# Millimetres

Enter the value to convert into the box and modify the accuracy of the conversion by selecting number of significant figures or decimal places by clicking on the boxes provided.

Conversion Formulae

The conversion formula for millimetres (cm) to inches (in) conversions is as follows:

• 1 millimetre = 0.039370079 inches

The conversion formula for inches (in) to millimetres (cm) conversions is as follows:

• 1 inch = 25.4 centimetres
Millimetres

The millimetre is 1/1000 of a metre and is a commonly used decimal measurement in engineering and the building trade.

SI Metric

### Definition

The millimetre is defined as one thousandth of a metre.

Metre

Formal: mm

### Information

The millimetre is an SI metric unit of length with the standard SI prefix milli indicating that it is 10-3 metres. Often millimetres are the smallest marked unit on rulers.

Wikipedia: Millimetre

BIPM: SI Standard Prefixes

Millimetres are used worldwide for scientific applications and in the vast majority of countries worldwide in day to day use. The major exceptions being the United States and Liberia, where the metric system has not been adopted. In the UK, Canada and other former British Commonwealth countries metric units such as the millimetre may not be used all the time.

### Conversion Formulae

• 1 millimetre = 1,000 micrometres
• 1 millimetre = 0.1 centimetres
• 1 millimetre = 0.01 decimetres
• 1 millimetre = 0.001 metres
• 1 millimetre = 0.0001 decametres
• 1 millimetre = 0.00001 hectometres
• 1 millimetre = 0.000001 kilometres
• 1 millimetre = 0.000000001 megametres

• 1 micrometre = 0.001 millimetres
• 1 centimetre = 10 millimetres
• 1 decimetre = 100 millimetres
• 1 metre = 1,000 millimetres
• 1 decametre = 10,000 millimetres
• 1 hectometre = 100,000 millimetres
• 1 kilometre = 1,000,000 millimetres
• 1 megametre = 1,000,000,000 millimetres
Inches

The inch is 1/36th of a yard, it is often used for measuring height, together with feet, in countries that use or have used Imperial or US Customary measurements.

### Unit System

Imperial & US Customary

### Definition

The inch is defined as 1/36th of a yard.

Yard

### Abbreviation

Formal: in

The abbreviation ins is sometimes seen for greater than one inch.

### Information

The inch derives from Roman unciae (twelfth parts of a Roman foot) with Roman measurements being in use in Great Britain this unit may well have continued in use after the Romans left.

The earliest recorded definition of the inch defines it as three barleycorns in length, however this definition was around 1300 in the 'The Composition of Yards and Perches' according to some sources. However the Liber Horn (1311), an early book of English statutes, suggests that the inch was defined 1/36th part of an iron yard held by the king.

At some point prior to the implementation of the Weights and Measures Act of 1824 the inch had become defined as 1/36th of a yard via 36in = 3ft = 1yd and the use of standard yards. The Weights and Measures Act of 1824 was used to remove any ambiguity of definitions left by prior statutes.

Wikipedia: Inch

Wikipedia: Liber Horn (1311) author Andrew Horn

UK National Archives: Liber Horn

Wikipedia: Composition of Yards and Perches

Wikipedia: UK Weights and Measures Acts

Inches are a standard unit of length in the United States and Liberia and are still used informally in the United Kingdom and other British Commonwealth countries that formerly used Imperial units as standard.

### Conversion Formulae

• 1 inch = 0.25 hands
• 1 inch = 0.083333333 feet
• 1 inch = 0.027777778 yards
• 1 inch = 0.001262626 chains
• 1 inch = 0.000126263 furlongs
• 1 inch = 0.000015783 miles

Conversions accurate to 9 decimal places.

• 1 hand = 4 inches
• 1 foot = 12 inches
• 1 yard = 36 inches
• 1 chain = 792 inches
• 1 furlong = 7,920 inches
• 1 mile = 63,360 inches

Conversions accurate to 9 decimal places.

Common Conversions mm to in
 mm in 1 0.04 2 0.08 3 0.12 4 0.16 5 0.20 6 0.24 7 0.28 8 0.31 9 0.35 10 0.39
 mm in 10 0.39 20 0.79 30 1.18 40 1.57 50 1.97 60 2.36 70 2.76 80 3.15 90 3.54 100 3.94
 mm in 100 3.94 200 7.87 300 11.81 400 15.75 500 19.69 600 23.62 700 27.56 800 31.50 900 35.43 1,000 39.37
Common Conversions in to mm
 in mm 1 25.40 2 50.80 3 76.20 4 101.60 5 127.00 6 152.40 7 177.80 8 203.20 9 228.60 10 254.00 11 279.40 12 304.80
 in mm 12 304.80 24 609.60 36 914.40 48 1,219.20 60 1,524.00 72 1,828.80 84 2,133.60 96 2,438.40 108 2,743.20 120 3,048.00 132 3,352.80 144 3,657.60