Length Converter

What is a length converter?

A length converter changes a distance from one unit of measurement into all the others at once — millimetres, centimetres, metres, kilometres, inches, feet, yards and miles. Instead of looking up a separate factor for every pair of units, you enter a single value, pick the unit it is in, and the tool returns every equivalent length in one view. This makes it ideal for switching between the metric system used in most of the world and the imperial system still common in the United States.

How does the length converter work?

The converter uses a base-unit method: it turns your value into metres first, then divides by each target unit’s size in metres. The metre is the SI base unit of length, so every other unit can be defined as a fixed multiple of it.

The exact formula is:

metres = value × (size of source unit in metres)

result = metres ÷ (size of target unit in metres)

Each unit has a fixed conversion factor (its size in metres):

Unit	Symbol	Metres per unit	System
Millimetre	mm	0.001	Metric
Centimetre	cm	0.01	Metric
Metre	m	1	Metric (base)
Kilometre	km	1000	Metric
Inch	in	0.0254	Imperial
Foot	ft	0.3048	Imperial
Yard	yd	0.9144	Imperial
Mile	mi	1609.344	Imperial

The imperial factors are exact by definition. Since the 1959 international yard and pound agreement, one inch is defined as exactly 0.0254 m, which makes one foot 0.3048 m, one yard 0.9144 m and one mile 1609.344 m. Results are rounded to 7 significant figures for a clean display.

Can you show a worked example?

Yes. Suppose you measure a desk at 2 metres and want it in feet.

1. Convert to metres (it is already in metres): metres = 2 × 1 = 2 m.
2. Divide by the foot factor: 2 ÷ 0.3048 = 6.56168 ft.

Now try the reverse. You read a height of 5 feet and want metres:

1. Convert to the base unit: metres = 5 × 0.3048 = 1.524 m.
2. To get centimetres, divide by 0.01: 1.524 ÷ 0.01 = 152.4 cm.

One more, mixing metric and imperial over a longer distance. A race is 10 kilometres and you want miles:

1. Convert to metres: metres = 10 × 1000 = 10,000 m.
2. Divide by the mile factor: 10,000 ÷ 1609.344 = 6.213712 mi.

These match the converter’s output exactly because it uses the same metre-based factors.

What are the most common length conversions?

These pairs come up constantly in everyday work, travel and DIY. The table below gives the exact factors the tool uses.

Conversion	Multiply by	Example
cm → inches	÷ 2.54	100 cm = 39.37008 in
inches → cm	× 2.54	12 in = 30.48 cm
feet → metres	× 0.3048	6 ft = 1.8288 m
metres → feet	÷ 0.3048	1 m = 3.28084 ft
km → miles	÷ 1.609344	5 km = 3.106856 mi
miles → km	× 1.609344	1 mi = 1.609344 km
yards → metres	× 0.9144	100 yd = 91.44 m
mm → inches	÷ 25.4	50 mm = 1.968504 in

For percentage-style scaling or splitting measurements into parts, the percentage calculator and ratio calculator pair well with these conversions.

When would I use a length converter?

A length converter is useful any time two systems of measurement meet:

• Travel and maps — turning road signs in kilometres into miles, or vice versa, when driving abroad.
• DIY and construction — reading a tape measure in inches but buying lumber or pipe sold in metres and centimetres. It pairs naturally with project tools like the fence calculator and roofing calculator.
• Fitness and running — converting a 5K or 10K race distance into miles for a pace plan.
• Crafts and sewing — switching fabric measured in yards into metres or centimetres.
• Science and homework — checking that a calculation lands in the right unit before submitting it.

You can find more unit tools, including weight converter and speed converter, on the converters category page.

What is the difference between metric and imperial length?

The metric system scales in clean powers of ten: 10 mm make a centimetre, 100 cm make a metre, and 1000 m make a kilometre. That makes mental conversions within metric simple — just shift the decimal point.

The imperial system uses mixed factors instead: 12 inches make a foot, 3 feet make a yard, and 1760 yards make a mile. Those uneven steps are why a dedicated converter helps. Because both systems are now anchored to the metre, the bridge between them is exact rather than approximate — there is no rounding baked into the definitions themselves.

What mistakes should I watch out for?

A few errors trip people up:

• Confusing similar abbreviations. A lower-case “m” is metres, “mm” is millimetres and “mi” is miles — mixing them changes results by a factor of a thousand or more.
• Rounding too early. If you round 1 m to “3.3 ft” and reuse that, errors compound. Keep full precision until the final step; the tool keeps 7 significant figures.
• Mixing feet and inches. A height of 5 ft 6 in is not 5.6 ft. Convert the inches first: 6 in = 0.5 ft, so it is 5.5 ft, or directly 1.6764 m.
• Assuming a “metric mile.” A mile is always 1609.344 m. The 1500 m track event is sometimes nicknamed the metric mile, but it is shorter than a true mile.

Are there any limitations?

This converter handles linear length and distance only — one dimension. It does not convert area (square metres, acres) or volume (litres, gallons), which use squared and cubed factors. It also assumes the modern international definitions; a few historical or survey units, such as the US survey foot, differ very slightly and are not included here. For everyday, engineering and educational use the results are exact to the displayed precision, but always sanity-check that the unit you selected matches the unit on your measuring device before relying on the figure.