Millimeters (mm)
The millimeter (also spelled millimetre) is a metric unit of length equal to one thousandth of a meter, or one tenth of a centimeter.
Convert millimeters to any length unit
1 millimeter = 0.03937007874 inches
Quick facts
- Unit
- Millimeter (plural: millimeters)
- Symbol
- mm
- Measures
- Length / Distance
- System
- Metric (SI)
- Equals
- 0.001 meters
- Definition
- One thousandth of a meter (10⁻³ m).
- Also written
- millimetre
1 millimeter in other units
| Inches | 0.03937007874 in |
| Meters | 0.001 m |
| Centimeters | 0.1 cm |
| Feet | 0.003280839895 ft |
| Kilometers | 0.000001 km |
| Miles | 6.2137119 × 10-7 mi |
| Yards | 0.001093613298 yd |
| Micrometers | 1,000 µm |
What is a millimeter?
The millimeter (also spelled millimetre) is a metric unit of length equal to one thousandth of a meter, or one tenth of a centimeter. It is the smallest mark on a standard metric ruler.
A millimeter is about the thickness of a credit card or a grain of sand, and an inch is exactly 25.4 millimeters. Engineers, machinists and designers use millimeters because they are small enough to be precise without needing decimals.
Where the millimeter sits among length units
The millimeter is number 24 of 231 on our scale of length units, ordered from smallest to largest.
What millimeters are used for
- Engineering and architectural drawings (all dimensions are usually in mm)
- Rainfall measurement (1 mm of rain = 1 liter per square meter)
- Camera lens focal lengths (50 mm lens) and film formats (35 mm)
- Jewelry, screws, drill bits and tire tread depth
- Smartphone and screen thickness
Millimeters in real life
- A credit card is about 0.76 mm thick
- The tip of a sharp pencil is about 0.5 mm wide
- A US dime is 1.35 mm thick
- Legal minimum tire tread depth in many countries is 1.6 mm
One millimeter is about 3.3 dust mites laid end to end, or about 2 grains of sand laid end to end, or about 13 human hairs side by side laid end to end, or about 133 red blood cells laid end to end.
Top millimeter conversions
- Millimeters to inches
- Millimeters to meters
- Millimeters to centimeters
- Millimeters to feet
- Millimeters to kilometers
- Millimeters to miles
- Millimeters to yards
- Millimeters to micrometers
- Millimeters to nanometers
- Millimeters to nautical miles
- Millimeters to light-years
- Millimeters to astronomical units
Common amounts of millimeters
- 0.1 mm
- 0.2 mm
- 0.3 mm
- 0.4 mm
- 0.5 mm
- 0.6 mm
- 0.7 mm
- 0.8 mm
- 0.9 mm
- 1 mm
- 1.5 mm
- 2 mm
- 2.5 mm
- 3 mm
- 3.5 mm
- 4 mm
- 4.5 mm
- 5 mm
- 6 mm
- 7 mm
- 7.5 mm
- 8 mm
- 9 mm
- 10 mm
- 11 mm
- 12 mm
- 13 mm
- 14 mm
- 15 mm
- 16 mm
- 17 mm
- 18 mm
- 19 mm
- 20 mm
- 21 mm
- 22 mm
- 23 mm
- 24 mm
- 25 mm
- 26 mm
- 27 mm
- 28 mm
- 29 mm
- 30 mm
- 31 mm
- 32 mm
- 33 mm
- 34 mm
- 35 mm
- 36 mm
- 37 mm
- 38 mm
- 39 mm
- 40 mm
- 41 mm
- 42 mm
- 43 mm
- 44 mm
- 45 mm
- 46 mm
- 47 mm
- 48 mm
- 49 mm
- 50 mm
- 51 mm
- 52 mm
- 53 mm
- 54 mm
- 55 mm
- 56 mm
- 57 mm
- 58 mm
- 59 mm
- 60 mm
- 61 mm
- 62 mm
- 63 mm
- 64 mm
- 65 mm
- 66 mm
- 67 mm
- 68 mm
- 69 mm
- 70 mm
- 71 mm
- 72 mm
- 73 mm
- 74 mm
- 75 mm
- 76 mm
- 77 mm
- 78 mm
- 79 mm
- 80 mm
- 81 mm
- 82 mm
- 83 mm
- 84 mm
- 85 mm
- 86 mm
- 87 mm
- 88 mm
- 89 mm
- 90 mm
- 91 mm
- 92 mm
- 93 mm
- 94 mm
- 95 mm
- 96 mm
- 97 mm
- 98 mm
- 99 mm
- 100 mm
- 110 mm
- 120 mm
- 130 mm
- 140 mm
- 150 mm
- 160 mm
- 170 mm
- 180 mm
- 190 mm
- 200 mm
- 210 mm
- 220 mm
- 230 mm
- 240 mm
- 250 mm
- 260 mm
- 270 mm
- 280 mm
- 290 mm
- 300 mm
- 310 mm
- 320 mm
- 330 mm
- 340 mm
- 350 mm
- 360 mm
- 370 mm
- 380 mm
- 390 mm
- 400 mm
- 410 mm
- 420 mm
- 430 mm
- 440 mm
- 450 mm
- 460 mm
- 470 mm
- 480 mm
- 490 mm
- 500 mm
- 600 mm
- 700 mm
- 800 mm
- 900 mm
- 1,000 mm
- 1,200 mm
- 1,500 mm
- 2,000 mm
- 2,500 mm
- 3,000 mm
- 4,000 mm
- 5,000 mm
- 10,000 mm
Convert millimeters to all 230 other units
Metric (SI)
Imperial & US customary
- mm to in
- mm to ft
- mm to mi
- mm to yd
- mm to ftm
- mm to fur
- mm to hh
- mm to th
- mm to ch
- mm to lea
- mm to rd
- mm to cubit
- mm to barleycorn
- mm to li
- mm to span
- mm to line
- mm to ell
- mm to palm
- mm to Ramsden's chain
