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Examples: "10.5", "4 3/4", "15/16"

Millimeters-mm
Centimeters-cm
Meters-m
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About

In construction, machining, and international trade, the divide between Imperial and Metric systems creates constant friction. The challenge is not just converting numbers, but handling the format of the inputs. Inches are rarely clean decimals; they are often mixed fractions (e.g., 5 1/2") or complex fractions (e.g., 27/64") found on drill bits and fasteners. Converting these manually requires two steps: fraction-to-decimal, then decimal-to-metric.

This tool automates the entire workflow. It acts as a universal parser, accepting integers, decimals, and mixed fractions. By outputting Millimeters, Centimeters, and Meters simultaneously, it eliminates the need for multiple searches. Whether you are a carpenter framing a wall or a machinist selecting a drill bit, this tool ensures the conversion is precise to industry standards ($1 \text{ inch} = 25.4 \text{ mm}$).

inch converter fraction calculator construction tool machining imperial to metric

Formulas

The core standard defined in 1959 establishes the exact value of the inch.

1 inch = 25.4 mm

To handle fractions, the tool first computes the decimal sum:

Input = Integer +
NumeratorDenominator

Reference Data

Fractional InchDecimal InchMillimeters (mm)
1/64"0.01560.3969
1/32"0.03130.7938
1/16"0.06251.5875
1/8"0.12503.1750
1/4"0.25006.3500
3/8"0.37509.5250
1/2"0.500012.7000
5/8"0.625015.8750
3/4"0.750019.0500
7/8"0.875022.2250
1"1.000025.4000

Frequently Asked Questions

Yes. The tool understands mixed fractions (e.g., "5 1/2"), simple fractions (e.g., "3/4"), and standard decimals (e.g., "5.5"). Space between the whole number and the fraction is required.
Yes. Since the international yard and pound agreement of 1959, the inch has been defined as exactly 25.4 millimeters. There is no rounding involved in the definition.
The math engine supports any fraction denominator (e.g., 1/128, 1/1000). The accuracy is limited only by standard floating-point precision, making it suitable for high-tolerance machining.