Millimetre

Ruler with millimeter and centimeter marks

EM Spectrum Properties edit.svg

Millimetre (International spelling as used by the International Bureau of Weights and Measures; American spelling: millimeter, symbol: mm) is a unit of length in the metric system, equal to one thousandth of a metre (the SI base unit of length).

Definition

One millimetre is defined as one thousandth of a metre, which is the base unit of length in the International System of Units (SI). The millimetre is a common unit of measurement in many fields, including engineering, physics, and medicine.

Usage

Millimetres are widely used in various applications:

• In engineering, millimetres are used for precise measurements and specifications.
• In medicine, millimetres are used to measure small distances, such as the size of a lesion or the thickness of a tissue.
• In physics, millimetres are used to measure wavelengths of electromagnetic waves, such as microwaves and infrared radiation.

Conversion

The millimetre can be converted to other units of length:

• 1 millimetre = 0.001 metre
• 1 millimetre = 0.1 centimetre
• 1 millimetre = 1,000 micrometres (µm)
• 1 millimetre = 1,000,000 nanometres (nm)

Related Units

• Centimetre: 1 centimetre = 10 millimetres
• Metre: 1 metre = 1,000 millimetres
• Kilometre: 1 kilometre = 1,000,000 millimetres

Applications

Millimetres are used in various fields:

• In construction, millimetres are used for precise measurements of materials and components.
• In manufacturing, millimetres are used to ensure the accuracy of parts and products.
• In science, millimetres are used to measure small distances and dimensions in experiments and research.

See Also

• Metric system
• International System of Units
• Length
• Centimetre
• Metre
• Micrometre
• Nanometre