Unit Converter

Bit

bit

Kbit

Mbit

Gbit

Tbit

Pbit

Kibit (1024)

Mibit (1024)

Gibit (1024)

Tibit (1024)

Pibit (1024)

Byte

Byte

KB

MB

GB

TB

PB

KiB (1024)

MiB (1024)

GiB (1024)

TiB (1024)

PiB (1024)

Differences between MiB and MB, KiB and KB:
1 KB (kilobyte) = 1000 bytes, 1 KiB (kibibyte) = 1024 bytes
1 MB (megabyte) = 1000000 bytes, 1 MiB (mebibyte) = 1048576 bytes

Hard drive manufacturers calculate in GB (decimal, i.e., 10 to the power of 3 = 1000, e.g., 1 MB = 1000 KB), whereas computers (operating systems) use GiB (binary, i.e., 2 to the power of 10, e.g., 1 MiB = 1024 KiB), but users generally understand 1 MB = 1024 KB. Therefore, for easier understanding in Chinese, translating MiB to MB is also acceptable.

Similarly, due to the different understandings of 1 MB size between hard drive manufacturers and users (where 1 MB = 1024 KB in actual computer terms), many 160 GB hard drives do not actually reach 160 GB, which explains why newly purchased hard drives often fall short of their labeled capacity.

In broadband networks, when ISPs mention 1M bandwidth, it refers to 1 Mbps (megabits per second). 'bps' stands for bits per second, used to measure data transfer rate. For example, telecom companies typically use bps. Since one byte equals 8 bits, our computer's storage units are in bytes, theoretically allowing downloading of 1x1024/8=128 KB/sec to the hard disk per second.
However, this is purely theoretical speed; in practice, about 12% of data is deducted for header information (Ethernet Header, IP Header, TCP Header, ATM Header, etc.), as well as various control signals. Thus, the maximum transfer speed should be around 112 KB/sec, and should not be misunderstood as "able to transfer 1M bytes of data per second." So never trust advertisements; in the writing of transfer units, B and b respectively represent Byte and bit, with a difference of 8 times.

b (bit, full name Binarydigit)
B (byte)
KB (kilobyte)
MB (megabyte)
GB (gigabyte)
TB (terabyte)
PB (petabyte)
EB (exabyte)
ZB (zettabyte)
YB (yottabyte)

International units of length

Kilometer (km)

Meter (m)

Decimeter (dm)

Centimeter (cm)

Millimeter (mm)

Decimillimeter (dmm)

Micrometer (um)

Nanometer (nm)

Imperial length units

Nautical Mile (nmi)

Fathom (fm)

Mile (mi)

Furlong (fur)

Yard (yd)

Foot (ft)

Inch (in)

Chinese length units of measurement

里

丈

尺

寸

分

厘

毫

International units of area

Square Kilometer (km²)

Square Meter (m²)

Square Decimeter (dm²)

Square Centimeter (cm²)

Square Millimeter (mm²)

Hectare (ha)

Imperial area units

Square Nautical Mile (nmi²)

Square Mile (mi²)

Acre (acre)

Square Rod (rd²)

Square Yard (yd²)

Square Foot (ft²)

Square Inch (in²)

Chinese area units of measurement

亩

分

厘

毫

International units of weight

Tonne (t)

Kilogram (kg)

Gram (g)

Milligram (mg)

Microgram (μg)

Imperial weight units (Avoirdupois)

Pound (lb)

Ounce (oz)

Stone (st)

Hundredweight (cwt)

Dram (dr)

Grain (gr)

Long ton (lt)

Imperial weight units (Troy weight)

Pound (lbt)

Ounce (ozt)

Grain

Pennyweight (dwt)

Chinese weight units of measurement

斤

两

钱

担

Metric system

Meters per second (m/s)

Kilometers per second (km/s)

Kilometers per hour (km/h)

Imperial/US System

Miles per Second (mile/s)

Miles per Hour (mile/h,mph)

Feet per Second (foot/s)

Maritime

Knot (kn)

Aviation

Mach (ma)

Others

Speed of Light (c)

First Cosmic Velocity

Second Cosmic Velocity

Third Cosmic Velocity

The fundamental unit of speed in the International System of Units (SI) is meters per second, with the international symbol "m/s" and the Chinese symbol "米/秒".

Mach (Ma) is a unit used to describe speed, representing the ratio of an object's speed in a fluid to the speed of sound in that medium. The unit is named after Ernst Mach, an Austrian physicist, in recognition of his contributions to fluid mechanics and supersonic research. Therefore, 1 Mach = 1 times the speed of sound.

1 knot = 1 nautical mile per hour = 1.852 kilometers per hour = 0.514444 meters per second.

Application of Speed Units in Various Fields

Knots (kn) and Mach (Ma) are commonly used in the aviation industry.
The maritime industry primarily uses knots (kn).
Road transportation uses kilometers per hour (km/h) or miles per hour (mph).
Meters per second (m/s) is widely used in scientific research.
For computer network transmission speed, bits per second (bps) or bytes per second (Bps) are commonly used.

International units of time

Year (year)

Month (month)

Day (d)

Hour (h)

Minute (min)

Second (s)

Millisecond (ms)

Week (week)

International units of temperature

Celsius (℃)

Fahrenheit (℉)

Kelvin (K)

Réaumur (°Re)

Rankine (°R)

Units of pressure

Pascal (Pa)

Hectopascal (hPa)

Kilopascal (kPa)

Megapascal (MPa)

Bar (bar)

Torr (torr)

Pound per square inch (psi)

Metric system

Milliwatt-hour (mW·h)

Watt-hour (W·h)

Kilowatt-hour (kW·h)

Megawatt-hour (MW·h)

Joule (J)

Kilojoule (kJ)

Imperial system

Metric Horsepower-hour (ps·h)

Horsepower-hour (hp·h)

British Thermal Unit (btu)

Foot-pound (ft·lb)

Others

Calorie (cal)

Kilocalorie (kcal)

Megacalorie (mcal)

Newton-meter (N·m)

Electronvolt (eV)

TNT Equivalent (ton TNT)

Basic Energy Units

Energy is a physical quantity in physics that represents the capacity to do work. The basic unit of energy in the International System of Units (SI) is the joule (J), defined as the work done when a force of 1 newton moves an object 1 meter in the direction of the force.

