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Unit Tools 405 Tools Available

Free Online Length, Weight, Temperature, Data, Speed & Cooking Unit Converter Tools

Convert any unit in one place. Change cm to inches, kg to pounds, Celsius to Fahrenheit, MB to GB, km/h to mph, cups to millilitres and hundreds more across twenty categories. Answers appear as you type, each one shows the exact factor it used, and everything keeps working offline.

20 Converters Answers As You Type Exact Where Exact Exists Works Offline
Free Online Length, Weight, Temperature, Data, Speed & Cooking Unit Converter Tools
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Choose a Converter

Each kind of unit has its own page, and its own list of units.

Popular New

Length Converter

An inch is exactly 2.54 cm, not roughly

Convert cm to inches, feet to metres, mm to cm and km to miles. Exact factors and answers as you type. Free converter.

  • 11 units: nanometres up to kilometres, plus inches, feet, yards, miles and nautical miles
  • Since 1959 the inch, foot, yard and mile are all defined from the metre, so these factors are fixed
  • That means the answers carry no error of their own, and the only rounding is the one you choose
  • cm to inches, feet to metres and mm to cm ready as one-tap pairs
Convert Length
Popular New

Weight Converter

A pound is exactly 0.45359237 kg

Convert kg to lbs, grams to ounces, stones and tonnes. Exact factors, instant answers and it works offline. Free tool.

  • 9 units: milligrams to tonnes, plus ounces, pounds, stones and both US and UK tons
  • The pound and ounce have been defined from the kilogram since 1959, so nothing here is an estimate
  • US short ton and UK long ton kept apart, because they are not the same weight
  • kg to lbs and stones to kg saved as pairs you can reopen
Convert Weight
Popular New

Temperature Converter

The one family that does not simply scale

Convert Celsius to Fahrenheit and Kelvin, both ways, with the formula shown. Instant answers, free and works offline.

  • Celsius, Fahrenheit and Kelvin, in every direction
  • 20 °C is not twice 10 °C, because each scale puts its zero somewhere else
  • Converting shifts as well as stretches, so temperatures below zero come out right
  • The only converter here that never just multiplies, and the page explains why
Convert Temperature
New

Area Converter

Including marla and kanal, with the standard named

Convert square feet, square metres, acres, hectares, marla and kanal. Regional land units stated clearly. Free converter.

  • 12 units: mm² through km², plus square feet, yards, acres, hectares, marla and kanal
  • Marla changes from place to place, so this one states which it uses: 272.25 ft², 20 to a kanal
  • Older land records sometimes use a 225 ft² marla, and the page tells you to check before trusting a figure
  • Square feet to marla and marla to square yards ready to go
Convert Area
New

Volume Converter

US and imperial are about 20% apart

Convert litres, gallons, millilitres, cups and pints. US and imperial units kept separate so the answer is right. Free.

  • 17 units: millilitres and litres, cubic measures, and both US and imperial liquid units
  • An imperial gallon is 4.54609 L and a US gallon 3.785412 L, which is not a rounding difference
  • Pints and fluid ounces differ too, so every unit says which family it belongs to
  • No guessing which gallon a recipe or a spec sheet meant
Convert Volume
New

Speed Converter

Mach is not a fixed speed, and it says so

Convert km/h to mph, m/s, knots and Mach instantly. Exact factors shown and it keeps working offline. Free converter.

  • 6 units: metres per second, km/h, mph, feet per second, knots and Mach
  • The speed of sound moves with air temperature, so Mach 1 is not one number
  • This uses dry air at sea level and 15 °C, about 340.29 m/s, and names that assumption
  • Higher up the air is colder and Mach 1 is slower, which is why aircraft speeds are quoted that way
Convert Speed

Time Converter

Months and years here are averages

Convert seconds, minutes, hours, days, weeks and years, down to milliseconds. Average month length stated clearly. Free.

