How many feet and inches are in a metre?

1 metre is 3.28084 feet or 39.3701 inches, using the exact definitions of 1 ft = 0.3048 m and 1 in = 0.0254 m. Type 1 with the unit m in the Length category and the table shows feet, inches, yards, miles and every other length unit at once.

What is the formula for Celsius to Fahrenheit?

°F = °C × 9/5 + 32, and the reverse is °C = (°F − 32) × 5/9. Because there is an offset as well as a scale factor, temperature cannot be converted with a single multiplier; this tool applies the full formula and also handles Kelvin (°C + 273.15) and Rankine. Handy checks: 0 °C = 32 °F, 100 °C = 212 °F, 37 °C = 98.6 °F.

Are US and UK gallons different?

Yes. A US gallon is 3.785411784 litres and a UK (imperial) gallon is 4.54609 litres, about 20 percent more. US recipes and fuel prices use the US gallon; the UK, Ireland and some Commonwealth countries use the imperial one. Both are listed separately in the Volume category, along with US fluid ounces, cups, pints and quarts.

How fast is a knot in km/h and mph?

1 knot is exactly 1.852 km/h, which is 0.5144 m/s or 1.1508 mph. A knot is one nautical mile per hour, and the nautical mile is defined as 1852 m, which is why aviation and marine speeds use it. Enter 1 with the unit kt in the Speed category to see all equivalents.

Why is a month 30 days and a year 365 days?

Calendar months vary between 28 and 31 days and leap years add a day, so no single factor is exact. The Time category uses the common approximations of 30 days per month and 365 days per year, and says so in the unit names. For precise date arithmetic, such as the number of days between two dates, use a calendar or date library rather than a unit ratio.

Which Japanese units are included?

The Length category has the shaku (10/33 m, about 30.3 cm), Mass has the kan (3.75 kg) and momme (3.75 g), and Area has the tsubo (400/121 m², about 3.306 m²) and the jo, a tatami mat taken as 1.8225 m². They appear alongside metric and imperial units, which is useful when reading Japanese property listings, textile weights or historical measurements.

Can I control the number of decimal places?

Not manually. Every result is rounded to ten significant digits and the display precision adapts to the size of the number: large values get fewer decimals, values below 1 get up to eight, integers are shown without decimals, and anything below 0.0001 or at 1e15 and above is shown in exponential form. Copy the value and round it further in your spreadsheet if you need a fixed format.

Does it convert data sizes like MB and GB, or currencies?

No. This tool covers physical measurements only. Data units involve the 1000-versus-1024 question and currencies need live rates, so both are out of scope here. Bits, bytes and network math are also outside this tool; for IP address ranges, the Subnet Calculator handles CIDR and mask arithmetic.

How do I convert in the opposite direction?

Click the row of the unit you want to start from. That unit becomes the input, the displayed value is copied into the field, and the whole table is recalculated from it. Going from "10 cm in inches" to "3 inches in cm" therefore takes one click and a new number.

Are the values I convert sent to a server?

No. Conversions are computed by JavaScript in your browser and no value is transmitted or logged. The only stored item is the last category you used, kept in your browser's local storage so the same tab opens next time.

Unit Converter

Convert length, weight, temperature, area, volume, speed, time, angle, pressure and energy across 80+ units at once. Runs entirely in your browser.

Instead of picking a source and a target unit one pair at a time, type a single value and read the answer in every unit of that category at once: 5 miles as kilometres, metres, yards and nautical miles side by side. It covers the conversions that come up in recipes, travel, DIY, engineering notes and homework, and one click on any result row makes that unit the new starting point.

Unit Converter

// Enter a value and unit

// Results

💡 Click a result row to make that unit the source. Everything is computed in your browser; your input is never sent to a server.

// Unit Converter: Features

Ten categories, more than 80 units

Length (mm, cm, m, km, inch, foot, yard, mile, nautical mile, Japanese shaku), mass (mg, g, kg, tonne, ounce, pound, plus Japanese kan and momme), temperature (Celsius, Fahrenheit, Kelvin, Rankine), area (mm² to km², are, hectare, square foot, square yard, acre, tsubo, jo), volume (mL, cL, dL, L, m³, cm³, US fluid ounce, cup, pint, quart and gallon, UK gallon, 200 mL Japanese cup), speed (m/s, km/h, mph, ft/s, knot, Mach), time (ms to years), angle (degree, radian, gradian, turn, arcminute, arcsecond), pressure (Pa, hPa, kPa, MPa, bar, atm, mmHg, psi) and energy (J, kJ, cal, kcal, Wh, kWh, eV, BTU).

Every conversion in one table

Enter a number and choose its unit, and the full list of units in that category is recalculated live. There is no need to guess which pair you will need next: 1 pound shows grams, kilograms, ounces and the rest in one view. Clicking any row makes that unit the input, with the converted value carried over, so you can hop from "100 km in miles" to "40 miles in km" without retyping. The last category you used is remembered for your next visit.

