Is an inch exactly 2.54 cm?

Yes, exactly. Since the international yard and pound agreement of 1959 the inch is defined as 25.4 mm by definition rather than by measurement, so every imperial length converts to metric exactly and the rounding you see is only in the display.

What is the difference between a nautical mile and a mile?

A nautical mile is 1,852 m exactly, defined as one minute of latitude, against 1,609.344 m for a statute mile. It is about fifteen percent longer, which is why distances at sea and in the air never mix the two.

Conversionsmeasurement

Length Converter

Length and distance between metric and imperial units, on the exact defined factors. An inch is exactly 0.0254 metres, not an approximation.

Also called: metre to feet, cm to inches, distance converter.

Result

3.28084

1 Metre is 3.28084 Foot. The factor is 3.280839895, and the inverse is 0.3048. The table below gives the same value in every length unit at once.

Conversion factor

3.280839895

Inverse factor

0.3048

Value in m

Converting from

Metre

Converting to

Foot

Dimension

length

How this is calculated

The same value in every length unit

Unit	Value
Millimetre	1,000
Centimetre	100
Metre	1
Kilometre	0
Inch	39.37
Foot	3.28
Yard	1.09
Mile	0

Method and background

How this is calculated

Every unit is expressed against the metre, so any pair converts consistently. The imperial units have been defined in terms of the metre since 1959, which means these conversions are exact rather than measured.

result = value * factor_from / factor_to

k: Each unit's size in m

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

1 metre in feet

Value: 1
From: Metre
To: Foot

Result3.28084

1/0.3048, exact by definition

Open this example

a mile in kilometres

Value: 1
From: Mile
To: Kilometre

Result1.609344

exact by the 1959 international yard and pound agreement

Open this example

converting to itself changes nothing

Value: 42
From: Metre
To: Metre

Result42

degenerate case

Open this example

Frequently asked questions

Is an inch exactly 2.54 cm?: Yes, exactly. Since the international yard and pound agreement of 1959 the inch is defined as 25.4 mm by definition rather than by measurement, so every imperial length converts to metric exactly and the rounding you see is only in the display.
What is the difference between a nautical mile and a mile?: A nautical mile is 1,852 m exactly, defined as one minute of latitude, against 1,609.344 m for a statute mile. It is about fifteen percent longer, which is why distances at sea and in the air never mix the two.