Basic Energy Units

1 kilojoule (kJ) = 1000 joules (J)
1 calorie (cal) = 4.184 joules (J)
1 kilocalorie (kcal) = 4184 joules (J)
1 kilowatt-hour (kWh) = 3,600,000 joules (J) = 3.6 megajoules (MJ)
1 British thermal unit (BTU) = 1055.06 joules (J)
1 electronvolt (eV) = 1.602176634×10⁻¹⁹ joules (J).

Heat Units

The calorie (cal) and the British thermal unit (BTU) are mainly used to measure heat. The food calorie (Cal, also called the large calorie) is actually the kilocalorie (kcal) and is commonly used on food nutrition labels. 1 kilocalorie (kcal) = 1 food calorie (Cal) = 4.184 kilojoules (kJ)
1 BTU can raise the temperature of 1 pound of water by 1 °F.

Electrical Energy Units

The watt-hour (Wh) and kilowatt-hour (kWh) are common units of electrical energy. One watt-hour is the energy consumed by a device with a power of 1 watt operating for 1 hour, equal to 3600 joules. The kilowatt-hour is the standard unit for household electricity billing; 1 kilowatt-hour (kWh) = 1000 watt-hours (Wh) = 3.6 megajoules (MJ).

Energy Industry Units

The tonne of oil equivalent (toe), tonne of coal equivalent (tce), and TNT equivalent are units for large-scale energy and explosive energy. 1 tonne of oil equivalent is about 41.868 gigajoules
1 tonne of TNT equivalent is about 4.184 gigajoules and is often used to express the power of nuclear weapons
The barrel of oil equivalent is used in the petroleum industry; 1 barrel of oil is about 6.1 gigajoules.

Energy Applications in Different Fields

Joule (J) and erg are commonly used in physics
Calorie (cal) and kilocalorie (kcal) are used in nutrition
Kilowatt-hour (kWh) and megawatt-hour (MWh) are used in the power sector
Electronvolt (eV) and its multiples are used in nuclear physics
Barrel of oil equivalent and tonne of oil equivalent are used in the energy industry
British thermal unit (BTU) is common in the HVAC industry.

Units of power

Watt (W)

Milliwatt (mW)

Kilowatt (kW)

Megawatt (MW)

Gigawatt (GW)

Joule per second (J/s)

Metric horsepower (ps)

Horsepower (hp)

British thermal unit (btu/s)

Foot-pound (ft·lb/s)

Power Units Basics

Power expresses how much work is done per unit time—in other words, the rate at which energy is converted. It is the work done (or energy transferred) per unit time. Simply put, the higher the power, the more work a device can complete in the same amount of time. For example, a 1 000 W microwave heats food faster than a 500 W one, a direct reflection of their power difference.

Below are real-life and industrial applications of various power units:

Small electronic devices – watts (W) and milliwatts (mW):

Phone standby: ≈ 0.1 W; while charging: 10-20 W
Bluetooth earpiece transmit power: ≈ 1-10 mW, compliant with radio regulations
Sensor consumption: a temp-humidity meter draws ≈ 0.5 mW; IoT devices typically operate in the mW range
LED bulbs: household units are usually 3-15 W

Household appliances – kilowatts (kW):

Air-conditioner cooling: 1 HP ≈ 0.735 kW; large 1.5 HP ≈ 1.1 kW
Electric kettle: ≈ 1.5-2 kW, a classic high-power domestic device
Microwave oven: 700 W-1.2 kW; cooking power directly affects heating speed
Induction cooker: 1-3 kW, adjustable to suit different cooking needs

Electric-vehicle charging – kilowatts (kW):

Home wall box: 7-22 kW, slow charging ideal for overnight
Fast charger: 50-350 kW, can add 80 % charge in ~30 min
Ultra-fast station: 250 kW and above

Large-scale energy facilities – megawatts (MW) & gigawatts (GW):

Nuclear reactor unit: ≈ 1 000 MW (1 GW), enough for roughly a million homes
Three Gorges Dam total capacity: 22.5 GW, the world’s largest hydro plant
PV solar farm: a 10 GW plant can supply ~4 million households annually
Wind turbine: single large offshore units reach 3-15 MW

Automotive engines – metric horsepower (PS) & mechanical horsepower (hp):

Family sedans: often rated in PS (e.g. 150 PS); European brands favour metric hp
US models: usually quote hp (e.g. 200 hp); imperial hp common in North America
Super-cars: 500-1 000 hp and beyond
Farm tractors: ≈ 50-100 hp, suited to field work

Refrigeration & air-conditioning – British thermal units per second (Btu/s):

Conversion: 1 ton of refrigeration ≈ 3.517 kW ≈ 12 000 Btu/h
Room AC capacity: labelled in Btu/h, e.g. 12 000 Btu/h ≈ 1 HP
Commercial chillers: large central systems can reach hundreds of tons

Mechanical engineering – foot-pounds per second (ft-lb/s):

Small engines: a lawnmower delivers ≈ 5-10 ft-lb/s
Industrial machinery: power measurement and calculation for various equipment
Torque conversion: used with horsepower to derive engine-performance parameters

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