length · International · Modern

millimetre

mmexact

Record: M004
Definition quality: Standardized
Conversion mode: multiplicative
Calculator: Fully calculable

Definition

1 mm = 0.001 m by the SI prefix milli-.

Reference value

One millimetre is equal to 0.001 metres.

History & use

SI-prefixed decimal submultiple of the metre.

Modern use

Current-use record in the project inventory; exact scope should follow the definition and regional/system context shown here.

Did you know?

An international inch is exactly 25.4 millimetres.

Sources & evidence

Source tier Tier A · confidence High

Related measurements

metre

length · International · Modern

SI base unit of length. Its definition fixes the speed of light in vacuum at exactly 299,792,458 m/s, with the second defined from the caesium-133 hyperfine frequency.

kilometre

length · International · Modern

1 km = 1000 m by the SI prefix kilo-.