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Inches to CM converter

Convert inches to centimeters instantly (and back) with the exact 2.54 definition — TV sizes, US product specs, and sewing measurements in metric.

1 in = 2.54 cm

1 in = 2.54 cm · multiply by 2.54

Conversions run instantly on your device — nothing is sent anywhere.

Maintained by ToolsNexus

Convert inches to centimeters — and back — using the exact definition (1 in = 2.54 cm). Loads with in → cm preselected: built for reading US product specs, patterns, and print sizes in metric. (Going the other way — a cm measurement you need in inches — the cm to inches converter starts reversed and has the height chart.)

The formula

cm = inches × 2.54 · inches = cm ÷ 2.54. Mental math: multiply by 2.5 and add 1.6% — or just remember 4 in ≈ 10 cm and scale.

Common values

inches cm inches cm
0.25 0.635 12 30.48
0.625 1.588 24 60.96
1 2.54 27 68.58
4 10.16 36 91.44
6 15.24 55 139.70
8.5 21.59 65 165.10

Screens, paper, patterns

Screens carry inch names everywhere — the table has the monitor and TV diagonals. Paper and prints: US Letter vs A4 is a 6 mm ambush for international documents (see FAQ), and photo frames worldwide still sell as 4×6, 5×7, 8×10. Sewing and crafts: US patterns are inch-built; the 5/8-inch seam allowance is 1.59 cm. Fine hardware sizes below an inch read better in millimeters — that’s the mm to inches converter, which also handles fractions like 3/8″.

Private by design

The math runs on your device as you type — nothing is uploaded or logged. Six categories, 46 units: the unit converter.

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Frequently asked questions

What is the exact inches to cm formula?
Multiply inches by 2.54 — exact since the 1959 international agreement defined the inch as precisely 25.4 mm. So 12 in = 30.48 cm, no rounding involved. Reverse: cm ÷ 2.54.
How big is a 55-inch TV in centimeters?
The 55″ is the diagonal: 139.7 cm. A 65″ TV is 165.1 cm diagonal, roughly 144 × 81 cm of screen at 16:9. For will-it-fit questions, convert the stand width from the spec sheet, not the diagonal.
What are common US paper and frame sizes in cm?
US Letter is 8.5 × 11 in = 21.59 × 27.94 cm (close to but not A4′s 21 × 29.7). Photo prints: 4×6 in = 10.2 × 15.2 cm, 5×7 = 12.7 × 17.8 cm, 8×10 = 20.3 × 25.4 cm — the sizes metric-country frame shops still sell by their inch names.
How do sewing and yarn measurements convert?
US patterns quote seam allowances and hems in inches: 5/8 in = 1.59 cm (the standard seam), 1/4 in = 6.4 mm (quilting). Knitting gauge of "stitches per 4 inches" is per 10.16 cm — metric patterns use a flat 10 cm square, so recount rather than convert if tension matters.

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