Unit Conversion Basics: Metric ↔ Imperial

Five you should memorize

• 1 meter = 3.281 feet
• 1 kilogram = 2.205 pounds
• 1 liter = 0.264 US gallons
• 1 kilometer = 0.621 miles
• 0 °C = 32 °F; each additional 1 °C = 1.8 °F

Why dimensional analysis matters

Multiplying by 1 — in the form of a ratio like (1 m / 3.281 ft) — is the trick. Line up units so the ones you don't want cancel. This is how spacecraft avoid confusing Newtons with pound-force.

When to trust a calculator

Any time you can. Human arithmetic breaks on cube conversions (m³ ↔ ft³ needs 3.281³, not 3.281). A converter never forgets to cube the factor.