  • 8 units: milliseconds, seconds, minutes, hours, days, weeks, months and years
  • A month is taken as 30.44 days and a year as 365.25, which is fine for rough spans
  • A real month is 28 to 31 days and a real year is 365 or 366, so calendar dates need a date calculator instead
  • The page says this plainly rather than letting the answer look more precise than it is
Convert Time

Data Storage Converter

Why a 1 TB drive shows up as 931 GB

Convert MB to GB, KB to MB and TB, in both decimal and binary units. See why a 1 TB drive shows as 931 GB. Free tool.

  • 12 units: bits and bytes through petabytes, in both the 1,000 and the 1,024 family
  • A kilobyte is 1,000 bytes and a kibibyte is 1,024, and that single mismatch is the whole story
  • Drive makers count one way, Windows displays the other and still writes GB
  • Nothing is missing from your drive, and this converter shows exactly where the difference goes
Convert Data Size

Energy Converter

The calorie on a food label is a kilocalorie

Convert joules, calories, kWh, BTU and watt hours. Food and scientific calories kept separate. Free online converter.

  • 8 units: joules, kilojoules, calories, kilocalories, watt hours, kWh, BTU and electronvolts
  • One food Calorie is 1,000 small calories, which is 4,184 joules
  • The two are kept apart, so a nutrition figure never lands a thousand times off
  • If you are reading a label, the unit you want is kcal, and the page points that out
Convert Energy

Power Converter

There is more than one horsepower

Convert watts, kilowatts, horsepower and BTU per hour. Metric and mechanical horsepower kept apart. Free converter.

  • 6 units: watts, kilowatts, megawatts, both horsepowers and BTU per hour
  • Mechanical horsepower is about 745.7 W; metric horsepower, written PS, is about 735.5 W
  • That is roughly 1.4% apart, which is enough to misquote an engine
  • Both are separate units here, so a figure converts the way it was originally quoted
Convert Power

Pressure Converter

1 bar is 14.5 psi, near enough for tyres

Convert psi to bar, kPa, atmospheres and mmHg. Handy for tyre pressure and gauges. Instant answers, free converter.

  • 9 units: pascal, kPa, MPa, bar, millibar, psi, atmospheres, torr and mmHg
  • The exact figure is 14.5038 psi to the bar, and for tyre pressure that rounding never matters
  • Bar is not an SI unit but survives because it sits close to normal air pressure at sea level
  • A tyre pressure chart on the page for the numbers people actually look up
Convert Pressure

Number System Converter

One crore is ten million, and the zeros are counted

Convert binary, decimal, hexadecimal and octal both ways, with the working shown and invalid digits caught. Free tool.

  • 9 scales: thousand, lakh, million, crore, billion, arab, kharab and trillion
  • South Asia groups digits in twos after the first thousand, the West groups them in threes
  • That one difference is where the zeros get lost, so this counts them out for you
  • A lakh is 100,000, a crore is 100 lakh, and an arab is 100 crore, which lands exactly on a billion
Convert Lakh and Crore

Frequency Converter

RPM belongs on the same scale as hertz

Convert Hz, kHz, MHz, GHz and RPM instantly. Useful for radio, audio and motor ratings. Free online frequency converter.

  • 5 units: hertz, kilohertz, megahertz, gigahertz and revolutions per minute
  • One revolution per minute is one cycle every 60 seconds, so 60 RPM is exactly 1 Hz
  • That puts engine and motor speeds next to radio and electrical frequencies
  • Handy the moment you need to compare the two, which most frequency tools will not do
Convert Frequency

Angle Converter

Why a radian never looks like a round number

Convert degrees to radians and back, with the answer as a multiple of pi, plus gradians, turns and arcminutes. Free.

  • 6 units: degrees, radians, gradians, arcminutes, arcseconds and full turns
  • A full turn is 360 degrees or 2π radians, so the two scales do not line up neatly
  • One radian is about 57.30 degrees, and the page explains where that comes from
  • A radian ties the angle to the length of the arc it cuts, which is why maths prefers it
Convert Angles

Force Converter

Kilogram-force is a force, not a mass

Convert newtons, kilogram-force, pounds-force, dynes and kips, with the gravity value used shown. Free converter.

