HomeBlogBlogDouble-Scale Tape: Read Inches & Centimeters Right

Double-Scale Tape: Read Inches & Centimeters Right

What does double scale mean on a measuring tape, and how do I read inches and centimeters correctly?

A “double scale” measuring tape shows two measurement systems on the same tape—usually inches on one edge and centimeters (metric) on the other. This lets you measure once and record the result in either system without converting. Double-scale tapes are common on sewing tapes, flexible rulers, and compact measuring tapes used for crafts, tailoring, and everyday measuring.

How to read inches correctly

The inch side is divided into large numbered marks (1, 2, 3, etc.) and smaller ticks between them. Each inch is typically split into fractions like 1/2, 1/4, 1/8, and sometimes 1/16. The longest tick is usually the full inch mark; medium ticks often indicate halves and quarters; the shortest ticks are the smallest fractions.

To read inches, line up the tape’s “0” with the starting edge of what you’re measuring, then find the last whole inch number before the end point. Next, count the fraction ticks past that number. For example, if the end point lands two 1/8 marks past 5 inches, that’s 5 2/8 inches, which simplifies to 5 1/4 inches.

How to read centimeters correctly

The metric side is simpler: centimeters are numbered (1, 2, 3, etc.), and each centimeter is divided into 10 millimeters. The shorter ticks between centimeter numbers represent millimeters; the middle-length tick often marks 5 mm (half a centimeter).

To read centimeters, align “0” to the start, find the nearest centimeter number, then add the millimeters to get a precise measurement. For example, 12 cm plus 3 mm equals 12.3 cm (or 123 mm).

Quick tips to avoid mistakes

Make sure you’re reading the correct edge (inch vs. cm), start at the true “0” mark (not the tape’s physical end if it has a margin), and keep the tape flat and snug. For a practical example using a double-scale flexible tape, see this double-scale tape guide.