About mm-to-inches.net
Last reviewed: July 18, 2026
What this site does
mm-to-inches.net provides browser-based millimeter/inch converters, charts, worksheets, and practical reference pages for people who need quick dimensional conversions.
This website is published under the mm-to-inches.net name. We do not claim an individual author, company, professional credential, certification, or affiliation that has not been verified and approved for public use.
Conversion basis
Our calculations use the exact relationship:
1 inch = 25.4 millimeters
NIST explains that the standard inch has been exactly equivalent to 25.4 mm since July 1, 1959:
https://www.nist.gov/pml/owm/si-units-length
For millimeters to inches, the calculator divides millimeters by 25.4. For inches to millimeters, it multiplies inches by 25.4.
Precision, fractions, and tolerances
The underlying factor is exact, but a displayed result may be rounded to the selected number of decimal places. Fractional-inch displays use a selected denominator and may be an approximation. Nearby tool, drill, material, or product sizes are practical references, not exact substitutes unless the displayed measurements are equal.
For machining, engineering, manufacturing, medical, safety-critical, contractual, or regulated work, verify the result independently and use the tolerance, standard, and qualified review required for your application.
How pages are created and reviewed
Our editorial method is to:
- calculate from the exact 25.4 mm-per-inch relationship;
- distinguish exact values from rounded decimals and approximate fractions;
- provide page-specific context, comparisons, tolerances, or examples where they add practical value;
- avoid presenting number substitution alone as original editorial analysis;
- check visible answers, formulas, tables, FAQs, and structured data for consistency; and
- review corrections and update the fixed “Last reviewed” date when the method or substantive copy changes.
We do not promise that every page is error-free. We correct confirmed mistakes and clarify ambiguous wording when appropriate.
Corrections and contact
To report a conversion or content issue, email [email protected] and include:
- the page URL;
- the input and displayed result;
- the result you expected;
- the precision or fraction setting; and
- a supporting standard or source, if available.
The current Contact page opens your email application rather than submitting a message to a site database.
Advertising and independence
The website does not currently load advertising scripts. If advertising is introduced later, advertising status and data practices will be disclosed in the Privacy and Cookie Policies. Advertising will not change the mathematical conversion factor or authorize claims of endorsement by an advertiser, Google, NIST, or another third party.