About DecimalToInches.com
DecimalToInches.com converts between decimals, fractions and millimetres exactly, for anyone who measures for a living or for a project. Every result comes from real arithmetic on the numbers you enter, not a rounded approximation.
Built for Anyone Who Measures
A carpenter reading a tape measure, a machinist holding a thousandth-inch tolerance, a student learning what 0.75 looks like as a fraction, an engineer converting an imported part's metric spec to inches — all of them land on this site looking for the same thing: a fast, correct answer without ads getting in the way of the number.
The site is organized into six clusters of tools — decimal-fraction conversion, decimal inches and feet, millimetres and inches, reference charts, drill sizes, and machinist and workshop references — so whichever direction you're converting, there's a dedicated calculator for it rather than one crowded, general-purpose tool trying to do everything at once.
Exact Arithmetic, Not Approximation
Floating-point math can quietly introduce rounding error into numbers that should be exact — this site is built specifically to avoid that.
Decimal-to-fraction conversions are derived directly from a decimal's own digits, so 0.1 becomes exactly 1/10 rather than the nearest power-of-two fraction to how a computer actually stores 0.1 internally. Every millimetre conversion multiplies or divides by 25.4 — the exact, internationally defined number of millimetres in one inch since 1959 — never a rounded stand-in. Where a result genuinely has to be rounded, such as fitting a decimal to the nearest 1/64" for a tape measure, the calculator shows the exact rounding error alongside the answer rather than hiding it.
Read the privacy policy for what data, if any, is collected while you use these tools.
The Six Tool Clusters
Every calculator and chart on the site falls into one of these six categories.
Frequently Asked Questions
Who is DecimalToInches.com built for?
Anyone converting between decimals, fractions and millimetres: woodworkers and framers reading a tape measure, machinists holding a tolerance, students learning fractions, and engineers cross-referencing an imperial part against a metric drawing.
How accurate are the calculators on this site?
Every calculator derives its result from exact arithmetic rather than rounded floating-point math where it matters — decimal-to-fraction conversions work from the decimal's own digits, and every metric conversion uses the exact, internationally defined 25.4 mm-per-inch constant.
Do I need to create an account to use the calculators?
No. Every tool on this site runs entirely in your browser, with no account, no sign-up and no server-side processing of the numbers you enter.
How do I report an error or suggest a new tool?
Use the contact page — every message goes directly to the team, and corrections are the fastest way to help everyone who uses the site after you.
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