Inches to MM Converter
Convert inches to millimeters precisely. Ideal for engineering drawings and technical specs.
Formula: in × 25.4 = mm
Common Conversions
Why Use Our Inches to MM Converter?
Instant Results
Type any inches value and see the millimeters result immediately as you type.
Highly Accurate
Uses the exact conversion factor. in × 25.4 = mm
Swap Direction
Easily convert Millimeters back to Inches with the swap button. No need to visit a different page.
One-Click Copy
Copy the converted result to your clipboard instantly with the Copy button.
Common Values Table
See a quick reference table of 9 common inches values and their millimeters equivalents.
100% Private
All conversions happen in your browser. Nothing is sent to a server or stored anywhere.
Frequently Asked Questions
How many millimeters in a inche?
1 in = see the formula above mm. Use the formula: in × 25.4 = mm.
How to convert inches to millimeters?
To convert inches to millimeters, use the formula: in × 25.4 = mm. For example, 1 in = 25.4 mm.
Is this inches to mm converter accurate?
Yes. The converter uses the internationally accepted exact conversion factor. The result is accurate to at least 6 significant figures.
Can I convert millimeters back to inches?
Yes. Click the "Swap direction" button to reverse the conversion. The current result becomes the new input automatically.
Does this work on mobile?
Yes. The converter works on all devices — phones, tablets, and desktops. All calculations happen in your browser.
Is my data stored anywhere?
No. All conversions run entirely in your browser. Nothing is uploaded, logged, or stored.