Inches to Centimeters
Convert inches to centimeters with the exact factor 1 inch = 2.54 cm. Enter any inch value — get centimeters for product dimensions, clothing, and international specifications.
Enter your values above to see the results.
Tips & Notes
- ✓The conversion factor 2.54 cm/inch is exact by international definition since 1959 — there is no rounding involved. 1 inch = 2.54 cm = 25.4 mm = 0.0254 m, all exact.
- ✓Quick estimates: 1 inch ≈ 2.5 cm (2% error); 4 inches ≈ 10 cm; 12 inches (1 foot) ≈ 30 cm (exact: 30.48 cm). For rough mental math, the 4 inches ≈ 10 cm approximation is very useful.
- ✓Screen and display sizes are quoted in diagonal inches worldwide. A 27-inch monitor = 27 × 2.54 = 68.58 cm diagonal. A 6.1-inch smartphone screen = 6.1 × 2.54 = 15.49 cm diagonal.
- ✓US lumber dimensions use nominal inches that differ from actual: "2×4" lumber is actually 1.5 × 3.5 inches (3.81 × 8.89 cm). Always use actual dimensions for calculations, not nominal sizes.
- ✓Paper sizes: US Letter (8.5 × 11 inches) = 21.59 × 27.94 cm. Compare to A4 (21 × 29.7 cm) — similar width, A4 is slightly taller. Legal paper (8.5 × 14 inches) = 21.59 × 35.56 cm.
Common Mistakes
- ✗Multiplying by 2.5 instead of 2.54 — using 2.5 introduces a 1.6% error. For most casual conversions this is fine, but for manufacturing, design, or medical contexts, always use the exact 2.54.
- ✗Confusing millimeters and centimeters — 1 inch = 25.4 mm = 2.54 cm. If your result seems 10× too large, you may have used the mm factor (25.4) but labeled the result as cm.
- ✗Mixing fractions and decimals for inch measurements — US measurements often use fractions (3/8 inch, 5/16 inch). Convert to decimal first: 3/8 = 0.375 inches = 0.375 × 2.54 = 0.9525 cm.
- ✗Applying the inches-to-cm factor in the wrong direction — to convert cm to inches, divide by 2.54 (not multiply). Multiplying cm by 2.54 gives a result even larger than the cm value.
- ✗Not accounting for nominal vs. actual dimensions in US construction — pipe sizes, lumber, and some hardware use nominal inch designations that do not equal actual measurements. Verify actual dimensions before converting.
Inches to Centimeters Overview
The inch is the standard measurement for US products, construction, and body dimensions — but the world beyond the US operates in centimeters. The conversion is exact: 1 inch = 2.54 cm by international definition, requiring no approximation.
Inches to centimeters formula:
cm = inches × 2.54 | 1 inch = 2.54 cm (exact, defined 1959)
EX: A 24-inch monitor diagonal → 24 × 2.54 = 60.96 cm. US Letter paper 8.5 × 11 inches → 8.5 × 2.54 = 21.59 cm wide, 11 × 2.54 = 27.94 cm tallInverse — centimeters to inches:
inches = cm ÷ 2.54 | or inches = cm × 0.3937
EX: Verify: 60.96 cm ÷ 2.54 = 24.0 inches ✓. A4 paper 21 cm wide → 21 ÷ 2.54 = 8.268 inchesCommon inch measurements in centimeters:
| Inches | Centimeters | Millimeters | Common Context |
|---|---|---|---|
| 1/4" | 0.635 cm | 6.35 mm | Small hardware, screws |
| 1/2" | 1.27 cm | 12.7 mm | Pipe, cable diameter |
| 1" | 2.54 cm | 25.4 mm | Standard reference unit |
| 2" | 5.08 cm | 50.8 mm | Lumber, tile spacing |
| 6" | 15.24 cm | 152.4 mm | Ruler half-mark, tile size |
| 12" (1 ft) | 30.48 cm | 304.8 mm | One foot |
| 18" | 45.72 cm | 457.2 mm | Countertop depth standard |
| 24" | 60.96 cm | 609.6 mm | Monitor size, tile size |
| 36" (1 yd) | 91.44 cm | 914.4 mm | One yard, door width |
| 72" | 182.88 cm | 1,828.8 mm | Standard door height (6 ft) |
| Item | Inches | Centimeters | Notes |
|---|---|---|---|
| US Letter paper | 8.5 × 11" | 21.59 × 27.94 cm | Standard US office paper |
| A4 paper (ISO) | 8.27 × 11.69" | 21.0 × 29.7 cm | International standard |
| 6.1" phone screen | 6.1" diagonal | 15.49 cm diagonal | iPhone 15 / typical flagship |
| 27" monitor | 27" diagonal | 68.58 cm diagonal | Common desktop size |
| 55" TV | 55" diagonal | 139.7 cm diagonal | Popular living room size |
Frequently Asked Questions
Exactly 2.54 centimeters. This is a defined conversion, not an approximation — since 1959, the international inch has been defined as exactly 25.4 millimeters (= 2.54 centimeters). Formula: cm = inches × 2.54. Common values: 1 inch = 2.54 cm; 2 inches = 5.08 cm; 6 inches = 15.24 cm; 12 inches (1 foot) = 30.48 cm; 36 inches (1 yard) = 91.44 cm; 72 inches (6 feet) = 182.88 cm.
