Imperial to Metric Conversion - Complete Guide
Length | Weight | Volume | Temperature
The most common UK conversions are 1 stone = 6.35029 kg, 1 pound = 0.453592 kg, 1 foot = 30.48 cm, and 1 imperial pint = 568.261 ml. Use the tables below for weight, length, volume and temperature conversions, including the reverse direction where useful.
Why Do We Still Use Imperial Measurements in the UK?
The United Kingdom officially adopted the metric system for trade and legal purposes during the 1970s and 1980s. Road signs remain in miles, pints are still served in pubs, and most adults think of their height in feet and inches and their body weight in stone and pounds. The result is a country that uses both systems simultaneously - metric in official settings, imperial in everyday life.
Understanding how to convert between the two is a practical skill used daily across health, travel, cooking, sport, and construction. This page covers every major imperial-to-metric conversion you are likely to need.
Weight Conversions - Imperial to Metric
| Imperial Unit | Exact Metric Equivalent | Quick Estimate |
|---|---|---|
| 1 ounce (oz) | 28.3495 grams | About 28 g |
| 1 pound (lb) | 0.453592 kg | About 454 g |
| 1 stone | 6.35029 kg | About 6.35 kg |
| 1 stone | 14 pounds exactly | - |
| 1 hundredweight (cwt) | 50.8023 kg | About 51 kg |
| 1 imperial ton | 1,016.05 kg | About 1 tonne |
| 14 lbs | 6.35029 kg (1 stone) | - |
| 1 kg (Metric to Imperial) | 2.20462 lbs | About 2 lbs 3 oz |
The weight conversion most UK adults need daily
- Stone to kg: multiply stone by 6.35029. Example: 11 stone = 11 × 6.35 = 69.85 kg.
- Kg to stone: divide kg by 6.35029. Example: 70 kg ÷ 6.35 = 11.02 stone = 11 stone 0 pounds.
- Pounds to kg: multiply lbs by 0.453592. Example: 154 lbs × 0.454 = 69.93 kg.
- Kg to pounds: multiply kg by 2.20462. Example: 70 kg × 2.20462 = 154.3 lbs.
Length Conversions - Imperial to Metric
| Imperial Unit | Exact Metric Equivalent | Quick Estimate |
|---|---|---|
| 1 inch (in) | 2.54 cm exactly | About 2.5 cm |
| 1 foot (ft) | 30.48 cm exactly | About 30 cm |
| 1 yard (yd) | 0.9144 metres exactly | About 0.91 m |
| 1 mile | 1.60934 km | About 1.6 km |
| 1 nautical mile | 1.852 km exactly | About 1.85 km |
| 5ft 6in (UK avg height) | 167.64 cm | About 168 cm |
| 6ft 0in | 182.88 cm | About 183 cm |
| 1 cm (Metric to Imperial) | 0.393701 inches | About 0.4 inches |
To convert feet and inches to centimetres: multiply total inches by 2.54. Example: 5ft 6in = 66 inches × 2.54 = 167.64 cm. To convert centimetres to inches, divide by 2.54.
Volume Conversions - Imperial to Metric
| Imperial Unit | Exact Metric Equivalent | Quick Estimate |
|---|---|---|
| 1 fluid ounce (fl oz) | 28.4131 ml | About 28 ml |
| 1 pint (pt) | 568.261 ml | About 568 ml |
| 1 quart | 1,136.52 ml (1.137 L) | About 1.14 L |
| 1 gallon (UK) | 4.54609 litres | About 4.5 L |
| 1 US gallon | 3.78541 litres | About 3.8 L |
| 1 litre (Metric to Imperial) | 1.75975 UK pints | About 1.76 pints |
| 1 litre | 0.21997 UK gallons | About 0.22 gallons |
Note: UK imperial pints and gallons differ from US measurements. A UK pint is 568 ml; a US pint is 473 ml. A UK gallon is 4.546 L; a US gallon is 3.785 L. Always specify which system when converting volumes for cooking or fuel calculations.
Temperature Conversion - Fahrenheit to Celsius
To convert Fahrenheit to Celsius: subtract 32, then multiply by 5/9. To convert Celsius to Fahrenheit: multiply by 9/5, then add 32.
| Fahrenheit (°F) | Celsius (°C) | Context |
|---|---|---|
| 32°F | 0°C | Water freezes |
| 98.6°F | 37°C | Normal body temperature |
| 100°F | 37.8°C | Mild fever threshold |
| 212°F | 100°C | Water boils |
| 350°F | 177°C | Typical baking temperature |
| 68°F | 20°C | Comfortable room temperature |
| 0°F | -17.8°C | Extreme cold reference |
How UK Adults Use Both Systems Day to Day
Most UK adults navigate both systems without thinking about it. They buy petrol in litres, drive distances in miles, order a pint in a pub, buy food in grams and kilograms, give their height in feet and inches, and weigh themselves in stone and pounds. Temperature is usually given in Celsius on weather forecasts, though older adults often convert to Fahrenheit mentally.
The clearest everyday example is body weight. The NHS/WHO records and measures in kilograms. Bathroom scales show stone, lbs, and kg. Most adults know their weight in stone but need the kg figure for a GP appointment, a fitness app, or an international health service. This site exists precisely to make that conversion instant and accurate.
Why metric matters in health settings
UK health records and clinical calculations commonly use metric units: medication may be expressed in milligrams, blood results in millimoles per litre, height in centimetres and weight in kilograms. Converting a stone or pound value to kilograms helps keep a health conversation clear, but a conversion alone does not assess health or diagnose a condition.
FAQs
How do I convert imperial to metric for weight?
Multiply pounds by 0.453592 to get kilograms. Multiply stone by 6.35029 to get kilograms. Multiply ounces by 28.3495 to get grams.
How do I convert feet and inches to centimetres?
Multiply total inches by 2.54. Example: 5ft 8in = 68 inches. 68 × 2.54 = 172.72 cm.
How many ml in an imperial pint?
One UK imperial pint is 568.261 ml. The US pint is 473.176 ml - always specify which system.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5 divided by 9. Example: 98.6°F minus 32 = 66.6, times 5/9 = 37°C.
Why does the UK still use imperial measurements?
The UK adopted metric officially in the 1970s and 80s but imperial units remain in everyday use - miles on road signs, pints in pubs, stone and pounds for body weight. Both systems coexist in UK daily life.
Dr Muhammad Usman
Dr Muhammad Usman graduated with his MBBS from Avicenna International Medical University in Bishkek, Kyrgyzstan (2019–2024).
He brings clinical training across general medicine, surgery, and public health, and writes the site's health information for UK readers in clear, practical language.