Unit converter online

How to use the unit converter

1. Choose a category: length, weight, volume, area, or temperature.
2. Choose the unit you're converting from and the unit you're converting to.
3. Enter the value.
4. Read the converted result, which updates as you type or change units.

Changing the category refreshes the available From/To unit choices to match that category, since units from different categories (like meters and kilograms) can't be converted into each other.

Supported formats

Value accepts positive or negative decimal numbers (negative values are meaningful for temperature). Length covers millimeters through miles; weight covers milligrams through pounds and tonnes; volume covers milliliters through US gallons; area covers square millimeters through acres and hectares; temperature covers Celsius, Fahrenheit, and Kelvin.

How conversions work across categories

For length, weight, volume, and area, this converter uses a fixed base unit per category (meters for length, kilograms for weight, liters for volume, square meters for area) and converts your input to that base unit first, then from the base unit to your target unit — a standard two-step approach that keeps the underlying conversion factors simple and accurate regardless of which two units you pick. Temperature is handled differently because Celsius, Fahrenheit, and Kelvin don't share a common zero point or scale the way length or weight units do; converting between them requires specific formulas (like °F = °C × 9/5 + 32) rather than a simple multiplication factor.

Best practices

• Double-check the category matches your units before reading the result; switching categories resets the available unit choices.
• Use the most precise unit available for small measurements (millimeters rather than meters for something a few centimeters long) to avoid working with awkward decimal results.
• For temperature, remember 0 is not "nothing" the way it is for length or weight; 0°C is a specific, meaningful temperature (freezing point of water), not an absence of temperature.

Common mistakes to avoid

• Trying to convert between categories, like length to weight; these are fundamentally different physical quantities and this tool correctly keeps them separate.
• Assuming temperature converts with a simple multiplier like other units. A "2x" relationship doesn't exist between Celsius and Fahrenheit the way it does between, say, meters and centimeters; the formulas involve both multiplication and addition.
• Confusing US and UK volume units. This converter uses US customary volume units (US gallons, US cups); UK imperial volume units are numerically different and not included.

Real-world use cases

• Converting a recipe's measurements between metric and US customary units.
• Converting a product's dimensions or weight for international shipping or shopping.
• Converting a weather forecast's temperature between Celsius and Fahrenheit.
• Converting a property or land area between square meters, acres, and hectares.
• Converting a liquid volume for a home brewing, canning, or DIY project between milliliters and US cups or gallons.

Worked example: a few common conversions

Common everyday conversions across different categories:

Metric vs. imperial: why both systems still matter

Most of the world uses the metric system for everyday measurement, while the United States primarily uses a version of the imperial (US customary) system for common tasks like cooking, body weight, and driving distances. This creates genuine friction: a recipe written in cups and Fahrenheit doesn't translate directly for someone used to milliliters and Celsius, and a product's advertised weight in pounds needs converting for someone used to kilograms. Neither system is inherently "correct"; they're just different conventions, and the practical reality is that anyone dealing with international recipes, travel, shopping, or shipping regularly needs to convert between them. This tool exists specifically to remove the friction of doing that conversion by hand or hunting down the right conversion factor each time.

Limitations

This converter covers common everyday units across five categories; it does not include specialized units (like nautical miles, troy ounces, or UK imperial volume units) or currency, which has its own dedicated currency converter since exchange rates change daily and require live data rather than a fixed conversion factor.

Privacy

All conversion happens locally in your browser using fixed conversion factors. Nothing is sent to a server. See the privacy policy for the site's full data handling approach.

Troubleshooting

• If the unit dropdowns look empty or wrong, re-select the category to refresh them.
• If you need a currency conversion, use the dedicated currency converter, which fetches live exchange rates rather than using a fixed factor.
• If a specific unit you need isn't listed, it may not be included in this converter's supported unit list for that category.

Conclusion

Use this converter for quick, accurate unit conversions across length, weight, volume, area, and temperature. For currency conversion specifically, see the currency converter, which uses live exchange rates instead of a fixed factor.