Conversion Calculator

Convert length, weight, volume, temperature, area, speed, energy and more.

About Conversion Calculator

Length and mass conversions work by expressing the value in a base SI unit (meters or kilograms) and then converting to the target unit. Temperature uses exact Celsius/Fahrenheit/Kelvin formulas. Choose two units of the same category.

Formulas

Length and mass

result = value × (SI factor for source unit) ÷ (SI factor for target unit)

x: Input value
f_from: Metres-per-unit (length) or kg-per-unit (mass) for the source unit
f_to: Metres-per-unit (length) or kg-per-unit (mass) for the target unit

Temperature: °F ↔ °C

°C = (°F − 32) × 5/9 °F = °C × 9/5 + 32

Temperature: K ↔ °C

K = °C + 273.15 °C = K − 273.15

Worked example

With the default values below, Conversion Calculator returns Converted Value of 16.093440. Change any input above and every figure here is recalculated in your browser.

Inputs used

Valueaccepts -1,000,000,000,000–1,000,000,000,000: 10
Fromone of Meters (m), Kilometers (km), Centimeters (cm), Millimeters (mm), Miles (mi), Yards (yd), Feet (ft), Inches (in), Kilograms (kg), Grams (g), Milligrams (mg), Pounds (lb), Ounces (oz), Celsius (°C), Fahrenheit (°F), Kelvin (K): Miles (mi)
Toone of Meters (m), Kilometers (km), Centimeters (cm), Millimeters (mm), Miles (mi), Yards (yd), Feet (ft), Inches (in), Kilograms (kg), Grams (g), Milligrams (mg), Pounds (lb), Ounces (oz), Celsius (°C), Fahrenheit (°F), Kelvin (K): Kilometers (km)

Results

Converted Value: 16.093440

Step by step

1Convert mi to the SI base unit (meters)= 16,093.440000 m
2Convert meters to km= 16.093440 km

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

What is actually in here

Three families of units, and nothing else:

Length — m, km, cm, mm, mi, yd, ft, in
Mass — kg, g, mg, lb, oz
Temperature — C, F, K

Enter a value, choose a From unit and a To unit from the same family, and you get one converted figure. There is no volume, area, speed or data-size option. Cross-family requests are refused rather than guessed at, because miles and kilograms do not measure the same kind of thing.

Length and mass: one multiply, one divide

Both families route through an SI base unit — meters for length, kilograms for mass:

result = value × (factor for the From unit) ÷ (factor for the To unit)

The factors are exact internationally agreed definitions, not rounded approximations:

Unit	In base units
`in`	0.0254 m
`ft`	0.3048 m
`yd`	0.9144 m
`mi`	1609.344 m
`lb`	0.45359237 kg
`oz`	0.028349523125 kg

Everything imperial follows from one definition: 1 inch is exactly 2.54 cm. From there, 12 in = 1 ft, 3 ft = 1 yd, and 1760 yd = 1 mi.

The default conversion, step by step

The form opens on 10, from mi to km:

Into meters: 10 × 1609.344 = 16,093.44 m.
Out of meters: 1 km = 1000 m.
16,093.44 ÷ 1000 = 16.09344 km.

Mass works identically. 5 kg to lb is 5 ÷ 0.45359237 = 11.0231 lb, and 200 g to oz is 0.2 ÷ 0.028349523125 = 7.0548 oz.

Temperature needs its own formulas

The three temperature scales have different zero points, so a single multiplying factor would be wrong. These are used instead:

°F to °C: (°F − 32) × 5/9
°C to °F: °C × 9/5 + 32
°C to K: °C + 273.15; K to °C: K − 273.15

So 25 °C becomes 25 × 9/5 + 32 = 77 °F, or 25 + 273.15 = 298.15 K. A clinical 98.6 °F is (98.6 − 32) × 5/9 = 37 °C exactly. The Celsius and Fahrenheit scales cross at −40, the one temperature where both readings match.

Three things worth knowing

A temperature difference does not use the same formulas. A rise of 10 °C is a rise of 18 °F, not 50 °F, because the +32 offset applies to a reading, not to a gap.
Watch the single-letter options: m is meters and mg is milligrams, so they belong to different families and will not convert into each other.
Rounding happens only on display. 10 mi is 16.09344 km, so quoting 16.1 km has already discarded about 6 m.
Pounds here are a unit of mass, not pounds-force.

Converting distances for a drive? Pair this with the fuel cost calculator. If you need to scale a measurement by a percentage before converting it, work the change out in the percentage increase calculator.

Frequently Asked Questions

Can I convert miles to kilograms?

No — those measure different things (distance vs. mass). Pick two units of the same type: length with length, weight with weight, temperature with temperature.

How precise are the conversions?

They use exact internationally-defined factors (e.g. 1 inch = 0.0254 m), so results are accurate to the displayed decimal places.

Why does 1 kg convert to 2.2046 lb rather than a clean 2.2?

Because the pound is defined as exactly 0.45359237 kg, and 1 ÷ 0.45359237 = 2.2046226 lb. The familiar 2.2 is a mental shortcut that is about 0.2% low — on a 100 kg shipment that is roughly half a pound of error, which matters for freight or dosing.

Can I enter a height as 5 ft 9 in?

No — each conversion takes one value in one unit. Convert the compound figure yourself first: 5 ft 9 in is (5 × 12) + 9 = 69 in, and entering 69 with From `in` and To `cm` returns exactly 175.26 cm. The same trick works for pounds and ounces via a single total in `oz`.

Is stone or US ton in the mass list?

No. The mass options are only kg, g, mg, lb and oz. A stone is 14 lb, so enter 14 with From `lb` to see it as 6.35029 kg. A US short ton is 2000 lb, so enter 2000 the same way. Everything else has to be reduced to one of the five supported units.

Do mm and in convert directly, or do I have to go via cm?

Directly. Both are length units, so the converter routes through meters internally in one step: 25 mm is 0.025 m, and 0.025 ÷ 0.0254 = 0.98425 in. Chaining conversions by hand only adds rounding error, so always pick the true start and end units.