±1–2%.
Browsers don't know the physical size of your screen. A CSS pixel on a 27" monitor is a different physical size than on a 5" phone. Calibration tells the ruler your screen's actual pixels-per-inch.
Credit card calibration. Every standard ISO 7810 card measures exactly 85.60 × 53.98 mm. Drag the slider until the on-screen card matches your physical card and click Apply.
Yes. Click 'mm' in the unit selector. Every major tick is 1 mm with 5 sub-divisions for 0.2 mm resolution — ideal for electronics, jewelry, and precision work.
Yes. Switch to inch mode and calibrate. On most desktop monitors, the full screen width exceeds 12 inches, giving you a complete foot ruler. Visit our 12 inch online ruler page for more.
Yes. The ruler is fully touch-enabled. On mobile, the control panel appears as a compact bottom bar. Touch the workspace to see live measurements.