July 12, 2026 · 3 min
Metric vs Imperial: Quick Conversions You Can Do in Your Head
Approximate conversions between metric and imperial units that are close enough for daily life — plus a link to precise calculators.
If you travel or work across measurement systems, memorizing a few approximate conversions saves time.
Length
- 1 meter ≈ 3.3 feet
- 1 kilometer ≈ 0.6 miles (or "km × 5 ÷ 8")
- 1 inch = 2.54 cm exactly
Weight
- 1 kg ≈ 2.2 lb
- 1 lb ≈ 0.45 kg
- 100 g ≈ 3.5 oz
Temperature
- Double the Celsius and add 30 → close to Fahrenheit (25 °C → 80 °F, actual 77 °F)
- (F − 30) / 2 → Celsius
Volume
- 1 US gallon ≈ 3.8 liters
- 1 UK gallon ≈ 4.5 liters (different!)
- 1 cup ≈ 240 mL
For precise values, use our Length, Weight, Temperature, and Volume converters.
Try these calculators