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Convert between units of length, weight, temperature and more as you type, with the formula shown. Your input isn't uploaded.

Quantity

Value

From

Your result will appear here.

39.37007874

Inches (in)

From: 100 cm
1 cm: 0.3937007874 in (rounded)
1 in: 2.54 cm (exact)
Rounding: Rounded to 10 significant digits

100 cm in every length unit
Unit	Value
Nanometres (nm)	1,000,000,000
Micrometres (µm)	1,000,000
Millimetres (mm)	1,000
Centimetres (cm)	100
Metres (m)	1
Kilometres (km)	0.001
Inches (in)	39.37007874
Feet (ft)	3.280839895
Yards (yd)	1.093613298
Miles (mi)	0.0006213711922
Nautical miles (nmi)	0.0005399568035

How it’s calculated

in = cm × 0.01 ÷ 0.0254

1 cm = 0.01 m exactly: the SI prefix centi (BIPM SI Brochure).
1 in = 0.0254 m exactly: the international inch (1959).
Results are rounded to 10 significant digits.

220.4622622

Pounds (lb)

From: 100 kg
1 kg: 2.204622622 lb (rounded)
1 lb: 0.45359237 kg (exact)
Rounding: Rounded to 10 significant digits

100 kg in every weight unit
Unit	Value
Milligrams (mg)	100,000,000
Grams (g)	100,000
Kilograms (kg)	100
Tonnes (t)	0.1
Ounces (oz)	3,527.396195
Pounds (lb)	220.4622622
Stone (st)	15.74730444
US tons (US ton)	0.1102311311
Imperial tons (imp ton)	0.09842065276

How it’s calculated

lb = kg × 1 ÷ 0.45359237

1 kg is the SI base unit of mass (BIPM SI Brochure).
1 lb = 0.45359237 kg exactly: the international pound (1959).
Results are rounded to 10 significant digits.
Weight here means mass: kilograms and pounds measure mass, not force.

212

Degrees Fahrenheit (°F)

From: 100 °C
Rounding: Exact

100 °C in every temperature unit
Unit	Value
Degrees Celsius (°C)	100
Degrees Fahrenheit (°F)	212
Kelvins (K)	373.15

How it’s calculated

°F = °C × 9/5 + 32

°C = K − 273.15 exactly: the Celsius scale (BIPM SI Brochure).
°F = K × 9/5 − 459.67 exactly: the Fahrenheit scale (NIST SP 811).
Results are rounded to 10 significant digits.
These are temperatures, not differences: a change of 1 °C is a change of 1.8 °F. Absolute zero is 0 K (−273.15 °C, −459.67 °F).

1,076.391042

Square feet (ft²)

From: 100 m²
1 m²: 10.76391042 ft² (rounded)
1 ft²: 0.09290304 m² (exact)
Rounding: Rounded to 10 significant digits

100 m² in every area unit
Unit	Value
Square millimetres (mm²)	100,000,000
Square centimetres (cm²)	1,000,000
Square metres (m²)	100
Hectares (ha)	0.01
Square kilometres (km²)	0.0001
Square inches (in²)	155,000.31
Square feet (ft²)	1,076.391042
Square yards (yd²)	119.5990046
Acres (ac)	0.02471053815
Square miles (mi²)	0.00003861021585

How it’s calculated

ft² = m² × 1 ÷ 0.09290304

1 m² is the SI unit of area (BIPM SI Brochure).
1 ft² = 0.09290304 m² exactly: the square of the international foot (1959).
Results are rounded to 10 significant digits.
The acre is the international acre, 4,840 square yards.

