Conversion Calculator: Units & Measurements Guide
Convert between any units: length, weight, volume, temperature, and more. Full guide with metric vs imperial tables and conversion formulas.
Conversion Calculator — Direct Answer
Unit conversion multiplies by a conversion factor. 1 inch = 2.54 cm. 1 kg = 2.205 lb. 1 mile = 1.609 km. 1 gallon = 3.785 L. Temperature uses formulas instead of multiplication: °F = (°C × 9/5) + 32.
→ Convert any units with our free conversion calculator
How to Convert Units
Multiply by a conversion factor for most units. Temperature uses formulas.
Length conversion
1 inch = 2.54 cm
1 foot = 30.48 cm
1 yard = 0.9144 m
1 mile = 1.609 km
Example: 10 miles to km
- 10 × 1.609 = 16.09 km
Weight conversion
1 ounce = 28.35 g
1 pound = 0.4536 kg
1 stone = 6.35 kg
1 ton (US) = 0.907 metric tons
Example: 150 lb to kg
- 150 × 0.4536 = 68.04 kg
Volume conversion
1 teaspoon = 4.93 mL
1 cup = 236.6 mL
1 pint = 473.2 mL
1 gallon = 3.785 L
1 cubic foot = 28.317 L
Example: 5 gallons to liters
- 5 × 3.785 = 18.93 L
Temperature conversion
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
Example: 25°C to °F
- (25 × 1.8) + 32 = 77°F
Unit Conversion Charts
Length conversions
| From | To | Multiply by |
|---|---|---|
| Inches | cm | 2.54 |
| Feet | m | 0.3048 |
| Yards | m | 0.9144 |
| Miles | km | 1.6093 |
| cm | inches | 0.3937 |
| m | feet | 3.2808 |
| km | miles | 0.6214 |
Weight conversions
| From | To | Multiply by |
|---|---|---|
| Ounces | grams | 28.35 |
| Pounds | kg | 0.4536 |
| kg | pounds | 2.2046 |
| Stones | kg | 6.3503 |
| Metric tons | US tons | 1.1023 |
Volume conversions
| From | To | Multiply by |
|---|---|---|
| mL | fl oz | 0.0338 |
| L | gallons | 0.2642 |
| Gallons | L | 3.7854 |
| Cups | mL | 236.59 |
| Cubic feet | gallons | 7.4805 |
Temperature reference
| °C | °F | Notes |
|---|---|---|
| 0 | 32 | Freezing |
| 10 | 50 | Cool |
| 20 | 68 | Room temp |
| 25 | 77 | Warm |
| 30 | 86 | Hot |
| 37 | 98.6 | Body temp |
| 100 | 212 | Boiling |
Common Conversion Mistakes
Mistake 1: Using the wrong direction
Multiplying by 2.54 converts inches to cm. To go cm to inches, divide by 2.54.
Fix: Check: does your answer make sense? 10 inches ≈ 25 cm (not 4 cm).
Mistake 2: Temperature uses formulas, not multiplication
°C × 2 = °F is wrong. Use (°C × 1.8) + 32.
Fix: Use the correct formula. Only temperature uses offset math.
Mistake 3: Mixing up US and UK units
US gallon = 3.785 L. UK gallon = 4.546 L. 20% difference.
Fix: Confirm US vs UK units for gallons, ounces, pints.
Unit System Overview
Metric system (SI)
- Base units: meter, kilogram, liter, second
- Prefixes: kilo (1000), centi (0.01), milli (0.001)
- Use: Everywhere except US
Imperial / US customary
- Base units: foot, pound, gallon, second
- Not decimal-based (12 inches per foot, 16 oz per lb)
- Use: US, parts of UK
Key differences
| Metric | Imperial |
|---|---|
| Meter | Foot (0.3048 m) |
| Kilogram | Pound (0.4536 kg) |
| Liter | Gallon (3.785 L) |
| Celsius | Fahrenheit |
Conversion Calculator FAQ
How do I convert units?
Multiply by the conversion factor. For length, weight, and volume, use the factor from the chart above.
How do I convert Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. 25°C = 77°F.
How many cm in an inch?
2.54 cm. 10 inches = 25.4 cm.
How many pounds in a kilogram?
2.2046 lb. 10 kg = 22.05 lb.
How do I convert miles to kilometers?
Multiply by 1.6093. 5 miles = 8.05 km.
Next Steps for Unit Conversion
- Conversion Calculator — All units
- Temperature Converter — °C/°F/K
- Length Converter — Length units
- Celsius to Fahrenheit Guide — Temp formula
- Tire Size Guide — Tire conversion
Last updated October 2026. US and UK units differ for gallons, ounces, and pints.