Millimetres
0
Equivalent length value
Instantly convert inches to millimetres with precise length calculations
Use our free Inches to Millimetres Converter 2026 to convert any inch value into millimetres, centimetres, metres, and feet. Includes reverse mm to inches conversion, step-by-step formula, and full reference tables.
Accurate length conversion for engineering, construction, manufacturing, and everyday use
Convert inches to millimetres using the exact formula: mm = inches × 25.4. One inch is defined internationally as exactly 25.4 millimetres — a fixed, precise conversion with no rounding error. Our tool also outputs the equivalent in centimetres, metres, and feet, giving you a complete multi-unit length breakdown in one step.
Switch seamlessly between Inches → Millimetres and Millimetres → Inches conversion modes with a single click. Whether you are reading a US blueprint in inches and need metric millimetre values, or working with metric parts that must fit imperial tooling, both directions are handled instantly from a single input value.
Essential for engineers, architects, carpenters, machinists, 3D printer users, jewellers, and students in 2026. The inch-to-millimetre conversion is one of the most common imperial-to-metric conversions used globally — particularly in countries that use both systems simultaneously, such as Australia, Canada, the UK, and the USA.
Select your conversion direction and enter a value below
The Inches to Millimetres Converter is a free online tool that converts any length in inches into the equivalent value in millimetres — and vice versa. It uses the internationally agreed exact conversion factor of 1 inch = 25.4 millimetres, established by the International Yard and Pound Agreement in 1959. This makes the inch-to-mm conversion one of the most precise unit conversions in existence, with no approximation required.
For example, a standard A4 sheet of paper is 210 mm × 297 mm — equivalent to 8.27 inches × 11.69 inches. A common M10 bolt has a 10 mm diameter, which equals 0.3937 inches. Our converter handles all these values instantly, also producing the equivalent in centimetres, metres, feet, and yards for a complete multi-unit length breakdown in 2026.
1 Inch = 25.4 Millimetres (exact) — This is a defined value, not an approximation. It was agreed internationally in 1959 and is used in all scientific, engineering, and commercial contexts worldwide. There is no rounding error in this conversion.
Converting inches to millimetres is one of the simplest unit conversions because the factor — 25.4 — is exact and defined. To convert inches to mm, multiply the inch value by 25.4. To reverse the conversion from mm to inches, divide the millimetre value by 25.4.
To convert 5 inches to millimetres using the formula:
So 5 inches = 127 mm = 12.7 cm. This is a particularly common conversion in woodworking, where a standard 5-inch board width must be specified in metric millimetres for CNC machine programming or international material ordering.
Standard conversion chain: 1 Inch = 25.4 mm = 2.54 cm = 0.0254 m. All values are exact by international definition (2026).
The reference table below shows common inches to millimetres conversions for 2026. All values use the exact conversion factor of 25.4 mm per inch. Use this quick-reference chart for engineering drawings, woodworking, manufacturing, and construction measurements.
| Inches (in) | Millimetres (mm) | Centimetres (cm) | Metres (m) | Feet (ft) |
|---|---|---|---|---|
| 0.1 inches | 2.54 mm | 0.254 cm | 0.00254 m | 0.00833 ft |
| 0.5 inches | 12.7 mm | 1.27 cm | 0.0127 m | 0.04167 ft |
| 1 inch | 25.4 mm | 2.54 cm | 0.0254 m | 0.08333 ft |
| 2 inches | 50.8 mm | 5.08 cm | 0.0508 m | 0.16667 ft |
| 3 inches | 76.2 mm | 7.62 cm | 0.0762 m | 0.25 ft |
| 4 inches | 101.6 mm | 10.16 cm | 0.1016 m | 0.33333 ft |
| 5 inches | 127 mm | 12.7 cm | 0.127 m | 0.41667 ft |
| 6 inches | 152.4 mm | 15.24 cm | 0.1524 m | 0.5 ft |
| 12 inches (1 foot) | 304.8 mm | 30.48 cm | 0.3048 m | 1 ft |
| 18 inches | 457.2 mm | 45.72 cm | 0.4572 m | 1.5 ft |
| 24 inches (2 feet) | 609.6 mm | 60.96 cm | 0.6096 m | 2 ft |
| 36 inches (1 yard) | 914.4 mm | 91.44 cm | 0.9144 m | 3 ft |
| 60 inches (5 feet) | 1,524 mm | 152.4 cm | 1.524 m | 5 ft |
| 72 inches (6 feet) | 1,828.8 mm | 182.88 cm | 1.8288 m | 6 ft |
| 100 inches | 2,540 mm | 254 cm | 2.54 m | 8.333 ft |
Converting inches to millimetres with this tool takes just a few seconds. Follow these simple steps to get instant, accurate results for any length value in 2026.
