Convert mm to inches
PrintMillimeter to Inch Conversion Table
| Millimeter (mm) | Inch (in) |
|---|---|
| 0.01 mm | 0.0003937008 in |
| 0.1 mm | 0.0039370079 in |
| 1 mm | 0.0393700787 in |
| 2 mm | 0.0787401575 in |
| 3 mm | 0.1181102362 in |
| 5 mm | 0.1968503937 in |
| 10 mm | 0.3937007874 in |
| 20 mm | 0.7874015748 in |
| 50 mm | 1.968503937 in |
| 100 mm | 3.937007874 in |
| 1000 mm | 39.37007874 in |
Converting inches (in / “) to millimeters (mm) is one of the most frequent dimensional calculations in engineering CAD drafting, 3D printing, woodworking, CNC machining, hardware fasteners (screws and bolts), display screen sizing, and architectural blueprints.
Our free online Inches to mm Converter provides instant high-precision length conversions:
- Decimal Inches to Millimeters: Multiply inches by
25.4(exact definition). - Fractional Inches to Millimeters: Convert fractional inches (e.g.
1/8",3/16",5/16",7/8") to exact mm. - Millimeters to Inches: Multiply mm by
0.03937008(or divide by25.4).
How to Convert Inches to Millimeters (in to mm Formula)
Under the 1959 International Yard and Pound Agreement, 1 international inch is standardized as exactly 25.4 millimeters. The mathematical formula is:
Length in Millimeters (mm) = Length in Inches (in) × 25.4
Converting Fractional Inches to Decimal and Millimeters
To convert a fractional inch measurement (such as 3/8" or 1 1/4") to millimeters:
- Divide the numerator by the denominator:
3 ÷ 8 = 0.375 inches. - Multiply by 25.4:
0.375 × 25.4 = 9.525 mm.
Fractional Inch to Millimeter Machining Reference Chart (1/64″ to 1″)
Below is the standard engineering and machinist lookup table converting fractional inches to decimal values and exact millimeters:
| Fractional Inch (in) | Decimal Inch | Exact Millimeters (mm) | Standard Hardware Benchmark |
|---|---|---|---|
| 1/64″ | 0.0156 in | 0.3969 mm | Precision wire gauge |
| 1/32″ | 0.0313 in | 0.7938 mm | Sheet metal gauge |
| 1/16″ | 0.0625 in | 1.5875 mm | M1.6 micro screw diameter |
| 1/8″ | 0.1250 in | 3.1750 mm | 1/8″ drill bit / M3 screw |
| 3/16″ | 0.1875 in | 4.7625 mm | 3/16″ tubing / M5 bolt |
| 1/4″ | 0.2500 in | 6.3500 mm | 1/4″ hex drive bit / M6 bolt |
| 5/16″ | 0.3125 in | 7.9375 mm | 5/16″ automotive fitting / M8 bolt |
| 3/8″ | 0.3750 in | 9.5250 mm | 3/8″ socket drive / M10 bolt |
| 7/16″ | 0.4375 in | 11.1125 mm | 7/16″ structural fastener / M11 bolt |
| 1/2″ | 0.5000 in | 12.7000 mm | 1/2″ copper pipe / socket drive |
| 9/16″ | 0.5625 in | 14.2875 mm | 9/16″ wrench size / M14 bolt |
| 5/8″ | 0.6250 in | 15.8750 mm | 5/8″ garden hose connector / M16 |
| 11/16″ | 0.6875 in | 17.4625 mm | 11/16″ heavy structural bolt |
| 3/4″ | 0.7500 in | 19.0500 mm | 3/4″ plumbing conduit / M20 bolt |
| 13/16″ | 0.8125 in | 20.6375 mm | 13/16″ spark plug socket |
| 7/8″ | 0.8750 in | 22.2250 mm | 7/8″ motorcycle handlebar diameter |
| 15/16″ | 0.9375 in | 23.8125 mm | 15/16″ industrial socket |
| 1″ | 1.0000 in | 25.4000 mm | 1.000 Inch Exact International Base Standard |
Common Diagonal & Display Size Conversions (Inches to mm / cm)
| Inches (“) | Millimeters (mm) | Centimeters (cm) | Common Application |
|---|---|---|---|
| 2 inches | 50.8 mm | 5.08 cm | 2″ Photo print / small coaster |
| 6.1 inches | 154.94 mm | 15.49 cm | Standard smartphone display diagonal |
| 8.5 × 11 inches | 215.9 × 279.4 mm | 21.59 × 27.94 cm | Standard US Letter document paper |
| 13.3 inches | 337.82 mm | 33.78 cm | Compact laptop display |
| 15.6 inches | 396.24 mm | 39.62 cm | Standard full-size laptop screen |
| 24 inches | 609.6 mm | 60.96 cm | Desktop computer monitor |
| 27 inches | 685.8 mm | 68.58 cm | High-resolution desktop monitor |
| 55 inches | 1,397.0 mm | 139.70 cm | Living room 4K television |
| 65 inches | 1,651.0 mm | 165.10 cm | Large format 4K display |
Related Length & Distance Calculators
Need to convert other distance units or calculate metric scaling? Explore our related tools:
- cm to Inches Converter — Convert Centimeters to Decimal & Fractional Inches.
- Feet to Meters Converter — Convert feet (ft) to meters (m).
- Master Conversion Calculator — Universal conversion calculator across all physical categories.
Frequently Asked Questions (FAQ)
How many mm is 1 inch?
1 inch is equal to exactly 25.4 millimeters.
How do you convert 1/4 inch to mm?
Divide 1 by 4 (0.25) and multiply by 25.4: 0.25 × 25.4 = 6.35 mm.
How many mm is 3/4 inch?
3/4 inch equals 0.75 × 25.4 = 19.05 mm.
Is 1 mm equal to 0.1 cm?
Yes. 1 millimeter (mm) is equal to 0.1 centimeters (cm) and 0.001 meters (m).