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Unit Converter — Length, Weight, Volume, Temperature, Area & Speed

Convert between metric, imperial, and US units instantly. All calculations run in your browser — no data is sent to any server. Free, no sign-up, works offline.

About this tool

This unit converter handles six categories: length, weight, volume, temperature, area, and speed. It covers both metric and imperial/US units, including less common ones like nautical miles, stones, and knots. Temperature conversions use the correct formulas (not just multiplication) to account for different zero points. All calculations happen instantly in your browser — nothing is sent to a server.

How to use

  1. Select a category (Length, Weight, Volume, Temperature, Area, or Speed).
  2. Enter a value and choose the source unit from the dropdown.
  3. Choose the target unit — the result updates automatically.
  4. Click ⇄ to swap the source and target units.

When to use this tool

  • Converting kilometers to miles for travel distances or map readings.
  • Converting kilograms to pounds or ounces for recipes or shipping labels.
  • Converting Celsius to Fahrenheit when reading a foreign weather forecast.
  • Converting hectares to acres for real estate or land measurements.
  • Converting liters to US or UK gallons for fuel or cooking.

Frequently asked questions

How accurate are the conversions?

Conversions use standard internationally accepted factors and are accurate to 10 significant figures.

Does this work offline?

Yes. All calculations run in your browser. Once the page has loaded, you can use it with no internet connection.

What unit categories are supported?

Length, Weight, Volume, Temperature, Area, and Speed, covering metric, imperial, and US units.

Why is temperature handled differently?

Temperature scales have different zero points, so conversion requires a formula, not just multiplication. The tool handles this automatically.

Can I swap units quickly?

Yes. Click the ⇄ button to instantly reverse the source and target units.

Does this include US and UK gallons?

Yes. US gallons (3.785 L) and UK/Imperial gallons (4.546 L) are listed separately because they are different sizes.

Is any data sent to a server?

No. All calculations happen locally in your browser. No values are transmitted or stored.

Is this tool free?

Yes, completely free with no sign-up required and no usage limits.

Everything is calculated locally in your browser — no data is ever sent to a server.