Inch (in)
An inch is a unit in US customary and imperial measure, standardized internationally as exactly 2.54 centimeters.
Inches dominate screen sizes, lumber dimensions, and everyday measuring tapes in the United States.
Inch to Millimeter
Convert inch to millimeter instantly. Type in either field — results update live.
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Length Inch Millimeter
1 inch = 25.4 millimeters
Unit
Unit
Conversion table
Selected in values converted to mm using the exact factor from this tool.
| in | mm |
|---|---|
| 0.01 | 0.254 |
| 0.1 | 2.54 |
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1,270 |
| 100 | 2,540 |
| 1,000 | 25,400 |
How to convert
Exact conversion factors in both directions, plus a worked example.
1 in = 25.4 mm
1 mm = 0.0393700787 in
To convert inch to millimeter, multiply by 25.4.
To convert millimeter to inch, multiply by 0.0393700787.
Example: convert 15 in to mm
15 × 25.4 = 381 mm
About these units
Short background on the units used in this conversion.
Millimeter (mm)
A millimeter is one thousandth of a meter — the metric workhorse for fine measurements and manufacturing tolerances.
Millimeters are used in engineering drawings, rainfall totals, and anywhere sub-centimeter precision matters.
Frequently asked questions
How many millimeters are in one inch?
One inch equals 25.4 millimeters. Multiply your inches value by 25.4 to convert to millimeters.
What is the conversion formula?
mm = in × 25.4The reverse is
in = mm × 0.0393700787, using the same exact factors as this converter.Is this Inch to Millimeter converter private?
Yes. All calculations run locally in your browser. Nothing you type is sent to a server.
All inch conversions
Jump to any length conversion starting from inch — including the reverse direction and every other unit in our dataset.
millimeter (mm) → inch (in)
inch (in) → kilometer (km)inch (in) → meter (m)inch (in) → decimeter (dm)inch (in) → centimeter (cm)inch (in) → micrometer (µm)inch (in) → nanometer (nm)inch (in) → mile (mi)inch (in) → yard (yd)inch (in) → foot (ft)inch (in) → light year (ly)inch (in) → exameter (Em)inch (in) → petameter (Pm)inch (in) → terameter (Tm)inch (in) → gigameter (Gm)inch (in) → megameter (Mm)inch (in) → hectometer (hm)inch (in) → dekameter (dam)inch (in) → micron (µ)inch (in) → picometer (pm)inch (in) → femtometer (fm)inch (in) → attometer (am)inch (in) → megaparsec (Mpc)inch (in) → kiloparsec (kpc)inch (in) → parsec (pc)inch (in) → astronomical unit (AU)inch (in) → league (lea)inch (in) → nautical league (uk)inch (in) → nautical league (int.)inch (in) → league (statute) (st.league)inch (in) → nautical mile (uk) (NM-UK)inch (in) → nautical mile (international) (nmi)inch (in) → mile (statute)inch (in) → mile (us survey)inch (in) → mile (roman) (mi-Roman)inch (in) → kiloyard (kyd)inch (in) → furlong (fur)inch (in) → furlong (us survey)inch (in) → chain (ch)inch (in) → chain (us survey)inch (in) → ropeinch (in) → rod (rd)inch (in) → rod (us survey)inch (in) → perchinch (in) → poleinch (in) → fathom (fath)inch (in) → fathom (us survey)inch (in) → ellinch (in) → foot (us survey)inch (in) → link (li)inch (in) → link (us survey)inch (in) → cubit (uk)inch (in) → handinch (in) → span (cloth)inch (in) → finger (cloth)inch (in) → nail (cloth)inch (in) → inch (us survey)inch (in) → barleycorninch (in) → milinch (in) → microinch (µin)inch (in) → angstrom (Å)inch (in) → a.u. of lengthinch (in) → x-unit (X)inch (in) → fermi (F)inch (in) → arpentinch (in) → picainch (in) → point (pt)inch (in) → twipinch (in) → alninch (in) → famninch (in) → caliber (cl)inch (in) → centiinch (cin)inch (in) → keninch (in) → russian archin (archin)inch (in) → roman actus (actus)inch (in) → vara de tareainch (in) → vara conuquerainch (in) → vara castellanainch (in) → cubit (greek)inch (in) → long reedinch (in) → reedinch (in) → long cubitinch (in) → handbreadthinch (in) → fingerbreadthinch (in) → planck lengthinch (in) → electron radius (classical) (re)inch (in) → bohr radius (b)inch (in) → earth's equatorial radius (R⊕eq)inch (in) → earth's polar radius (R⊕pol)inch (in) → earth's distance from suninch (in) → sun's radius