Millimetre to inch calculator
Millimetre to inch calculator
Convert millimetres to decimal inches and selectable fractional inches, including rounding error and a practical reference table. Inputs, formula and interpretation are separated so you can verify the result before using it for a configurable part.
Calculate
Schematic illustration – not to scale.
Schematic illustration – not to scale.
Formula
in = mm / 25.4
Step by step
- Enter the measured or planned values with their units.
- Check the formula with substituted values in the result area.
- Copy the parameters or open a related product for configuration.
Complete worked example
Worked example with typical workshop values: insert the inputs, apply in = mm / 25.4 and compare the result with the reference table.
| 2 | 30 | 60 mm |
| 1.5 | 40 | 60 mm |
| 25.4 mm | 1 in |
Assumptions and limitations
- Conversions use 1 in = 25.4 mm; fractions are rounded display values.
Common input mistakes
- Decimal comma and point are accepted, but do not type units into numeric fields.
- For gears, the tooth count must be a whole number in practice.
FAQ
Are metric and UNC/UNF threads interchangeable?
No. Similar diameters do not mean profile, pitch and tolerance are compatible.
Can I manufacture directly from this result?
Use the value as a calculation and configuration aid. Loaded or standards-critical parts need engineering review.
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