26.41720524

US gallons (US gal)

From: 100 L
1 L: 0.2641720524 US gal (rounded)
1 US gal: 3.785411784 L (exact)
Rounding: Rounded to 10 significant digits

100 L in every volume unit
Unit	Value
Millilitres (mL)	100,000
Litres (L)	100
Cubic centimetres (cm³)	100,000
Cubic metres (m³)	0.1
Cubic inches (in³)	6,102.374409
Cubic feet (ft³)	3.531466672
US teaspoons (US tsp)	20,288.41362
US tablespoons (US tbsp)	6,762.80454
US fluid ounces (US fl oz)	3,381.40227
US cups (US cup)	422.6752838
US pints (US pt)	211.3376419
US quarts (US qt)	105.6688209
US gallons (US gal)	26.41720524
Imperial fluid ounces (imp fl oz)	3,519.507973
Imperial pints (imp pt)	175.9753986
Imperial gallons (imp gal)	21.99692483

How it’s calculated

US gal = L × 0.001 ÷ 0.003785411784

1 L = 0.001 m³ exactly: one cubic decimetre (BIPM SI Brochure).
1 US gal = 0.003785411784 m³ exactly: 231 cubic inches (NIST SP 811).
Results are rounded to 10 significant digits.
US and imperial units differ: a US gallon is 3.785411784 L, an imperial gallon 4.54609 L.

62.13711922

Miles per hour (mph)

From: 100 km/h
1 km/h: 0.6213711922 mph (rounded)
1 mph: 1.609344 km/h (exact)
Rounding: Rounded to 10 significant digits

100 km/h in every speed unit
Unit	Value
Metres per second (m/s)	27.77777778
Kilometres per hour (km/h)	100
Miles per hour (mph)	62.13711922
Knots (kn)	53.99568035
Feet per second (ft/s)	91.13444153

How it’s calculated

mph = km/h × (1,000 ÷ 3,600) ÷ 0.44704

1 km/h = 1,000 m ÷ 3,600 s exactly: one kilometre per hour (BIPM SI Brochure).
1 mph = 0.44704 m/s exactly: one international mile per hour (1959).
Results are rounded to 10 significant digits.

93.13225746

Gibibytes (GiB)

From: 100 GB
1 GB: 0.9313225746 GiB (rounded)
1 GiB: 1.073741824 GB (exact)
Rounding: Rounded to 10 significant digits

100 GB in every data size unit
Unit	Value
Bits (bit)	800,000,000,000
Bytes (B)	100,000,000,000
Kilobytes (kB)	100,000,000
Megabytes (MB)	100,000
Gigabytes (GB)	100
Terabytes (TB)	0.1
Petabytes (PB)	0.0001
Kibibytes (KiB)	97,656,250
Mebibytes (MiB)	95,367.43164
Gibibytes (GiB)	93.13225746
Tebibytes (TiB)	0.09094947018
Pebibytes (PiB)	0.00008881784197

How it’s calculated

GiB = GB × 1,000,000,000 ÷ 1,073,741,824

1 GB = 1,000,000,000 B exactly: the SI prefix giga (IEC 80000-13).
1 GiB = 1,073,741,824 B exactly: the binary prefix gibi, 2³⁰ (IEC 80000-13).
Results are rounded to 10 significant digits.
kB, MB, GB, TB and PB step by 1,000; KiB, MiB, GiB, TiB and PiB by 1,024.

1.666666667

Hours (h)

From: 100 min
1 min: 0.01666666667 h (rounded)
1 h: 60 min (exact)
Rounding: Rounded to 10 significant digits

100 min in every time unit
Unit	Value
Milliseconds (ms)	6,000,000
Seconds (s)	6,000
Minutes (min)	100
Hours (h)	1.666666667
Days (d)	0.06944444444
Weeks (wk)	0.009920634921
Months (month)	0.002281542323
Years (yr)	0.0001901285269

How it’s calculated

h = min × 60 ÷ 3,600

1 min = 60 s exactly (BIPM SI Brochure).
1 h = 3,600 s exactly (BIPM SI Brochure).
Results are rounded to 10 significant digits.
A year here is 365.25 days and a month a twelfth of it; calendar months and years vary.

