Starlight Tools

Unit Converter

Convert length, weight, temperature, area, volume, speed, pressure, energy, power, force, angle, fuel economy, frequency, data transfer, density, torque, acceleration, time, and digital storage. Private by design - everything runs locally in your browser.

Choose Units & Convert

Type a unit or pair and press Enter, or choose a common shortcut below.
Smart input supports commas, negatives, scientific notation, fractions, compound feet/inches, slashes like m/s, and common unit names.
Result
From To

Shortcuts: Enter convert · S swap units · Ctrl/Cmd + K focus search.

About this unit converter

This tool covers everyday, school, cooking, travel, digital, and engineering conversions in one place. Use the search field for a direct pair such as meters to feet, paste a value such as 10 km, or browse the categories manually.

Supported categories

  • Core measurements: length, mass, temperature, area, volume, speed, and time.
  • Science and engineering: pressure, energy, power, force, angle, frequency, density, torque, and acceleration.
  • Digital and transport: decimal and binary storage, data transfer rates, and fuel economy.
  • Special notes: temperature and fuel economy use formulas; area and volume use squared or cubed relationships; months and years are average time approximations.

Parsing and formatting

  • Smart input: Recognizes common names and symbols, including gallons, fahrenheit, micrograms, m/s, MB/s, and 5 ft 8 in.
  • Precision: Choose decimal places or significant figures, force scientific notation, or add fraction-style inch and feet-plus-inches output.
  • Result detail: Each conversion shows the formula, inverse result, one-unit rate, and a small table for common amounts.

Common conversion shortcuts

Practical conversion examples

Length conversion examples

  • 180 cm = 70.866142 inches, or about 5 ft 10.9 in.
  • 10 km = 6.213712 miles for road-race distances.
  • 12 ft = 3.6576 m for room and material measurements.

Weight and mass conversion examples

  • 70 kg = 154.323584 lb.
  • 10 st = 140 lb = 63.502932 kg.
  • 500 micrograms = 0.5 mg for small mass readings.

Volume conversion examples

  • 2 liters = 0.528344 US gallons.
  • 1 US tablespoon = 3 US teaspoons.
  • 1 imperial gallon = 4.54609 L, larger than a US gallon.

Digital storage conversion examples

  • 1 MB = 1,000,000 bytes.
  • 1 MiB = 1,048,576 bytes.
  • 100 Mbps = 12.5 MB/s before network overhead.

Accuracy and methodology

The converter uses exact definitions where standards define them, such as 1 inch = 2.54 cm exactly and 1 pound = 0.45359237 kg exactly. Approximated practical units, such as calendar months and years in the time category, are labeled in the category notes. Internal calculations keep full JavaScript number precision; rounding is applied only when the result is displayed.

  • Metric and customary factors are checked against NIST Special Publication 811 and NIST SI guidance.
  • Digital decimal and binary prefixes follow NIST guidance on IEC binary prefixes, where MB and MiB intentionally mean different byte counts.
  • Formula categories, including temperature and fuel economy, are calculated with category-specific formulas rather than simple multipliers.

How to convert units online

  1. Search for a pair such as meters to feet, or choose a category and units manually.
  2. Enter a value, including smart input such as 10 km, 1/2 gallon, 5 ft 8 in, or 3.2e6 bytes.
  3. Set decimal places or significant figures, then use scientific notation or fraction-style output when helpful.
  4. Read the result, formula, inverse conversion, one-unit rate, and common amounts table.

Unit converter FAQ

What is the difference between weight and mass?

Mass is the amount of matter in an object. Weight is the force caused by gravity acting on that mass. Everyday pound and kilogram conversions usually compare mass-like quantities.

Are US and imperial gallons different?

Yes. A US gallon is 3.785411784 liters, while an imperial gallon is 4.54609 liters.

Why are MB and MiB different?

MB uses decimal SI prefixes, so 1 MB is 1,000,000 bytes. MiB uses binary IEC prefixes, so 1 MiB is 1,048,576 bytes.

How accurate are the results?

Exact definitions are used where available, approximations are labeled, and display rounding is controlled by the precision settings.

Can I convert feet and inches together?

Yes. Enter values such as 5 ft 8 in or turn on fraction-style output for practical inch and feet-and-inches readings.

Which temperature formulas are used?

The converter uses F = C x 9/5 + 32, C = (F - 32) x 5/9, K = C + 273.15, and R = (C + 273.15) x 9/5.

Why do area and volume conversions square or cube the factor?

Area has two length dimensions, so the length factor is squared. Volume has three length dimensions, so the factor is cubed.

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