How to Measure Without a Ruler

You don’t need a ruler to measure something accurately. Many everyday objects are made to exact, standard sizes, and you probably have several of them in your wallet or on your desk.

Objects with exact sizes

Object	Size in inches	Size in mm
US dollar bill (any bill)	6.14 × 2.61	156 × 66.3
Credit or debit card	3.370 × 2.125	85.60 × 53.98
US Letter paper	8.5 × 11	215.9 × 279.4
A4 paper	8.27 × 11.69	210 × 297
US quarter (diameter)	0.955	24.26
US nickel (diameter)	0.835	21.21
US penny (diameter)	0.750	19.05
US dime (diameter)	0.705	17.91

1. Use a dollar bill

A bill is just over 6 inches long. Fold it in half across its length for about 3 inches (3.07 in), or fold it in half again for about 1.5 inches. It’s the best everyday option for measuring things a few inches long.

2. Use a credit card

A card’s long side is 3 3/8 inches (3.37 in) and its short side is 2 1/8 inches (2.125 in). The same size applies to debit cards, most ID cards and many gift cards.

3. Use coins

Coins are handy for small things. Four pennies in a row measure 3 inches exactly (4 × 0.75 in). A quarter is just under 1 inch across.

4. Use printer paper

A sheet of US Letter paper is 8.5 × 11 inches. Fold it in half lengthwise for 4.25 inches, or across for 5.5 inches. Outside North America, A4 paper is 210 × 297 mm, which makes it good for centimeters.

5. Use your phone or computer screen

Our online ruler turns your screen into a real-size ruler. For the most accurate result, calibrate it in the actual size viewer by matching a real coin, bill or card to the shape on screen.

6. Print a ruler

If you have a printer, the printable ruler gives you a paper 12-inch ruler and a 30 cm ruler. Print at 100% and check the 1-inch square first.

7. Use your hand (rough estimates only)

Body measurements vary a lot from person to person, but once you know yours, they’re useful for quick estimates:

• Top joint of your thumb: roughly 1 inch for many adults
• Hand span (thumb tip to little finger tip, spread wide): roughly 7–9 inches
• Your stride: roughly 2–2.5 feet

Measure your own hand once against a real ruler and remember the numbers.

8. Use a string and compare later

For curved or long objects, wrap or stretch a piece of string or a paper strip along them, mark the length, and measure the string later against any of the objects above.

Tip: Longer reference objects give more accurate results. Measuring 6 inches with a dollar bill is more precise than adding up six quarters.