Unit Conversion Guide: Length, Weight, Temperature and More

Why Unit Conversions Matter

Unit conversions are needed every day — cooking from a recipe in cups when you only have metric scales, travelling and reading road signs in miles, understanding a weather forecast in Fahrenheit, or working with international colleagues using different measurement systems.

The metric system (SI units) is used in most of the world. The imperial system is still used in the United States and partially in the United Kingdom. Understanding both and converting between them is a practical life skill.

Our conversion calculators make any conversion instant: Length | Weight | Temperature | Volume

Length Conversions

Key conversions:

• 1 inch = 2.54 centimetres
• 1 foot = 30.48 centimetres = 0.3048 metres
• 1 yard = 0.9144 metres
• 1 mile = 1.60934 kilometres
• 1 kilometre = 0.62137 miles
• 1 metre = 3.28084 feet = 39.3701 inches
• 1 centimetre = 0.393701 inches

Quick reference — kilometres to miles:

• 1 km = 0.62 miles
• 5 km = 3.1 miles
• 10 km = 6.2 miles
• 21 km (half marathon) = 13.1 miles
• 42 km (marathon) = 26.2 miles
• 100 km = 62.1 miles

Quick reference — feet/inches to centimetres:

• 5'0" = 152.4 cm
• 5'4" = 162.6 cm
• 5'6" = 167.6 cm
• 5'8" = 172.7 cm
• 5'10" = 177.8 cm
• 6'0" = 182.9 cm
• 6'2" = 187.9 cm

Formula shortcuts:

• Miles to km: multiply by 1.609 (or roughly: multiply by 8, divide by 5)
• Km to miles: multiply by 0.621 (or roughly: multiply by 5, divide by 8)
• Inches to cm: multiply by 2.54
• Cm to inches: divide by 2.54

Weight Conversions

Key conversions:

• 1 kilogram = 2.20462 pounds
• 1 pound = 0.453592 kilograms
• 1 stone = 14 pounds = 6.35029 kilograms
• 1 ounce = 28.3495 grams
• 1 gram = 0.035274 ounces
• 1 metric tonne = 1,000 kg = 2,204.62 pounds

Quick reference — kg to pounds:

• 50 kg = 110.2 lbs
• 60 kg = 132.3 lbs
• 70 kg = 154.3 lbs
• 75 kg = 165.3 lbs
• 80 kg = 176.4 lbs
• 90 kg = 198.4 lbs
• 100 kg = 220.5 lbs

Quick reference — kg to stones and pounds:

• 60 kg = 9 st 6 lbs
• 70 kg = 11 st 0 lbs
• 75 kg = 11 st 11 lbs
• 80 kg = 12 st 8 lbs
• 90 kg = 14 st 2 lbs
• 100 kg = 15 st 10 lbs

Formula shortcut:

• Kg to lbs: multiply by 2.205 (quick estimate: double it and add 10%)
• Lbs to kg: multiply by 0.454 (quick estimate: halve it and subtract 10%)

Temperature Conversions

Temperature is the most commonly misunderstood conversion because the formulas are not simple multiplications.

Formulas:

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

Quick reference — Celsius to Fahrenheit:

• −10°C = 14°F (very cold winter day)
• 0°C = 32°F (freezing point of water)
• 10°C = 50°F (cold autumn day)
• 20°C = 68°F (mild spring day)
• 25°C = 77°F (warm summer day)
• 30°C = 86°F (hot day)
• 37°C = 98.6°F (normal body temperature)
• 100°C = 212°F (boiling point of water)

Oven temperatures — Celsius to Fahrenheit to Gas Mark:

• 150°C = 300°F = Gas Mark 2
• 180°C = 350°F = Gas Mark 4
• 200°C = 400°F = Gas Mark 6
• 220°C = 425°F = Gas Mark 7
• 230°C = 450°F = Gas Mark 8

Quick mental conversion:

• °C to °F: double it and add 30 (approximate)
• °F to °C: subtract 30 and halve it (approximate)

These give rough estimates. For accuracy use our Temperature Converter.

Volume Conversions

Volume conversions are especially important in cooking and baking where precise measurements affect results.

Key conversions:

• 1 litre = 1.75975 UK pints = 2.11338 US pints
• 1 UK gallon = 4.54609 litres = 8 UK pints
• 1 US gallon = 3.78541 litres = 8 US pints
• 1 UK pint = 568ml
• 1 US pint = 473ml
• 1 US cup = 236.6ml
• 1 tablespoon (UK) = 15ml
• 1 teaspoon = 5ml
• 1 fluid ounce (US) = 29.57ml

Cooking quick reference:

• 1 cup = 16 tablespoons = 48 teaspoons = 236.6ml
• ¾ cup = 12 tablespoons = 177ml
• ½ cup = 8 tablespoons = 118ml
• ¼ cup = 4 tablespoons = 59ml
• 1 tablespoon = 3 teaspoons = 15ml
• 1 teaspoon = 5ml

Use our Cooking Converter for any culinary measurement conversion.

Speed Conversions

Key conversions:

• 1 mph = 1.60934 km/h
• 1 km/h = 0.62137 mph
• 1 knot = 1.852 km/h = 1.15078 mph
• 1 m/s = 3.6 km/h = 2.237 mph

Speed limits quick reference:

• 30 mph = 48 km/h
• 50 mph = 80.5 km/h
• 60 mph = 96.6 km/h
• 70 mph = 112.7 km/h
• 100 km/h = 62.1 mph
• 120 km/h = 74.6 mph

Area Conversions

Key conversions:

• 1 square metre = 10.7639 square feet
• 1 square foot = 0.092903 square metres
• 1 acre = 4,046.86 square metres = 0.404686 hectares
• 1 hectare = 10,000 square metres = 2.47105 acres
• 1 square mile = 2.58999 square kilometres = 640 acres

Metric Prefixes: The Building Blocks of the Metric System

Understanding metric prefixes lets you convert within the metric system instantly:

• Kilo (k) = 1,000 × (1 kilometre = 1,000 metres)
• Hecto (h) = 100 ×
• Deca (da) = 10 ×
• Base unit (metre, gram, litre, etc.)
• Deci (d) = 0.1 × (1 decimetre = 0.1 metres)
• Centi (c) = 0.01 × (1 centimetre = 0.01 metres)
• Milli (m) = 0.001 × (1 millimetre = 0.001 metres)
• Micro (μ) = 0.000001 ×

Frequently Asked Questions

• How do I convert kg to lbs?

Multiply kilograms by 2.20462. For a quick estimate, multiply by 2.2. Example: 75 kg × 2.2 = 165 lbs. Use our Weight Converter for exact conversion.

• How do I convert miles to kilometres?

Multiply miles by 1.60934. A quick estimate: multiply by 1.6. Example: 26.2 miles × 1.6 = 41.9 km. Our Length Converter handles any distance conversion.

What is 180 degrees Celsius in Fahrenheit? 180°C = (180 × 9/5) + 32 = 324 + 32 = 356°F. This is a common baking temperature.

How many cups are in a litre? 1 litre = approximately 4.23 US cups or 3.52 metric cups (250ml each). Use our Cooking Converter for precise culinary measurements.

What is the difference between UK and US measurements? UK and US fluid measurements differ significantly. A US pint is 473ml while a UK pint is 568ml. A US gallon is 3.785 litres while a UK gallon is 4.546 litres. US cups (236.6ml) and UK metric cups (250ml) also differ. Always specify which system a recipe uses.

How many grams in an ounce? 1 ounce = 28.3495 grams. For cooking, 1 oz ≈ 28g is a sufficient approximation.