Inches to mm converter

Category: Various Measurements/Units
- May 14, 2025
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Convert between inches and millimeters easily with this calculator. Useful for engineering, construction, manufacturing, and international measurement standards.

Length Conversion

Display Options

About Length Measurements

Measurement systems vary around the world. The United States primarily uses imperial units like inches, while most other countries use the metric system with millimeters.

Conversion Facts
  • 1 inch = 25.4 millimeters (exact conversion)
  • 1 millimeter = 0.03937 inches
  • 1 foot = 304.8 millimeters (12 inches)
  • 1 yard = 914.4 millimeters (36 inches)
  • 1 meter = 39.37 inches (1000 millimeters)
Common Applications
  • Engineering: Technical drawings, precision machinery, tolerances
  • Manufacturing: Component dimensions, material thickness
  • Construction: Building materials, architectural plans
  • Woodworking: Lumber dimensions, furniture making
  • Electronics: Circuit board dimensions, component sizing
Fraction to Decimal Conversion
Fraction (inch) Decimal (inch) Millimeters
1/16" 0.0625" 1.5875 mm
1/8" 0.125" 3.175 mm
1/4" 0.25" 6.35 mm
3/8" 0.375" 9.525 mm
1/2" 0.5" 12.7 mm
5/8" 0.625" 15.875 mm
3/4" 0.75" 19.05 mm
7/8" 0.875" 22.225 mm
1" 1.0" 25.4 mm

Inches to Millimeters Conversion Calculator

Formula to Convert Inches to Millimeters:

millimeters = inches × 25.4

Formula to Convert Millimeters to Inches:

inches = millimeters ÷ 25.4

What This Calculator Does

This inches to mm converter is a practical unit conversion tool that helps you instantly convert measurements between inches and millimeters. Whether you're working with construction plans, engineering drawings, or product specifications, this conversion calculator eliminates guesswork by delivering precise value conversions at your fingertips.

It’s ideal for:

  • Engineers and designers translating technical specs
  • Builders and woodworkers matching measurement standards
  • DIYers needing to convert imperial to metric units
  • Anyone handling global documentation or products

How to Use the Calculator

Follow these simple steps to convert your values accurately:

  • Select the input unit: Choose between inches and millimeters as your starting point.
  • Choose the target unit: Pick the unit you want to convert to.
  • Enter a numeric value: Input the number you wish to convert.
  • Set decimal precision: Choose how many decimal places you want in the result.
  • Click “Convert”: View the result, complete with the formula used and a simple explanation.
  • Optional: Click “Swap Units” to reverse the conversion direction instantly.

Why This Tool is Useful

This measurement converter is a time-saving resource that brings clarity and consistency to any task requiring length conversions. Instead of relying on charts or manual calculations, the tool ensures:

  • Accurate results based on the exact conversion factor
  • Visual feedback of the applied formula and result
  • Common reference values to help contextualize the measurement

Perfect for quick unit conversions during shopping, measurements in technical work, or verifying specifications across different standards.

Frequently Asked Questions

What is the exact conversion between inches and millimeters?

1 inch equals exactly 25.4 millimeters. This is a standardized international conversion factor.

Can I convert millimeters to inches using this calculator?

Yes. Just select “Millimeters” in the “From” dropdown and “Inches” in the “To” dropdown to perform the reverse conversion.

What are decimal places used for?

Decimal places allow you to control the precision of your result. For example, rounding to 2 decimal places gives a cleaner, more practical number for many uses.

How does this calculator compare to a chart?

This conversion helper gives you dynamic, on-demand results tailored to your specific input — unlike static charts which only show a fixed list of values.

What if I enter the same unit in both fields?

The tool will simply return your original value and explain that no conversion is necessary.

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This conversion tool is a reliable resource whenever you need to convert measurements efficiently and accurately.