- mm to finger
- mm to nail
- mm to shaftment
US survey
Nautical
Astronomical
- mm to ly
- mm to au
- mm to pc
- mm to kpc
- mm to Mpc
- mm to R⊕
- mm to ls
- mm to light-minute
- mm to LD
- mm to R☉
- mm to Gpc
- mm to light-day
- mm to light-hour
- mm to RJ
- mm to light-week
- mm to Hubble length
- mm to siriometer
Scientific & atomic
Ancient
- mm to Roman mile
- mm to royal cubit
- mm to stadion
- mm to Biblical cubit
- mm to Roman foot
- mm to Greek foot
- mm to Roman pace
- mm to parasang
- mm to Egyptian common cubit
- mm to Egyptian digit
- mm to Egyptian palm
- mm to Gallic league
- mm to Greek cubit
- mm to Greek finger
- mm to Roman cubit
- mm to Roman digit
- mm to Roman inch
- mm to Roman palm
- mm to Roman stadium
- mm to Roman step
- mm to handbreadth
- mm to Biblical finger
- mm to Biblical parasang
- mm to Biblical span
- mm to Greek palm
- mm to Greek span
- mm to Sabbath day's journey
- mm to Talmudic mil
- mm to bema
- mm to beru
- mm to day's journey
- mm to diaulos
- mm to dichas
- mm to hippikon
- mm to iteru
- mm to khet
- mm to kondylos
- mm to kush
- mm to nindan
- mm to orgyia
- mm to plethron
- mm to pygme
- mm to reed
- mm to remen
- mm to shu-si
- mm to ush
East & Southeast Asian
- mm to 里
- mm to 尺
- mm to 寸
- mm to 尺
- mm to 里
- mm to 間
- mm to 寸
- mm to wa
- mm to 리
- mm to 丈
- mm to 步
- mm to 分
- mm to 厘
- mm to 分
- mm to 치
- mm to 町
- mm to 자
- mm to 丈
- mm to khuep
- mm to kujirajaku
- mm to nio
- mm to sen
- mm to sok
- mm to 引
- mm to yot
- mm to 厘
- mm to 푼
- mm to 毫
- mm to 忽
- mm to kraphiat
- mm to 毛
- mm to 丝
South Asian & Middle Eastern
- mm to gaj
- mm to kos
- mm to yojana
- mm to angul
- mm to farsakh
- mm to hasta
- mm to arsin
- mm to barid
- mm to danda
- mm to dhira
- mm to qasaba
European (pre-metric)
- mm to Swedish mil
- mm to versta
- mm to arshin
- mm to lieue
- mm to ligne
- mm to pied du roi
- mm to sazhen
- mm to toise
- mm to Irish mile
- mm to Prussian mile
- mm to Russian mile
- mm to Scottish mile
- mm to pouce
- mm to vershok
- mm to Danish mile
- mm to French point
- mm to Prussian ell
- mm to Prussian foot
- mm to Prussian inch
- mm to Prussian rod
- mm to Rhineland rod
- mm to Russian foot
- mm to Swiss hour
- mm to aln
- mm to aune
- mm to duim
- mm to dyuym
- mm to famn
- mm to liniya
- mm to pyad
- mm to Welsh mile
- mm to fjardingsvag
- mm to tochka
Spanish & Portuguese
- mm to Castilian vara
- mm to Spanish league
- mm to Texas vara
- mm to pulgada
- mm to Castilian foot
- mm to Mexican vara
- mm to braca
- mm to legua
- mm to Portuguese foot
- mm to Portuguese vara
- mm to palmo
- mm to polegada
- mm to Spanish pace
- mm to linea
- mm to linha
- mm to punto
Everyday comparisons
- mm to American football field
- mm to marathon
- mm to smoot
- mm to Earth circumference
- mm to Eiffel Tower height
- mm to Olympic pool length
- mm to banana
- mm to double-decker bus
- mm to soccer pitch length
- mm to Mount Everest height
- mm to blue whale length
- mm to credit card length
- mm to human hair width
- mm to Burj Khalifa height
- mm to Earth diameter
- mm to Empire State Building height
- mm to Statue of Liberty height
- mm to human height
- mm to giraffe height
- mm to grain of rice
- mm to paperclip length
- mm to pencil length
- mm to sheppey
- mm to smartphone length
Convert to millimeters
- Inches to millimeters
- Meters to millimeters
- Centimeters to millimeters
- Feet to millimeters
- Kilometers to millimeters
- Miles to millimeters
- Yards to millimeters
- Micrometers to millimeters
- Nanometers to millimeters
- Nautical miles to millimeters
- Light-years to millimeters
- Astronomical units to millimeters
Frequently asked questions
What is a millimeter?
The millimeter (also spelled millimetre) is a metric unit of length equal to one thousandth of a meter, or one tenth of a centimeter.
How is the millimeter defined?
One thousandth of a meter (10⁻³ m).
How many inches are in a millimeter?
One millimeter equals 0.03937007874 inches.
How many meters are in a millimeter?
One millimeter equals 0.001 meters.
How many centimeters are in a millimeter?
One millimeter equals 0.1 centimeters.