Unit Converter
Free Online Unit Converter – Length, Weight, Temperature & More
Choose a measurement category, enter a source value, and select the two units to translate a quantity within the same category. The converter covers length, mass, time, temperature, area, volume, speed, energy, power, pressure, and angle. It is useful for checking a recipe, comparing a travel distance, reading a product specification, or translating a value in technical notes.
Most categories convert through a base unit using fixed factors. Temperature is different because Celsius, Fahrenheit, Kelvin, and Rankine use both a scale and an offset. The formula line shows the relationship used by the current conversion, and the quick-reference panel gives common examples for the selected category.
Length / Distance
Convert between meters, kilometers, miles, feet, inches, centimeters, yards, and nautical miles.
Mass / Weight
Convert between kilograms, grams, pounds, ounces, stones, metric tons, and more.
Temperature
Convert between Celsius, Fahrenheit, Kelvin, and Rankine for weather, cooking, and science.
Time
Convert between seconds, minutes, hours, days, weeks, months, and time units down to nanoseconds.
Volume
Convert between liters, gallons, cups, fluid ounces, milliliters, and more for cooking and science.
Speed / Velocity
Convert between km/h, mph, m/s, knots, and Mach for travel and physics calculations.
How to Use the Unit Converter
- Select a category from the dropdown (e.g., Length / Distance)
- Choose the unit to convert from and the unit to convert to
- Enter your value — results appear instantly
- Click the swap button to quickly reverse the conversion direction
- Click Copy Result to copy the conversion to your clipboard
- Use the Quick Reference panel to see common conversion benchmarks
Good to Know for Accurate Conversions
- Most categories use fixed factors relative to a base unit, so the same input always gives the same result.
- Temperature is different. Celsius, Fahrenheit, Kelvin, and Rankine use both a scale and an offset, not a single factor.
- Watch region-specific units. US and UK gallons differ by about 20%, and "ton" has metric, US, and UK versions.
- Round at the end. Keep full precision through multi-step work, then round once for your final figure.
- New to this? Read Metric and Imperial Unit Conversion Explained.
Frequently Asked Questions
Yes. You can use this tool unlimited times at no cost.
The converter supports Length/Distance, Mass/Weight, Time, Temperature, Area, Volume, Speed/Velocity, Energy/Work, Power, Pressure, and Angle.
The Time category uses an average month length. Calendar months contain different numbers of days, so use the Time & Date Calculator when the exact calendar date matters.
No. All conversions happen locally in your browser.
About VioApps
This unit converter is part of VioApps, a browser-based collection of everyday utility tools. It supports length, mass, temperature, area, volume, speed, power, and more, using deterministic conversion factors so results stay accurate and repeatable across sessions.
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