Unit Converter — Length, Weight, Temperature, Free & Private
Convert between units of length, weight, temperature, volume, and speed. All values update in real time. Runs in your browser — no upload, no account, no logs.
How to use this tool
- Select the unit category (length, weight, temperature, etc.).
- Enter a value and select the source unit.
- Read the converted result in the target unit.
About Unit Converter
The unit converter handles five families of measurement: length, weight, temperature, volume, and speed. Length covers metres, kilometres, centimetres, millimetres, miles, yards, feet, and inches; weight spans kilograms, grams, milligrams, pounds, ounces, and metric tons; volume includes litres, millilitres, cubic metres, US gallons, quarts, and cups; and speed covers metres per second, kilometres per hour, miles per hour, and knots. You pick a category, choose a source unit and a target unit, type a number, and the result updates immediately as you type.
Conversions use a two-stage model rather than a giant lookup table of every possible pair. Each value is first converted to a base unit for its category using a fixed factor, then from that base unit into the target unit. For example, one mile is defined as 1609.344 metres and one pound as 0.453592 kilograms, so a mile-to-kilometre conversion routes through metres internally. This keeps the math consistent and avoids the rounding drift you get when chaining many intermediate factors. Temperature is the exception: Celsius, Fahrenheit, and Kelvin are related by formulas rather than simple multipliers, so the converter applies the proper offset-and-scale equations such as multiplying by nine-fifths and adding 32.
Results are shown to roughly eight significant digits, which is more than enough for everyday recipes, travel distances, shipping weights, and engineering estimates. When a value becomes extremely large (around a billion or more) or extremely small (below one ten-thousandth), the output switches to scientific notation so the display stays readable instead of printing a long string of zeros. A copy button lets you grab the converted figure for pasting into a spreadsheet or document, and a clear button resets the input.
The tool covers common, widely used units rather than every obscure historical or regional measure, so you will not find things like nautical leagues, troy ounces, or imperial versus US fluid distinctions beyond what is listed. Because the converter works on numbers, it treats temperature inputs as point values on each scale and converts them directly, which is what you want for reading off a thermostat or a recipe rather than for converting a temperature difference. Everything is computed locally in your browser with plain arithmetic, so there is nothing to upload and no waiting on a server.
Frequently Asked Questions
- Which unit categories and units are supported?
- There are five categories: length, weight, temperature, volume, and speed. Length offers eight units from millimetres up to miles, weight offers six from milligrams to metric tons, volume offers six including US gallons and cups, and speed offers metres per second, kilometres per hour, miles per hour, and knots. Temperature covers Celsius, Fahrenheit, and Kelvin.
- How accurate are the conversions?
- Each result is computed to about eight significant digits using standard conversion factors, such as 1609.344 metres per mile and 0.453592 kilograms per pound. That precision comfortably exceeds what most practical tasks need. For very large or very small numbers the display uses scientific notation so the figure stays legible.
- Why does it convert through a base unit?
- Instead of storing a factor for every pair of units, the converter turns your value into a single base unit for the category and then into the target unit. This two-step approach keeps every conversion in a category mathematically consistent and prevents the small rounding errors that accumulate when you multiply through several intermediate conversions.
- How is temperature handled differently from other units?
- Length, weight, volume, and speed are related by simple multiplication factors, but temperature scales differ by both an offset and a slope. The converter applies the correct equations directly, for instance multiplying Celsius by nine-fifths and adding 32 to get Fahrenheit, or adding 273.15 to reach Kelvin, so a temperature reading is converted as a true point value on each scale.
- Can I convert units that are not listed?
- No. The tool focuses on the most commonly used units in each category and does not include every historical, scientific, or regional measure. If a unit such as a nautical league or a troy ounce is not in the dropdown, it is not supported. The listed units cover the large majority of everyday and professional needs.
- Does the result update automatically?
- Yes. As soon as you change the input number, the source unit, or the target unit, the result recalculates in real time. There is no convert button to press. A copy button lets you grab the answer and a clear button empties the input field.
- Is my input sent to a server?
- No. Every calculation is plain JavaScript arithmetic that runs in your browser, so the numbers you enter never leave your device and there is no network request involved in producing a result.
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<iframe src="https://brevio.pro/embed/unit-converter" width="100%" height="600" loading="lazy" style="border:1px solid #e5e5e5;border-radius:8px" title="Unit Converter — brevio"></iframe> <p style="font:12px/1.4 sans-serif"><a href="https://brevio.pro/tools/unit-converter">Unit Converter</a> by <a href="https://brevio.pro">brevio</a></p>