  • 5 units: newtons, kilonewtons, dynes, pound-force and kilogram-force
  • One kilogram-force is what a kilogram weighs under standard gravity: exactly 9.80665 newtons
  • It is convenient and not an SI unit, so engineering work converts it to newtons
  • That one unit is also the bridge between the kilogram you weigh and the force you apply
Convert Force

Voltage Converter

Clean powers of ten, so nothing is lost

Convert volts, millivolts, kilovolts and microvolts instantly, with exact factors shown. Free online voltage converter.

  • 5 units: microvolts, millivolts, volts, kilovolts and megavolts
  • A millivolt is a thousandth of a volt and a kilovolt is a thousand
  • Every step only moves the decimal point, so these conversions carry no error at all
  • Negative values work too, since a voltage can sit below whatever you measure it against
Convert Voltage

Current Converter

Where most electronics actually live

Convert amps, milliamps, microamps and kiloamps instantly, with the exact factor shown. Free online current converter.

  • 4 units: microamps, milliamps, amps and kiloamps
  • A charger rated 2,000 mA is simply 2 A written a different way
  • All four are clean powers of ten, so converting only moves the decimal point
  • Nothing is lost in either direction, however many times you convert
Convert Current

Density Converter

Water is the reference for all of it

Convert density between kg/m3, g/cm3, lb/ft3 and g/ml, with exact factors shown. Free online density converter.

  • 6 units: kg/m³, g/cm³, g/mL, kg/L, and pounds per cubic foot and inch
  • Water sits almost exactly at 1,000 kg/m³, which is 1 g/cm³ and 1 g/mL
  • The same density written three ways, which makes it a quick sanity check on any answer
  • Under 1 g/cm³ floats and over it sinks, so the number tells you something immediately
Convert Density

Fuel Economy Converter

A division, not a multiplication

Convert mpg to L/100km and km/L, with UK and US gallons kept separate. Free fuel economy converter, instant answers.

  • 4 units: L/100km, km per litre, US mpg and UK mpg
  • Higher mpg means a lower L/100km, because the two count opposite things
  • mpg is distance for a fixed amount of fuel; L/100km is fuel for a fixed distance
  • US and UK gallons differ, so their mpg figures are not interchangeable either
Convert Fuel Economy

Cooking Converter

Cups are a volume, and not all the same size

Convert cups to ml, tablespoons, grams and ounces. US, UK and metric cups kept separate, with ingredient weights. Free.

  • 12 units: millilitres and litres with US, imperial and metric spoons and cups
  • A US cup is 236.6 mL and a metric cup is 250 mL, which is a real difference in a recipe
  • An Australian tablespoon is 20 mL where most others are 15
  • It will not turn a cup into grams, because that needs the ingredient, and it says so instead of guessing
Convert Cooking Units
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Which Converter Do I Need?

Find the conversion you are actually after.

What you are trying to convert Use this
Metres to feet, cm to inches, km to miles Length Converter soon
Kilograms to pounds, ounces, stones and tons Weight Converter soon
Celsius to Fahrenheit or Kelvin Temperature Converter soon
Square feet, acres, marla and kanal Area Converter soon
Litres to gallons, cups and pints Volume Converter soon
km/h to mph, knots and Mach Speed Converter soon
MB to GB, and why a 1 TB drive shows 931 GB Data Storage Converter soon
Lakh and crore to million and billion Number System Converter soon
Cups and spoons to millilitres for a recipe Cooking Converter soon
mpg to L/100km Fuel Economy Converter soon
Minutes to hours, days to weeks, a duration in seconds Time Converter soon
Joules to calories, kWh on an electricity bill Energy Converter soon
Watts to horsepower on a motor or an engine Power Converter soon
PSI to bar for a tyre, kPa on a gauge Pressure Converter soon
Newtons to kilogram-force or pounds-force Force Converter soon
Degrees to radians, or a bearing in gradians Angle Converter soon
Hertz to kHz, MHz and GHz Frequency Converter soon
Amps to milliamps on a charger or a supply Current Converter soon
Volts to millivolts or kilovolts Voltage Converter soon
kg/m³ to g/cm³ for a material spec Density Converter soon

How These Converters Work

Four steps, and none of them involve a server.

