Reference tables

UnitCloud is a local measurement lab for everyday work, engineering, IT, energy, mobility and design. Every conversion shows result, formula, base unit, rounding and the common mistake.

Length

Unit	Symbol	Formula
Nanometre	nm	1 nm = 0.000000001 m
Micrometre	µm	1 µm = 0.000001 m
Millimetre	mm	1 mm = 0.001 m
Centimetre	cm	1 cm = 0.01 m
Metre	m	base
Kilometre	km	1 km = 1000 m
Inch	in	1 in = 0.0254 m
Foot	ft	1 ft = 0.3048 m
Yard	yd	1 yd = 0.9144 m
Mile	mi	1 mi = 1609.344 m
Nautical mile	nmi	1 nmi = 1852 m
Light-second	ls	1 ls = 299792458 m
Astronomical unit	AE	1 AE = 149597870700 m
Light-year	Lj	1 Lj = 9460730472580800 m
Parsec	pc	1 pc = 3.0856775814913673e16 m

Area

Unit	Symbol	Formula
Square millimetre	mm²	1 mm² = 0.000001 m²
Square centimetre	cm²	1 cm² = 0.0001 m²
Square metre	m²	base
Square kilometre	km²	1 km² = 1,000,000 m²
Hectare	ha	1 ha = 10,000 m²
Acre	acre	1 acre = 4046.8564224 m²
Square foot	ft²	1 ft² = 0.09290304 m²
Square inch	in²	1 in² = 0.00064516 m²
Are	a	1 a = 100 m²
Square yard	yd²	1 yd² = 0.83612736 m²
Square mile	mi²	1 mi² = 2589988.110336 m²

Volume

Unit	Symbol	Formula
Millilitre	ml	1 ml = 0.001 l
Centilitre	cl	1 cl = 0.01 l
Decilitre	dl	1 dl = 0.1 l
Litre	l	base
Cubic metre	m³	1 m³ = 1000 l
Teaspoon	tsp	US tsp
Tablespoon	tbsp	US tbsp
Cup	cup	US cup
Fluid ounce	fl oz	US fl oz
US gallon	gal	1 US gal = 3.785411784 l
Imperial gallon	imp gal	1 imp gal = 4.54609 l
Hectolitre	hl	1 hl = 100 l
Oil barrel	bbl	1 bbl = 158.987294928 l

Mass

Unit	Symbol	Formula
Microgram	µg	1 µg = 0.000001 g
Milligram	mg	1 mg = 0.001 g
Gram	g	base
Kilogram	kg	1 kg = 1000 g
Tonne	t	1 t = 1000 kg
Ounce	oz	1 oz = 28.349523125 g
Pound	lb	1 lb = 453.59237 g
Stone	st	1 st = 14 lb
Carat	ct	1 ct = 0.2 g

Temperature

Unit	Symbol	Formula
Celsius	°C	base
Fahrenheit	°F	°F = °C × 9/5 + 32
Kelvin	K	K = °C + 273.15
Rankine	°R	°R = (°C + 273.15) × 9/5

Data

Unit	Symbol	Formula
Bit	bit	8 bit = 1 Byte
Byte	B	base
Kilobyte	KB	1 KB = 1000 B
Megabyte	MB	1 MB = 1,000,000 B
Gigabyte	GB	1 GB = 1,000,000,000 B
Terabyte	TB	1 TB = 10¹² B
Kibibyte	KiB	1 KiB = 1024 B
Mebibyte	MiB	1 MiB = 1024 KiB
Gibibyte	GiB	1 GiB = 1024 MiB
Tebibyte	TiB	1 TiB = 1024 GiB
Petabyte	PB	1 PB = 1000000000000000 Byte
Pebibyte	PiB	1 PiB = 1125899906842624 Byte

Speed

Unit	Symbol	Formula
Metres per second	m/s	base
Kilometres per hour	km/h	1 km/h = 0.277777... m/s
Miles per hour	mph	1 mph = 0.44704 m/s
Knot	kn	1 kn = 0.514444... m/s
Feet per second	ft/s	1 ft/s = 0.3048 m/s
Speed of light	c	1 c = 299792458 m/s

Energy

Unit	Symbol	Formula
Joule	J	base
Kilojoule	kJ	1 kJ = 1000 J
Watt-hour	Wh	1 Wh = 3600 J
Kilowatt-hour	kWh	1 kWh = 3,600,000 J
Calorie	cal	1 cal = 4.184 J
Kilocalorie	kcal	1 kcal = 4184 J
British thermal unit	BTU	1 BTU ≈ 1055.05585 J
Electronvolt	eV	1 eV = 1.602176634e-19 J
Megawatt hour	MWh	1 MWh = 3600000000 J
Gigawatt hour	GWh	1 GWh = 3600000000000 J

