Universal Unit Converter
Convert between Length, Mass, Volume, Temperature, Speed, and Time. Real-time, accurate, 100% client-side.
📐 Converted Result:
The conversion factors (six categories)
Each category is a straight multiply-by-a-factor conversion that passes through one base unit per family: metre for length, kilogram for mass, litre for volume, metre/second for speed, second for time. Temperature is the exception - it uses the offset formulas (°F = °C×9/5 + 32, K = °C + 273.15), not a single factor, because its scales do not start at zero.
The defining factors are exact international definitions:
- Length: inch = 0.0254 m (exact) → foot 0.3048, yard 0.9144, mile 1,609.344, nautical mile 1,852 m
- Mass: pound = 0.45359237 kg (exact), ounce = pound/16, stone = 14 lb = 6.35029318 kg
- Volume: US gallon = 231 in³ = 3.785411784 L (exact); UK/imperial gallon = 4.54609 L; cubic inch = 0.016387064 L
- Speed: mph = 0.44704 m/s (exact from mile & hour), knot = 1,852 m / hour
Two things to know (honest limits)
1 · “Year” = 365 days. Time conversion treats a year as exactly 31,536,000 s (365 days), so it ignores leap years; converting years to days over many years drifts by a day per ~4 years. 2 · US vs UK gallons differ. The tool offers both gallon_us and gallon_uk because they are genuinely different volumes - pick the one that matches your region; the same goes for pints and quarts (US values shown).
Sources & review
Imperial/US customary values follow the definitions fixed against SI units (the 1959 international yard and pound agreement and NIST/SI references); SI prefixes and the litre (0.001 m³) are exact by definition. Methodology last reviewed: October 2026. All conversion happens in your browser; nothing is uploaded.
How to Use Unit Converter
Follow these simple steps to get the best results.
Choose a category
Pick one of six categories: length, mass, volume, temperature, speed or time.
Enter a value and pick units
Type the number and choose the source and target units; the conversion updates live as you type, or press Convert to run it.
Copy, swap or clear
Use Swap to flip the unit direction, Copy Result to save the value, or Clear to reset. Every factor is exact and nothing is uploaded.
Frequently Asked Questions
Everything you need to know about Unit Converter.
About the Unit Converter Tool
The Universal Unit Converter by ToolFlic is your all-in-one bridge between different measurement systems. Whether you are dealing with length, mass, volume, temperature, speed or time, our tool provides instant and accurate conversions between metric and imperial units, ensuring you always have the right measurements for your project.
Core Advantages
Simplify complex project requirements and international standards. Our converter is an essential utility for engineers, students, and DIY enthusiasts who need to switch between systems on-the-fly. It's fast, free, and designed to handle professional-grade precision.
Architecture & Security
We implement high-precision conversion constants for every major measurement type. By using a centralized conversion matrix, we ensure that every result is mathematically accurate and consistent, all while processing data locally on your computer.
Under the Hood: the Unit Converter explained properly
No marketing filler - just the mechanics, the trade-offs and the real limits, explained clearly.
How it actually works
Six categories are covered - length, mass, volume, temperature, speed and time - with 44 units between them. Every unit in a ratio category is defined by its size in that category's base unit, and a conversion is a multiplication to the base and a division out of it, so adding a unit means adding one number rather than writing a pair of rules.
Temperature is the exception and is handled as formulas rather than ratios, because a scale with a shifted zero cannot be scaled: Celsius, Fahrenheit and Kelvin are converted through the freezing and boiling points, which is why minus signs work correctly here and would not under a factor method. The factor actually used is shown under the result in scientific notation, so you can see the precision you are working with.
What that means for your results
Definitions are the exact international ones: an inch is 0.0254 metres by agreement, a pound is 0.45359237 kilograms, a nautical mile is 1852 metres, and the US and UK gallons are kept separate because they are genuinely different volumes. Nothing is rounded to a convenient number.
Results are printed to ten decimal places with trailing zeros removed, which is wide enough for engineering work and short enough to read, and unit labels appear beside both fields so a swap cannot be mistaken.
Where it falls short - honestly
Only these six families are supported. There is no area, pressure, energy, data-size, currency or cooking measure, and no way to combine units; a two-unit calculation such as density belongs in a spreadsheet.
Computation goes through JavaScript's double precision, so a conversion needing more than about sixteen significant digits carries the usual rounding, and very large or very small values are shown in exponential form. Currency is deliberately absent: rates change every minute, so an offline figure would be wrong rather than merely old - use Currency Converter.
A real end-to-end workflow
Pick a category, choose the two units, type the value and read the result; the swap button reverses the pair for the return conversion, which is the fastest way to sanity-check a figure in both directions.
For date and time spans rather than physical units, Date Calculator and Epoch Timestamp Converter are the right tools; for a length plus a width, use Length Converter on each dimension and multiply afterwards, since area is not a length.
In-Depth Guides Using This Tool
Tested workflows, exact sizes and limits - written step by step by the ToolFlic team.
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