Unit Converter

Convert lengths, weights, areas, temperatures, volumes, and time units.

How to Use Unit Converter

  1. Choose Length, Weight, Area or Temperature at the top.
  2. Type your number in the From box and pick its unit.
  3. Pick the unit you want in the To box. The result updates as you type.
  4. Use the arrow button between the two boxes to swap the units.

What it converts

Length covers meters, kilometers, centimeters, millimeters, miles, yards, feet and inches. Weight covers kilograms, grams, milligrams, pounds and ounces. Area covers square meters, square kilometers, square feet, acres and hectares. Temperature covers Celsius, Fahrenheit and Kelvin.

That's a deliberately short list of the units people look up most. There are no volume or cooking measures yet, so for cups, gallons or liters you'll need another converter for now.

How exact are the answers?

The length and weight factors are the official definitions, not rounded approximations. An inch is exactly 2.54 cm, a foot is exactly 0.3048 m, a mile is exactly 1,609.344 m and a pound is exactly 0.45359237 kg. So a result like 1 mile = 1.609344 km comes out exact.

Results are shown to six decimal places (four for temperature), which is more than enough for homework, recipes, DIY and most technical checks.

Temperature works differently

Length, weight and area are simple multiplications, but temperature scales start from different zero points, so the tool converts through Celsius. The formulas are °F = °C × 9/5 + 32 and K = °C + 273.15. Two handy sanity checks: 0 °C is 32 °F, and -40 is the same in Celsius and Fahrenheit.

Kelvin can't go below zero. If you get a negative Kelvin result, the temperature you started with is below absolute zero, which isn't physically possible.

Key Features & Practical Use Cases

  • Turning a height in feet and inches into centimeters for a form, or the other way round.
  • Checking a body weight or parcel weight in kilograms against pounds.
  • Comparing land listed in acres with plots listed in hectares or square meters.
  • Reading an oven or weather temperature given in Fahrenheit when you think in Celsius.
  • Double-checking unit conversions in physics or chemistry homework.

Frequently Asked Questions

How many centimeters are in an inch?

Exactly 2.54. The inch has been defined that way since 1959, so 12 inches (one foot) is exactly 30.48 cm.

How do I convert kg to pounds in my head?

Multiply by 2.2 for a quick estimate. The exact factor is about 2.20462, so 70 kg is roughly 154.3 lb. Use the converter when the decimals matter.

How big is an acre compared to a hectare?

One hectare is about 2.471 acres, and one acre is about 4,047 square meters, or roughly 40% of a hectare.

Can I convert volume, speed or currency?

Not with this tool. It covers length, weight, area and temperature. Currency rates change daily and would need live data from a server, which this site doesn't use.

Can I type into the result box?

No, the To box is read-only. Type into From, and use the swap button if you want to convert in the other direction.

About OneClickly

OneClickly is a set of 119 free tools for PDFs, images, text, everyday math and code. They run in your browser, so the files and text you work with stay on your device.

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