Online Ruler — Inches
A real 12-inch ruler on your screen. 1/16" precision on the inch scale. Drag to measure any span. Calibrate for your monitor.
Place a physical credit card on your screen. Drag the slider until the dashed box matches the card exactly, then click Apply.
Reference Objects at Actual Size
Hold the real object against the screen to verify calibration.
How to Use This Inch Ruler
Place an object on your screen with one edge at the 0 mark. Read where the other edge falls on the inch scale. The top edge shows inches with marks for every 1/16". The bottom edge shows centimeters for quick metric reference.
For precise measurements, click Calibrate and use a credit card. The card is exactly 3.370 inches wide — drag the slider until the dashed box matches the card. Your calibration saves automatically.
Frequently Asked Questions
Is this an actual size inch ruler?
Yes — when calibrated. By default it uses 96 PPI (the web standard), accurate on most desktop monitors. Click "Calibrate" and use a credit card to match your screen's exact PPI for maximum accuracy.
How do I use an online ruler in inches?
Place an object on your screen and align one edge with the 0 mark. Read where the other edge falls. The top scale shows inches in 1/16" precision. Drag on the ruler to highlight any span and see the measurement.
How many inches is a ruler?
A standard ruler is 12 inches (30.48 cm) long. This online ruler is also 12 inches — one full foot.
How do I read an inch ruler?
The numbered marks are whole inches. Each inch is divided by smaller ticks: the longest sub-tick is the half inch (1/2"), then quarter inch (1/4"), eighth inch (1/8"), and the smallest tick is a sixteenth inch (1/16").
What is 1/16 of an inch?
1/16 inch = 1.5875 mm = 0.0625 inches. This ruler shows 1/16" marks — the smallest ticks between each inch. It's the standard precision for US inch rulers.
How accurate is this online ruler?
At the default 96 PPI, it's accurate for most desktop monitors. Calibrate with a credit card for precise measurements accurate to within 0.5 mm. The calibration is saved between visits.