Precision Unit Conversion for Every Use Case
Whether you're a student, engineer, chef, developer, or traveler, precise unit conversions are critical. Rocking Tools' Unit Converter runs entirely in your browser with no tracking, no sign-up, and no wait times.
Supported Categories
- Length: Metric (km, m, cm, mm, μm), Imperial (mi, yd, ft, in), nautical mile, light year
- Weight / Mass: Metric ton, kilogram, gram, milligram, pound, ounce, stone
- Temperature: Celsius, Fahrenheit, Kelvin, Rankine — via direct formulas
- Area: Square units from mm² to mi², hectares, acres
- Volume: Metric (m³, L, mL) + US culinary (gallon, quart, pint, cup, fl oz, tbsp, tsp)
- Speed: m/s, km/h, mph, knots, ft/s, Mach
- Time: Nanoseconds to years — 10 units
- Data Storage: Bit, byte, KB, MB, GB, TB, PB (binary 1024-based)
- Energy: Joule, kJ, calorie, kcal, Wh, kWh, BTU, foot-pound, electron volt
- Pressure: Pascal, kPa, bar, PSI, atmosphere, Torr, inHg
Unit Conversion Categories
High-Demand Conversion Calculators
How the Conversion Works
All factor-based categories (every category except Temperature) use a base unit approach: the input value is multiplied by the "from unit" factor to reach the base unit, then divided by the "to unit" factor. This single formula handles all combinations correctly.
Temperature uses dedicated formulas with Celsius as the intermediate step, ensuring accuracy across all four temperature scales.
Frequently Asked Questions
How many unit categories are supported?
10 categories covering over 80 individual units: Length, Weight/Mass, Temperature, Area, Volume, Speed, Time, Data Storage, Energy, and Pressure.
How accurate are the conversions?
All conversions use IEEE 754 double-precision floating point arithmetic with up to 15 significant digits internally. Results are displayed with up to 10 significant figures for readability.
Does the tool work offline?
Yes. All conversion math runs locally in your browser using JavaScript. Once the page is loaded, no internet connection is needed.
How does temperature conversion work differently?
Temperature uses direct formulas (not multiplication factors). All values are converted through Celsius as an intermediate step — for example, to convert Fahrenheit to Kelvin, the tool converts F → C → K.
Can I enter values in both the From and To fields?
Yes. Either field is fully editable. Changing the "From" field updates "To", and changing the "To" field back-calculates the "From" value. The ⇄ Swap button also reverses both unit selectors instantly.