Exact definitions, correct temperature math

Conversions use the international definitions: 1 inch is exactly 2.54 cm, 1 pound is 0.45359237 kg, 1 US gallon is 3.785411784 L and 1 UK gallon is 4.54609 L, 1 knot is 1852 m per hour, and Mach 1 is taken as 340.3 m/s at sea level and 15 °C. Temperature is handled as a linear conversion with an offset rather than a simple ratio, so 0 °C gives 32 °F, 100 °C gives 212 °F and -40 is the same in both scales. Time uses 30 days for a month and 365 days for a year, which is stated in the unit names.

Readable numbers at any scale

Results are rounded to ten significant digits, formatted with thousands separators, and switched to exponential notation such as 1.602177e-19 only when the value is below 0.0001 or at 1e15 and above. Whole numbers are shown without a decimal tail. That keeps everyday values like 3.28084 feet readable while still handling electron-volt or square-millimetre extremes without a wall of zeros.

Your last category is remembered, nothing else is kept

All arithmetic runs in your browser; the value you type and the results are never sent to a server. The only thing saved is the category you last opened, kept in local storage so the tool reopens where you left it. Time units convert durations only; to move a clock time between regions, use the Time Zone Converter, which applies daylight saving rules.

// Unit Converter: FAQ

How many feet and inches are in a metre?: 1 metre is 3.28084 feet or 39.3701 inches, using the exact definitions of 1 ft = 0.3048 m and 1 in = 0.0254 m. Type 1 with the unit m in the Length category and the table shows feet, inches, yards, miles and every other length unit at once.
What is the formula for Celsius to Fahrenheit?: °F = °C × 9/5 + 32, and the reverse is °C = (°F − 32) × 5/9. Because there is an offset as well as a scale factor, temperature cannot be converted with a single multiplier; this tool applies the full formula and also handles Kelvin (°C + 273.15) and Rankine. Handy checks: 0 °C = 32 °F, 100 °C = 212 °F, 37 °C = 98.6 °F.
Are US and UK gallons different?: Yes. A US gallon is 3.785411784 litres and a UK (imperial) gallon is 4.54609 litres, about 20 percent more. US recipes and fuel prices use the US gallon; the UK, Ireland and some Commonwealth countries use the imperial one. Both are listed separately in the Volume category, along with US fluid ounces, cups, pints and quarts.
How fast is a knot in km/h and mph?: 1 knot is exactly 1.852 km/h, which is 0.5144 m/s or 1.1508 mph. A knot is one nautical mile per hour, and the nautical mile is defined as 1852 m, which is why aviation and marine speeds use it. Enter 1 with the unit kt in the Speed category to see all equivalents.
Why is a month 30 days and a year 365 days?: Calendar months vary between 28 and 31 days and leap years add a day, so no single factor is exact. The Time category uses the common approximations of 30 days per month and 365 days per year, and says so in the unit names. For precise date arithmetic, such as the number of days between two dates, use a calendar or date library rather than a unit ratio.
Which Japanese units are included?: The Length category has the shaku (10/33 m, about 30.3 cm), Mass has the kan (3.75 kg) and momme (3.75 g), and Area has the tsubo (400/121 m², about 3.306 m²) and the jo, a tatami mat taken as 1.8225 m². They appear alongside metric and imperial units, which is useful when reading Japanese property listings, textile weights or historical measurements.
Can I control the number of decimal places?: Not manually. Every result is rounded to ten significant digits and the display precision adapts to the size of the number: large values get fewer decimals, values below 1 get up to eight, integers are shown without decimals, and anything below 0.0001 or at 1e15 and above is shown in exponential form. Copy the value and round it further in your spreadsheet if you need a fixed format.
Does it convert data sizes like MB and GB, or currencies?: No. This tool covers physical measurements only. Data units involve the 1000-versus-1024 question and currencies need live rates, so both are out of scope here. Bits, bytes and network math are also outside this tool; for IP address ranges, the Subnet Calculator handles CIDR and mask arithmetic.
How do I convert in the opposite direction?: Click the row of the unit you want to start from. That unit becomes the input, the displayed value is copied into the field, and the whole table is recalculated from it. Going from "10 cm in inches" to "3 inches in cm" therefore takes one click and a new number.
Are the values I convert sent to a server?: No. Conversions are computed by JavaScript in your browser and no value is transmitted or logged. The only stored item is the last category you used, kept in your browser's local storage so the same tab opens next time.

// How to Use Unit Converter

Choose a category

Pick Length, Mass, Temperature, Area, Volume, Speed, Time, Angle, Pressure or Energy from the buttons at the top. The tool remembers your last category and reopens it on your next visit.
Enter a value and its unit

Type a number and select the unit it is in. The list below updates instantly with the value expressed in every unit of the category, so metres to feet, kilograms to pounds or Celsius to Fahrenheit are all visible at once.
Click a row to switch the base unit

Select any result row to make that unit the new input, keeping its value. This lets you chain conversions in both directions, for example checking 100 km in miles and then 40 miles back in kilometres, without retyping.

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