14.50377377

Pounds per square inch (psi)

From: 100 kPa
1 kPa: 0.1450377377 psi (rounded)
1 psi: 6.894757293 kPa (rounded)
Rounding: Rounded to 10 significant digits

100 kPa in every pressure unit
Unit	Value
Pascals (Pa)	100,000
Hectopascals (hPa)	1,000
Kilopascals (kPa)	100
Megapascals (MPa)	0.1
Bars (bar)	1
Atmospheres (atm)	0.9869232667
Pounds per square inch (psi)	14.50377377
Millimetres of mercury (mmHg)	750.0615758
Inches of mercury (inHg)	29.5299833
Torr (Torr)	750.0616827

How it’s calculated

psi = kPa × 1,000 ÷ (4.4482216152605 ÷ 0.00064516)

1 kPa = 1,000 Pa exactly: the SI prefix kilo (BIPM SI Brochure).
1 psi = 4.4482216152605 N ÷ 0.00064516 m² exactly: one pound-force (0.45359237 kg × 9.80665 m/s²) per square inch (NIST SP 811).
Results are rounded to 10 significant digits.
mmHg and inHg are the conventional values used for blood pressure and weather.

418.4

Kilojoules (kJ)

From: 100 kcal
1 kcal: 4.184 kJ (exact)
1 kJ: 0.2390057361 kcal (rounded)
Rounding: Exact

100 kcal in every energy unit
Unit	Value
Joules (J)	418,400
Kilojoules (kJ)	418.4
Megajoules (MJ)	0.4184
Watt-hours (Wh)	116.2222222
Kilowatt-hours (kWh)	0.1162222222
Calories (cal)	100,000
Kilocalories (kcal)	100
British thermal units (BTU)	396.5666831
Electronvolts (eV)	2.611447397 × 10²⁴
Foot-pounds (ft·lbf)	308,596.0033

How it’s calculated

kJ = kcal × 4,184 ÷ 1,000

1 kcal = 4,184 J exactly: 1,000 thermochemical calories (NIST SP 811).
1 kJ = 1,000 J exactly: the SI prefix kilo (BIPM SI Brochure).
Results are rounded to 10 significant digits.
cal is the thermochemical calorie (4.184 J); the Calorie on food labels is the kcal.

What it does

The unit converter changes a value from one unit to another. It covers 10 quantities with 94 units in all: length, weight, temperature, area, volume, speed, data size, time, pressure and energy.

The answer updates as you type. Under it you see your value with its unit, what one unit of each is in the other (for every quantity but temperature), how it’s calculated, and a table of your value in every unit of the quantity.

How to use it

Under Quantity, choose what you’re converting, such as Length or Temperature. Each quantity starts on a common pair, such as centimetres to inches or degrees Celsius to degrees Fahrenheit.
Type your number in Value.
Choose the From and To units. They can be the same unit; the answer is then your value, to 10 significant digits.
Select Copy value to put the answer on your clipboard, or Copy table for your value in every unit.

The converter remembers your quantity, value and units on this device, so they’re there the next time you open the page.

How sizes are defined

Each unit except °C and °F is a fixed multiple of one unit of its quantity: the metre, kilogram, kelvin, square metre, cubic metre, metre per second, byte, second, pascal and joule. The sizes come from their definitions: the BIPM SI Brochure for SI units and the units accepted for use with them, NIST SP 811 for US units and other units outside the SI such as the bar, atmosphere, calorie and degree Fahrenheit, the international yard and pound agreement of 1959 for inches, feet, yards, miles, ounces and pounds, the UK Weights and Measures Act 1985 for imperial units, IEC 80000-13 for data sizes and the IAU for the Julian year.