Power

Unit	Symbol	Formula
Watt	W	base
Kilowatt	kW	1 kW = 1000 W
Megawatt	MW	1 MW = 1,000,000 W
Metric horsepower	PS	1 PS = 735.49875 W
Mechanical horsepower	hp	1 hp ≈ 745.699872 W
BTU per hour	BTU/h	1 BTU/h ≈ 0.293071 W

Pressure

Unit	Symbol	Formula
Pascal	Pa	base
Kilopascal	kPa	1 kPa = 1000 Pa
Megapascal	MPa	1 MPa = 1,000,000 Pa
bar	bar	1 bar = 100,000 Pa
Millibar	mbar	1 mbar = 100 Pa
psi	psi	1 psi ≈ 6894.757 Pa
Atmosphere	atm	1 atm = 101,325 Pa
Torr	Torr	1 Torr ≈ 133.322 Pa
Hectopascal	hPa	1 hPa = 100 Pa
Millimetre of mercury	mmHg	1 mmHg = 133.322387415 Pa
Inch of mercury	inHg	1 inHg = 3386.389 Pa

Density

Unit	Symbol	Formula
Kilogram per cubic metre	kg/m³	base
Gram per cubic centimetre	g/cm³	1 g/cm³ = 1000 kg/m³
Gram per litre	g/l	1 g/l = 1 kg/m³
Pound per cubic foot	lb/ft³	1 lb/ft³ ≈ 16.0185 kg/m³

Time

Unit	Symbol	Formula
Millisecond	ms	1 ms = 0.001 s
Second	s	base
Minute	min	1 min = 60 s
Hour	h	1 h = 3600 s
Day	d	1 d = 86400 s
Week	week	1 week = 7 d
Year, 365 days	year	365 d

Angle

Unit	Symbol	Formula
Radian	rad	base
Degree	°	1° = π/180 rad
Gradian	gon	1 gon = π/200 rad
Turn	turn	1 turn = 2π rad
Arcminute	′	1′ = 1/60°
Arcsecond	″	1″ = 1/3600°

Force

Unit	Symbol	Formula
Newton	N	base
Kilonewton	kN	1 kN = 1000 N
Meganewton	MN	1 MN = 1,000,000 N
Pound-force	lbf	1 lbf ≈ 4.44822 N
Kilogram-force	kgf	1 kgf = 9.80665 N

Torque

Unit	Symbol	Formula
Newton metre	N·m	base
Pound-foot	lb·ft	1 lb·ft ≈ 1.35582 N·m
Pound-inch	lb·in	1 lb·in ≈ 0.112985 N·m
Kilogram-force metre	kgf·m	1 kgf·m = 9.80665 N·m

Fuel economy

Unit	Symbol	Formula
Litres per 100 kilometres	l/100 km	base
Kilometres per litre	km/l	km/l = 100 / l/100 km
Miles per US gallon	mpg US	mpg US = 235.214583 / l/100 km
Miles per imperial gallon	mpg imp	mpg imp = 282.480936 / l/100 km

Typography

Unit	Symbol	Formula
Point	pt	base
Pica	pc	1 pc = 12 pt
Inch	in	1 in = 72 pt
Millimetre	mm	1 mm ≈ 2.83465 pt
Centimetre	cm	1 cm ≈ 28.3465 pt
CSS pixel	px	1 px = 0.75 pt at 96 dpi

Image resolution

Unit	Symbol	Formula
Pixel	px	base
Kilopixel	kpx	1 kpx = 1000 px
Megapixel	MP	1 MP = 1,000,000 px
Gigapixel	GP	1 GP = 1,000,000,000 px

Frequency

Unit	Symbol	Formula
Hertz	Hz	base
Kilohertz	kHz	1 kHz = 1000 Hz
Megahertz	MHz	1 MHz = 1,000,000 Hz
Gigahertz	GHz	1 GHz = 1,000,000,000 Hz
Revolutions per minute	rpm	1 rpm = 1/60 Hz
Beats per minute	bpm	1 bpm = 1/60 Hz

SI prefixes: the official table

The International System of Units defines exactly 24 prefixes, standing for powers of ten from quecto (10⁻³⁰) to quetta (10³⁰), attached to the unit symbol without a space.