Convert the fraction to a decimal first, then multiply by 2.54. Common fractions: 1/4 inch = 0.25 × 2.54 = 0.635 cm; 1/2 inch = 0.5 × 2.54 = 1.27 cm; 3/4 inch = 0.75 × 2.54 = 1.905 cm; 1/8 inch = 0.125 × 2.54 = 0.3175 cm; 3/8 inch = 0.375 × 2.54 = 0.9525 cm; 5/8 inch = 0.625 × 2.54 = 1.5875 cm. For mixed measurements like 5 and 3/4 inches: 5.75 × 2.54 = 14.605 cm.
Body measurements in inches are common in US clothing. Conversion: chest 40 inches = 40 × 2.54 = 101.6 cm; waist 32 inches = 32 × 2.54 = 81.28 cm; inseam 30 inches = 30 × 2.54 = 76.2 cm; height 5 feet 9 inches = 69 inches = 69 × 2.54 = 175.26 cm. International sizing charts typically list both inches and centimeters. For European clothing, cm measurements are standard — always verify against the specific brand chart as sizing varies.
The inch is a unit of length in the imperial and US customary systems. Since 1959, it has been defined internationally as exactly 2.54 centimeters (or 25.4 millimeters). Before 1959, the UK and US inch differed very slightly. The inch is thought to derive from the width of a human thumb, or from "uncia," the Latin for one-twelfth (of a foot). Today 12 inches = 1 foot, 36 inches = 1 yard, 63,360 inches = 1 mile. The inch is widely used in the US for everyday measurements and persists globally for screen sizes, pipe fittings, and certain engineering components.
Screen sizes are measured diagonally. Common conversions: 5 inches = 12.7 cm (small phone); 6.1 inches = 15.49 cm (standard phone); 6.7 inches = 17.02 cm (large phone); 10 inches = 25.4 cm (tablet); 13 inches = 33.02 cm (laptop); 15.6 inches = 39.62 cm (laptop); 24 inches = 60.96 cm (desktop monitor); 27 inches = 68.58 cm (desktop monitor); 32 inches = 81.28 cm (TV/large monitor); 55 inches = 139.7 cm (TV); 65 inches = 165.1 cm (TV). Note: the diagonal measurement does not directly tell you width or height without knowing the aspect ratio.
US length unit hierarchy: 1 inch (in) = 25.4 mm = 2.54 cm. 12 inches = 1 foot (ft) = 30.48 cm. 3 feet = 1 yard (yd) = 91.44 cm = 0.9144 m. 5,280 feet = 1 mile (mi) = 1,609.344 m = 1.609344 km. Smaller: 1/12 inch ≈ 1 pica (typography); 1/72 inch = 1 point (typography). Larger: 1 rod = 16.5 feet = 5.0292 m; 1 furlong = 660 feet; 1 league = 3 miles. In construction, the foot-and-inch system (5 feet 7 inches written 5′7″) is standard. To convert to cm: convert all to decimal inches first (5×12 + 7 = 67 inches), then multiply by 2.54 (= 170.18 cm).