Unit Converter Hub

Instant conversions for length, weight, temperature, volume, area, speed, time, data, energy & pressure

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Unit Value

How Unit Conversion Works

Every unit conversion reduces to one of two operations: multiplication by a factor (for units within the same physical quantity that share an absolute zero) or a formula that accounts for offset scales (like temperature).

Factor-based conversion (most units)

For length, weight, volume, speed, etc., every unit is defined relative to a base SI unit. For example, the meter is the SI base for length. To convert 5 miles to kilometers:

  1. 5 miles × 1609.344 m/mile = 8046.72 m
  2. 8046.72 m ÷ 1000 m/km = 8.04672 km

This converter stores the SI factor for each unit and performs the two-step conversion in one multiplication: value × (from_factor / to_factor).

Formula-based conversion (temperature)

Temperature scales have different zero points (°C zero ≠ °F zero), so a simple factor doesn't work. The formulas are:

  • °C → °F: multiply by 9/5, add 32
  • °F → °C: subtract 32, multiply by 5/9
  • °C → K: add 273.15
  • K → °C: subtract 273.15

Did You Know?

Length
A mile is exactly 1,609.344 meters — defined internationally in 1959.
Weight
The kilogram was redefined in 2019 based on Planck's constant, not a physical artifact.
Temperature
Absolute zero (0 K) is −273.15 °C — the coldest possible temperature in the universe.
Volume
The liter was originally defined as the volume of 1 kg of water at 4 °C.
Speed
The speed of light is exactly 299,792,458 m/s — used to define the meter itself.
Data
A gigabyte (SI) = 1 billion bytes; a gibibyte (binary) = 1,073,741,824 bytes.

Frequently Asked Questions

How many centimeters are in an inch?
Exactly 2.54 centimeters per inch, by international definition since 1959.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (1.8) and add 32. Example: 100 °C × 1.8 + 32 = 212 °F. Body temperature 37 °C = 98.6 °F.
How many pounds are in a kilogram?
One kilogram equals exactly 2.2046226218 pounds. For everyday use, 1 kg ≈ 2.205 lbs.
How many bytes are in a gigabyte?
In SI (decimal) terms: 1 GB = 1,000,000,000 bytes. In binary terms: 1 GiB = 1,073,741,824 bytes. Hard drives use decimal; OS often shows binary, causing the apparent size discrepancy.
Why does the converter show a formula instead of just the result?
Showing the formula helps you verify results and remember the conversion for next time — useful for students and professionals who need to explain their calculations.
Can I share a specific conversion?
Yes — click the Share button to copy a URL encoding the current category, units, and value. Anyone opening that URL will see the same conversion pre-filled.