Paper sizes according to ISO 216

The A series is built by halving the next larger sheet, so the aspect ratio stays constant at 1 : √2 from A0 down to A10. The figures below are the trimmed finished sizes in millimetres.

Bandwidth: Mbit/s in MB/s

Providers advertise Mbit/s, download tools display MB/s. The factor between them is eight, because one byte holds eight bits. This table shows the same line in both notations.

Data volumes: binary versus decimal

Drive manufacturers count in decimal (GB = 10⁹ bytes), operating systems count in binary (GiB = 2³⁰ bytes). That is why a “1 TB drive” shows less than 1 TB in the system. The deviation grows with every step.

Cooking measures: cup, tablespoon, teaspoon

Recipes from English-speaking countries measure by volume, German recipes often by weight. This table shows the customary US cooking measures in millilitres.

Energy units compared

Electricity tariffs use kilowatt hours, physics uses joules, heating technology uses kilocalories or BTU. This table shows the same amount of energy in every unit of the family.

Astronomical distances

Astronomical unit, light-year and parsec all describe a length, just in very different steps. The table shows one unit of each in all the others.

Battery capacity: mAh and Wh

Milliampere hours measure charge, watt hours measure energy. They are linked only through voltage: Wh = Ah × volts. That is why two batteries with identical mAh are not automatically equal in size.

Flow rate: m³/h, l/min and l/s

Heating and plumbing work in cubic metres per hour, pumps and fittings often in litres per minute. This table shows the same flow rate in every notation.

Tyre pressure: bar, psi and kPa

Vehicle manuals state bar, inflators often show psi or kPa. This table converts the same pressure reading into each unit — without recommending a value for any specific vehicle.

Torque: N·m, lb·ft and kgf·m

Workshop manuals and datasheets switch between newton metres, pound-feet and kilogram-force metres. This table shows the same torques in all three notations.

Mass: kilograms, grams, pounds and ounces

Kilograms and grams are metric, pounds and ounces belong to the imperial system. The table shows the same mass in all four units; one pound is exactly 453.59237 grams.

Area: square metres, hectares and acres

Land is measured in square metres, hectares or acres. The table shows the same area in every unit; one hectare is exactly 10,000 square metres.

Temperature: Celsius, Fahrenheit and Kelvin

Temperature is the one quantity here with an offset: Celsius and Fahrenheit are shifted against each other and Kelvin starts at absolute zero, so these conversions add rather than only multiply.

Speed: km/h, m/s, mph and knots

Road traffic uses km/h, physics uses m/s, shipping and aviation use knots. The table shows the same speed in all four units.

Power: watts, kilowatts, PS and hp

Engine power is quoted in kW, PS or hp. PS and hp are not the same unit: metric horsepower and mechanical horsepower differ by about 1.4 percent.

Density: kg/m³, g/cm³ and lb/ft³

Density is mass per volume. Engineering uses kg/m³, laboratory values often g/cm³, and imperial tables lb/ft³. The table shows the same density in every unit.

Time: seconds, minutes, hours and days

The second is the SI base unit of time. Minute, hour and day are legally defined multiples of it; the week is pure convention.

Angle: degrees, radians and gon

Mathematics and physics work in radians, everyday use and engineering in degrees, surveying in gon. The table shows the same angle in every unit.

Force: newtons, kilopond and pound-force

Force is measured in newtons. Kilopond and pound-force are older units tied to standard gravity and are still used in engineering and sport.

Fuel consumption: l/100 km, mpg US and mpg imp

Europe states consumption in litres per 100 kilometres, English-speaking countries in miles per gallon. The two are inverse to each other: a lower figure in l/100 km corresponds to a higher figure in mpg.

Typography: points, picas, millimetres and pixels

Print and web use different points. A DTP point is 1/72 inch and a CSS pixel is 1/96 inch. The table shows the same type size in every unit.

Frequency: hertz, kilohertz, megahertz and rpm

Hertz states cycles per second. Rotational speed is often given in revolutions per minute instead; the relation is fixed: 1 Hz = 60 rpm. The table spans mains frequency up to a CPU clock.

Acceleration: m/s², g and ft/s²

Acceleration is the change of speed per time. Engineering often states it as a multiple of standard gravity g rather than in m/s².

Image resolution: pixels, kilopixels and megapixels

Cameras and displays are quoted in megapixels, image files in pixels. The table shows the same resolution in every unit; one megapixel is exactly one million pixels.