Overview
This converter turns inch measurements into millimeters using the standard exact factor of 25.4. It is useful when you need a precise metric value from a fractional, decimal, or whole-inch input. Use it for dimensions from drawings, hardware sizes, material specs, or packaged products that list measurements in inches. The result is shown in millimeters so you can compare values in a metric workflow without doing the multiplication yourself.
Use cases
- Machine part dimensionsConvert a shaft, bracket, or panel size from inch-based drawings into millimeters for fabrication or inspection.
- Product specification sheetsTranslate imported item dimensions listed in inches into metric units for catalogs, labels, or purchasing records.
- Woodworking and shop setupCheck fence positions, bit sizes, or clearance gaps when a project uses inch measurements but your tools read in millimeters.
- Technical drawings and CAD notesMatch inch-based dimensions to a metric workspace when reviewing plans, revisions, or annotation values.
How it works
- 1
Type an inch value into the input field.
- 2
The tool multiplies the value by 25.4.
- 3
Read the result in millimeters and copy it into your notes, spec sheet, or calculation.
Examples
Decimal input
Input: 2.5
Output: 63.5 mm
A decimal inch value converted directly into millimeters.
Whole number input
Input: 7
Output: 177.8 mm
Useful for larger measurements from parts, pipes, or panels.
Fraction-style value
Input: 0.75
Output: 19.05 mm
Converts three-quarters of an inch into a metric result.
FAQ
What formula does this converter use?
It uses the exact relation 1 inch = 25.4 millimeters, so the inch value is multiplied by 25.4.
Can I enter decimals or fractions?
Decimals are accepted directly. If your source value is written as a fraction, convert it to decimal form first, such as 1/2 = 0.5.
Why does the result sometimes show decimals?
Many inch values do not convert to a whole number of millimeters. The decimal part is part of the exact metric equivalent.
What is a common mistake when reading the result?
Do not round too early. For parts, drawings, or fit checks, keep the full value until you know how many digits you need.
Does this tool change inches into centimeters too?
No. It converts inches to millimeters only. For centimeters, divide the millimeter result by 10.