1 Inch = 25.4 mm = 2.54 cm = 0.0254 m = 0.08333 ft
Need to convert area measurements too? Use our Acres to Square Metres Converter for land area conversions.
The inches to millimetres conversion is one of the most widely used unit conversions in the world in 2026. Below are the key industries and everyday situations where this conversion is essential.
Mechanical engineers routinely convert imperial inch dimensions on US-made components to millimetres for metric tooling and CNC machines. A shaft diameter of 1.5 inches equals 38.1 mm. Tolerance specifications on engineering drawings often require precise inch-to-mm conversion to maintain fit and function in manufactured assemblies.
Timber is sold in imperial sizes in many countries but cut using metric measurements. A standard 2×4 inch timber stud is actually 38 mm × 89 mm in metric. Carpenters and joiners converting from inch-based plans to metric workshop settings use this conversion constantly to ensure accurate cuts and joints.
Most 3D slicer software and CAD programs work in millimetres by default, while many US-based design files use inches. Converting a 2-inch component to 50.8 mm before import prevents scaling errors in 3D printing. This is one of the most common reasons hobbyists and professionals use an inch-to-mm converter in 2026.
Monitor and TV screen sizes are universally quoted in inches diagonally, while physical dimensions and bezel measurements are given in millimetres in product specifications. A 27-inch monitor has a diagonal of 685.8 mm. Converting screen sizes helps buyers compare international product listings that mix imperial and metric measurements.
Ring diameters and gemstone dimensions are specified in millimetres in most countries, but some sizing charts also use fractional inch measurements. A 0.75-inch ring diameter equals 19.05 mm. Jewellers and customers converting between international sizing standards rely on precise inch-to-mm conversion to ensure a correct fit.
Pipe nominal sizes are traditionally expressed in inches in many countries, while European standards use millimetres. A 1-inch nominal pipe has an outer diameter of approximately 33.4 mm. Plumbers working across imperial and metric systems use this conversion daily when selecting fittings, couplings, and adapters for mixed-standard installations.
The reverse conversion table below shows how many inches common millimetre values equal. This is useful when reading metric engineering drawings, working with ISO standard components, or converting metric measurements to imperial for US-specification work in 2026. For energy unit conversions, also see our BTU to Joules Converter.
| Millimetres (mm) | Inches (in) | Fractional Inches (Approx.) | Centimetres (cm) | Feet (ft) |
|---|---|---|---|---|
| 1 mm | 0.03937 in | ≈ 1/25 in | 0.1 cm | 0.003281 ft |
| 2 mm | 0.07874 in | ≈ 5/64 in | 0.2 cm | 0.006562 ft |
| 5 mm | 0.19685 in | ≈ 13/64 in | 0.5 cm | 0.016404 ft |
| 10 mm | 0.39370 in | ≈ 25/64 in | 1.0 cm | 0.032808 ft |
| 15 mm | 0.59055 in | ≈ 19/32 in | 1.5 cm | 0.049213 ft |
| 20 mm | 0.78740 in | ≈ 25/32 in | 2.0 cm | 0.065617 ft |
| 25 mm | 0.98425 in | ≈ 63/64 in | 2.5 cm | 0.082021 ft |
| 25.4 mm | 1.00000 in | 1 inch (exact) | 2.54 cm | 0.083333 ft |
| 50 mm | 1.96850 in | ≈ 1 63/64 in | 5.0 cm | 0.164042 ft |
| 100 mm | 3.93701 in | ≈ 3 15/16 in | 10.0 cm | 0.328084 ft |
| 150 mm | 5.90551 in | ≈ 5 29/32 in | 15.0 cm | 0.492126 ft |
| 200 mm | 7.87402 in | ≈ 7 7/8 in | 20.0 cm | 0.656168 ft |
| 300 mm | 11.81102 in | ≈ 11 13/16 in | 30.0 cm | 0.984252 ft |
| 500 mm | 19.68504 in | ≈ 19 11/16 in | 50.0 cm | 1.640420 ft |
| 1000 mm (1 metre) | 39.37008 in | ≈ 39 3/8 in | 100 cm | 3.280840 ft |
When converting millimetres to inches for use in imperial measurements, the result is often a decimal (e.g., 0.39370 inches). In woodworking and construction, decimal inches are sometimes expressed as fractions (e.g., 25/64). This converter displays the precise decimal result — use the fractional column in the table above for approximate fractional equivalents.
The National Institute of Standards and Technology (NIST) is the US authority on measurement standards. NIST confirms the exact definition of 1 inch = 25.4 mm as established under the International Yard and Pound Agreement of 1959, which standardised the inch globally for scientific and commercial use.
Visit NIST →ConcreteMetric provides a complete library of free unit converters covering length, area, pressure, energy, time, and more. All tools are mobile-friendly, accurate, and regularly reviewed for 2026 to ensure correct conversion factors and up-to-date reference tables.
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