Free Unit Converter — Convert Length, Weight, Temperature, and More

Whether you’re following a recipe in a different measurement system, reading a technical specification, or working across metric and imperial units, SimpleTools Unit Converter handles hundreds of unit conversions instantly — no internet required after the page loads.

Supported Unit Categories

Length

• Metric: nanometre, micrometre, millimetre, centimetre, metre, kilometre
• Imperial: inch, foot, yard, mile
• Nautical: nautical mile
• Astronomical: light year, astronomical unit, parsec

Weight / Mass

• Metric: microgram, milligram, gram, kilogram, metric tonne
• Imperial: ounce, pound, stone, short ton, long ton
• Scientific: atomic mass unit, dalton

Temperature

• Celsius, Fahrenheit, Kelvin, Rankine

Area

• Square centimetre, square metre, square kilometre, hectare
• Square inch, square foot, square yard, square mile, acre

Volume

• Millilitre, litre, cubic metre
• US: teaspoon, tablespoon, fluid ounce, cup, pint, quart, gallon
• UK: teaspoon, tablespoon, fluid ounce, pint, quart, gallon

Speed

• Metres per second, kilometres per hour, miles per hour, knots, Mach number

Digital Storage

• Bit, byte, kilobyte, megabyte, gigabyte, terabyte, petabyte (binary and decimal)

Time

• Millisecond, second, minute, hour, day, week, month, year, decade, century

Pressure

• Pascal, kilopascal, bar, PSI, atmosphere, mmHg

Energy

• Joule, kilojoule, calorie, kilocalorie, watt-hour, kilowatt-hour, BTU, electronvolt

Why Use a Browser-Based Unit Converter?

The privacy argument doesn’t apply as strongly to unit conversion (you’re not sharing sensitive data), but there are practical advantages:

✅ Works offline — no internet needed after first load
✅ No ads or tracking
✅ Instant results — no network round-trip delay
✅ All units available — no “premium” feature gates
✅ Free forever

How It Works

Unit conversion is pure mathematics. The tool maintains a library of conversion factors relative to a base unit in each category:

const lengthFactors = {
  metre: 1,           // base unit
  centimetre: 0.01,
  kilometre: 1000,
  inch: 0.0254,
  foot: 0.3048,
  mile: 1609.344,
};

function convert(value, fromUnit, toUnit) {
  const metres = value * lengthFactors[fromUnit];
  return metres / lengthFactors[toUnit];
}

Temperature is a special case (non-linear conversion) with direct formulas:

• °C to °F: (C × 9/5) + 32
• °F to °C: (F − 32) × 5/9
• °C to K: C + 273.15

All conversions run in the browser — no API calls.

How to Use the Unit Converter

1. Visit simpletools.one/unit-converter
2. Select a category (Length, Weight, Temperature, etc.)
3. Enter the value you want to convert
4. Select the from unit
5. Select the to unit
6. The result updates instantly
7. Swap units with the exchange button to reverse the conversion

Common Conversions at a Glance

Use Cases

• Cooking: US recipes use cups and Fahrenheit; European recipes use grams and Celsius
• Travel: Convert km to miles for distances, kg to lb for luggage limits
• Science: Convert between SI units and practical engineering units
• Construction: Convert between imperial and metric specifications
• Sports: Convert athletic measurements (100 metres vs. 100 yards, etc.)
• Programming: Convert between binary and decimal storage units (MiB vs. MB)

Convert units at simpletools.one/unit-converter — instant, offline-capable, and completely free.