Inches and pounds: an inch is 25.4 mm and a pound 0.45359237 kg exactly, by the international yard and pound agreement of 1959. Feet, yards, miles, ounces and stone follow from them.
US and imperial: these are separate units with separate names. A US gallon is 3.785411784 L and an imperial gallon 4.54609 L. US cups, pints, quarts and fluid ounces are fractions of the US gallon, and imperial pints and fluid ounces fractions of the imperial gallon. A US ton is 2,000 lb and an imperial ton 2,240 lb.
Data sizes: kB, MB, GB, TB and PB are SI sizes that step by 1,000; KiB, MiB, GiB, TiB and PiB are binary sizes that step by 1,024. A bit is 1/8 of a byte.
Time: a year is 365.25 days, the Julian year, and a month is 1/12 of that, 30.4375 days. Calendar months and years vary.
Pressure and energy: psi uses the pound-force (0.45359237 kg × 9.80665 m/s²), and mmHg and inHg are the conventional values. cal is the thermochemical calorie, 4.184 J; the Calorie on food labels is the kcal, 4,184 J.

Temperatures

Temperature scales start at different points, so they convert by formula rather than by one factor:

°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
°C = K − 273.15
K = (°F + 459.67) × 5/9
°F = K × 9/5 − 459.67

The lowest value accepted is absolute zero: −273.15 °C, −459.67 °F or 0 K. These convert temperatures, not differences: a change of 1 °C is a change of 1.8 °F.

How it’s calculated

For every quantity but temperature, the converter works out To = From × size of From ÷ size of To, with both sizes in that one unit of the quantity. For 100 cm to inches, that is in = cm × 0.01 ÷ 0.0254, so 100 cm is 39.37007874 in.

Your value and each size are worked as exact fractions, so only the shown answer is rounded: 1 imperial ton is exactly 2,240 lb, and the Rounding row says Exact.

Rounding

Answers show 10 significant digits, rounded half away from zero, with trailing zeros dropped, so 100 kg is 220.4622622 lb. The Rounding row says Exact when the answer has no more digits than that, or Rounded to 10 significant digits when it has more. The one-unit rows are marked (exact) or (rounded) the same way.

Answers of 10¹⁵ or more, and answers other than 0 smaller than 0.000001 in size, are shown with a power of ten: 1 eV is 1.602176634 × 10⁻¹⁹ J.

Good to know

Values from 0 to 1,000,000,000,000; temperatures from absolute zero. A value outside that range is marked at Value, with the range in the From unit.
Weight here means mass: kilograms and pounds measure mass, not force.

Privacy

Your input isn’t uploaded: the conversion runs on your device. Only your quantity, value and units are kept, in this browser’s storage, so the page can show them again.

Frequently asked questions

What is the difference between a US gallon and an imperial gallon?

They are different units. A US gallon is 231 cubic inches, 3.785411784 L exactly, and an imperial gallon is 4.54609 L exactly, so 100 US gallons is 83.26741846 imperial gallons. The converter lists US and imperial units separately, each with its own name: choose the one your recipe, label or meter uses.

Is a kilobyte 1,000 or 1,024 bytes?

Here a kilobyte (kB) is 1,000 bytes, as the SI prefix kilo means, and a kibibyte (KiB) is 1,024 bytes (IEC 80000-13). kB, MB, GB, TB and PB step by 1,000; KiB, MiB, GiB, TiB and PiB by 1,024. That is why 100 GB shows as 93.13225746 GiB.

Why does 1 cm to inches show as rounded?

An inch is 2.54 cm exactly, so 1 cm is 1 ÷ 2.54 inches, a decimal whose digits repeat without end. The converter shows 10 significant digits, 0.3937007874, and marks it rounded; the row for 1 in shows 2.54 cm and is marked exact.

How do temperatures convert?

By formula, not by one factor, because the scales start at different points: °F = °C × 9/5 + 32 and K = °C + 273.15. So 100 °C is 212 °F and 373.15 K. The lowest value accepted is absolute zero: −273.15 °C, −459.67 °F or 0 K.

Is what I type uploaded?

No. Your input isn't uploaded: the conversion runs on your device. Your quantity, value and units are kept in this browser's storage, so the page can show them again.

Unit converter

What it does

How to use it

How sizes are defined

Temperatures

How it’s calculated

Rounding

Good to know

Privacy

Frequently asked questions

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