Metric to Imperial: A Quick Reference Guide

Length Conversions

Length is the most common conversion need, especially for distance and height:

• 1 millimetre (mm) = 0.0394 inches
• 1 centimetre (cm) = 0.394 inches
• 1 metre (m) = 3.281 feet = 1.094 yards
• 1 kilometre (km) = 0.621 miles = 3,281 feet
• 1 inch = 2.54 cm
• 1 foot = 30.48 cm = 0.305 m
• 1 yard = 91.44 cm = 0.914 m
• 1 mile = 1.609 km = 1,760 yards

Quick km to miles approximation: Multiply by 0.6. So 50 km ≈ 30 miles, 100 km ≈ 60 miles. The exact conversion is 0.621, so the approximation is about 3% low — close enough for most everyday purposes.

Height in feet and inches: To convert cm to feet and inches, divide by 30.48 for feet, then take the decimal part and multiply by 12 for inches. Example: 175 cm ÷ 30.48 = 5.74 feet = 5 feet 8.9 inches.

Weight Conversions

• 1 gram (g) = 0.035 ounces
• 1 kilogram (kg) = 2.205 pounds (lbs)
• 1 metric ton (tonne) = 1,000 kg = 2,205 lbs = 1.102 US tons
• 1 ounce (oz) = 28.35 g
• 1 pound (lb) = 0.454 kg = 453.6 g
• 1 stone = 14 lbs = 6.35 kg
• 1 US ton (short ton) = 2,000 lbs = 907 kg

Quick kg to lbs: Multiply by 2.2. So 80 kg ≈ 176 lbs. For the reverse, divide lbs by 2.2 (or multiply by 0.454).

Temperature Conversions

Temperature is unique because it requires a formula rather than simple multiplication:

• Celsius to Fahrenheit: °F = (°C × 9/5) + 32
• Fahrenheit to Celsius: °C = (°F − 32) × 5/9
• Celsius to Kelvin: K = °C + 273.15

Key reference points:

• 0°C = 32°F (water freezes)
• 20°C = 68°F (comfortable room temperature)
• 37°C = 98.6°F (average human body temperature)
• 100°C = 212°F (water boils at sea level)
• −40°C = −40°F (the one point where the two scales agree)

Quick Celsius approximation: Double the Celsius value and add 30. At 20°C, this gives 70°F (actual: 68°F) — accurate to within a few degrees for normal temperature ranges.

Volume Conversions

• 1 millilitre (ml) = 0.034 US fluid ounces
• 1 litre (L) = 1.057 US quarts = 0.264 US gallons = 2.113 US pints
• 1 US teaspoon = 4.93 ml
• 1 US tablespoon = 14.79 ml
• 1 US cup = 236.6 ml
• 1 US fluid ounce = 29.57 ml
• 1 US pint = 473 ml
• 1 US quart = 946 ml
• 1 US gallon = 3.785 litres
• 1 UK pint = 568 ml (note: different from US pint)

Speed Conversions

• 1 km/h = 0.621 mph
• 1 mph = 1.609 km/h
• 1 m/s = 3.6 km/h = 2.237 mph
• 1 knot = 1.852 km/h = 1.151 mph

For quick driving speed reference: 60 mph ≈ 97 km/h, 100 km/h ≈ 62 mph, 70 mph ≈ 113 km/h.

Using the Online Unit Converter

For precise conversions across all these categories and more — including area, energy, pressure, and fuel efficiency — our Unit Converter handles everything instantly in your browser. Select your category, enter the value, and all conversions appear simultaneously.

Frequently Asked Questions

How do you convert km to miles?

Multiply kilometres by 0.621371 to get miles. Quick approximation: multiply by 0.6 for a rough estimate. So 10 km ≈ 6.2 miles, 100 km ≈ 62 miles. For the reverse, multiply miles by 1.60934 to get kilometres.

How do you convert Celsius to Fahrenheit?

Formula: °F = (°C × 9/5) + 32. Quick mental estimate: double the Celsius temperature and add 30 (accurate to within a few degrees for normal temperatures). Examples: 0°C = 32°F (freezing), 20°C = 68°F (comfortable room temperature), 100°C = 212°F (boiling).

How many kg are in a pound?

One pound equals approximately 0.4536 kg. One kilogram equals approximately 2.2046 pounds. Quick approximation: 1 kg ≈ 2.2 lbs. So 70 kg ≈ 154 lbs, and 150 lbs ≈ 68 kg.

Which countries still use imperial units?

The United States, Liberia, and Myanmar are the only countries that have not officially adopted the metric system as their primary measurement system. The UK uses a mix — metric for most official purposes but miles for road distances and pints for beer.