1
Pick the converter

Length, weight, temperature and data, because each kind of measurement has its own page with its own units.

2
Choose the two units

Set the unit you have and the unit you want. A swap button flips them without retyping.

3
Type the amount

The answer appears as you type, with no convert button, and nothing is sent anywhere.

4
Save what you repeat

Keep pairs you use often, and pick recent conversions back up from history. Both live on this device only.

Why These Instead of a Quick Search

The details a one-line answer usually skips.

Exact by definition

An inch is 0.0254 m and a pound 0.45359237 kg by definition, not by rounding. Where a unit is genuinely approximate, the tool says so.

One honest engine

Every converter runs the same base-unit engine, with real formulas where multiplication is not enough, since temperature shifts and fuel economy divides.

US, imperial, metric apart

Gallons, pints, cups and tons say which family they belong to, so a recipe or a fuel figure converts the way it was meant.

Private and offline

The factors ship with the page. No account, no upload and no server call, and it keeps working when the connection drops.

About WizTools Unit Converters

A unit converter looks too simple to get wrong, which is exactly why so many do. The arithmetic is easy; the definitions are where the trouble lives. Which gallon did you mean? Is that a short ton or a long one? Does your kilobyte hold 1,000 bytes or 1,024? These converters take those questions seriously and answer them on the page rather than quietly picking one for you.

Each converter is its own page, but they share one engine. Every unit is defined by its relationship to a single base unit, whether a metre, a kilogram or a byte, and every conversion goes to that base and out again. Nothing is hard-coded pair by pair, because that is how converters end up right in one direction and wrong in the other. Where a multiplication is not enough, a real formula takes over: temperature shifts as well as scales, and fuel economy divides rather than multiplies.

Everything happens in your browser. There is no account, no upload and no server call: the factors ship with the page, the arithmetic runs on your machine, and your history and saved pairs stay in your own local storage. That makes each tool fast, private and usable offline, and it means the numbers you type are nobody's business but yours.

Frequently Asked Questions

Common questions about converting units here.

Most conversions are exact. Since 1959 an inch is defined as 0.0254 metres and a pound as 0.45359237 kilograms, so those carry no error, and the only rounding is in how many figures you choose to show. A few units are approximate by nature: Mach depends on air temperature, horsepower has competing definitions and calendar months vary. Each of those is labelled where it appears.

Because each measurement brings its own units, its own common questions and its own traps, and a focused page is faster to use and easier to trust than one long list. They all share the same engine underneath, so the arithmetic is identical, and only the units on screen change.

Usually because one of them rounded a factor and the other did not. Some conversions are exact by definition, so an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg, and those never drift however many decimal places you ask for. Others are approximate by nature, such as the calorie, where several slightly different definitions are in use, or Mach, which changes with air temperature. These converters keep the exact factors exact and label the approximate ones as approximate. If a difference shows up at the fourth decimal place, it is almost always a rounded factor rather than a mistake.

The cooking converter, and it is deliberately separate from the volume converter for a reason worth knowing: a cup of flour and a cup of water weigh completely different amounts. Volume to volume is straightforward arithmetic, so litres to pints works for anything. Grams to cups does not, because it depends entirely on what you are measuring, and a converter offering one number for every ingredient is guessing on your behalf. The cooking page handles ingredients individually.

No. An imperial gallon is 4.54609 litres, a US gallon 3.785412 litres, about 20% apart, and pints and fluid ounces differ too. Every unit in the volume and cooking converters says which family it belongs to.

Only in your own browser. Each converter is entirely client-side: nothing you type is uploaded, and history, saved pairs and settings live in this browser's local storage on this device. Clearing them in Settings removes them for good.

Once a page has loaded, yes. All the conversion factors are already in the page, so it keeps working if you lose your connection. There is no lookup, no API call and no waiting.

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