Unit Converter UK
Free Unit UK | Metric & Imperial Conversion Calculator converter — fast, accurate and easy to use. Convert between common units instantly with our online...
Last updated: February 2026
Unit Converter UK
Convert between UK imperial and metric units instantly. Our comprehensive calculator handles length, weight, volume, temperature, and area conversions commonly used in the United Kingdom.
Length Converter
UK Measurement System Explained
The United Kingdom uses a unique hybrid measurement system. While officially metric since the Weights and Measures Act 1985, imperial units remain deeply embedded in daily life. This dual system reflects the UK's gradual transition from imperial measurements—based on the Weights and Measures Act 1824—to the metric system adopted across the European Union.
Legal Imperial Units in the UK (2024): Road distances and speed limits (miles, mph), draught beer and cider in pubs (pints), milk in returnable containers, precious metals (troy ounces), and body weight (stones and pounds informally). Since 2022, shops may display imperial units alongside metric.
Metric-Only Areas: All packaged goods, scientific measurements, medical prescriptions, building materials, and official trade. The metric system is taught exclusively in UK schools.
Quick Reference Tables
Common Length Conversions
| Imperial UK | Metric Metric | Common Use |
|---|---|---|
| 1 inch | 2.54 cm | Screen sizes, rainfall |
| 1 foot | 30.48 cm | Height, room dimensions |
| 1 yard | 0.9144 m | Fabric, sports |
| 1 mile | 1.60934 km | Road distances |
| 5 miles | 8.047 km | 5K race equivalent |
| 26.2 miles | 42.195 km | Marathon |
Common Weight Conversions
| Imperial UK | Metric Metric | Common Use |
|---|---|---|
| 1 ounce (oz) | 28.35 g | Recipes, precious metals |
| 1 pound (lb) | 453.59 g | Baby weight, groceries |
| 1 stone (st) | 6.35 kg | Body weight |
| 14 stone | 88.9 kg | Average UK man |
| 10 stone | 63.5 kg | Average UK woman |
| 1 UK ton (long) | 1016.05 kg | Shipping, heavy loads |
Common Volume Conversions
| Imperial UK | Metric Metric | Common Use |
|---|---|---|
| 1 UK fluid ounce | 28.41 ml | Cooking, spirits |
| 1 UK pint | 568.26 ml | Beer, milk |
| 1 UK gallon | 4.546 litres | Fuel efficiency |
| 1 US pint | 473.18 ml | American recipes |
| 1 US gallon | 3.785 litres | US fuel prices |
| 2 UK pints | 1.137 litres | Milk cartons |
Important: UK pints are 20% larger than US pints. This affects cooking and fuel economy comparisons.
Temperature Reference Points
| Description | Celsius (°C) | Fahrenheit (°F) |
|---|---|---|
| Water freezing point | 0°C | 32°F |
| Cold winter day (UK) | 2°C | 36°F |
| Cool spring day | 10°C | 50°F |
| Room temperature | 20°C | 68°F |
| Hot summer day (UK) | 30°C | 86°F |
| Body temperature | 37°C | 98.6°F |
| Water boiling point | 100°C | 212°F |
| Gas Mark 4 (oven) | 180°C | 350°F |
| Gas Mark 6 (oven) | 200°C | 400°F |
Area Conversions for Property
| Imperial UK | Metric Metric | Context |
|---|---|---|
| 1 square foot | 0.0929 m² | Room sizes |
| 100 sq ft | 9.29 m² | Small bedroom |
| 818 sq ft | 76 m² | Average UK home |
| 1,076 sq ft | 100 m² | Larger house |
| 1 acre | 4,047 m² | Land/gardens |
| 1 hectare | 10,000 m² | Farming land |
| 1 square mile | 2.59 km² | Town/city area |
UK Speed Limit Reference
| Location | Speed (mph) | Speed (km/h) |
|---|---|---|
| Built-up areas (default) | 30 mph | 48 km/h |
| Single carriageway | 60 mph | 97 km/h |
| Dual carriageway | 70 mph | 113 km/h |
| Motorway | 70 mph | 113 km/h |
| 20 mph zones | 20 mph | 32 km/h |
Tip: When driving in Europe, multiply mph by 1.6 to get km/h. The UK is one of only three countries worldwide (with USA and Myanmar) still using mph on roads.
7 Tips for UK Unit Conversions
- Remember the "5-8" rule for miles: 5 miles ≈ 8 kilometres. This makes mental conversions easy—just multiply miles by 1.6 or km by 0.6.
- Use body weight landmarks: 10 stone = 63.5 kg (140 lbs), 12 stone = 76 kg (168 lbs), 14 stone = 89 kg (196 lbs). Most UK adults know their weight in stones.
- Know pint sizes for beer abroad: A UK pint is 568ml, but in the US you'll get only 473ml. European countries use 500ml or 330ml glasses—not official pints.
- Convert cooking temperatures quickly: For oven temperatures, Gas Mark × 25 + 125 = °C. Example: Gas Mark 6 = (6 × 25) + 125 = 275°C (close to actual 200°C).
- Estate agent tip: UK properties list area in both m² and sq ft. To convert sq ft to m², divide by roughly 11 (actual: 10.764).
- Fuel economy confusion: UK mpg is about 20% higher than US mpg for the same car because UK gallons are larger. A car doing 40 UK mpg = 33 US mpg.
- Height conversion: 5'0" = 152cm, 5'6" = 168cm, 6'0" = 183cm. Add 2.5cm per inch and 30cm per foot.
7 Common Unit Conversion Mistakes
- Confusing UK and US pints/gallons: The UK pint (568ml) is 20% larger than the US pint (473ml). Always specify which system you're using, especially for recipes.
- Forgetting stones have 14 pounds: Many people incorrectly assume 10 pounds per stone. The correct conversion is 1 stone = 14 pounds = 6.35 kg.
- Using US fluid ounces for UK recipes: UK fl oz = 28.41ml vs US fl oz = 29.57ml. While close, this can affect baking precision over multiple measurements.
- Mixing metric tonnes and UK tons: A metric tonne = 1,000 kg, but a UK long ton = 1,016 kg. This 1.6% difference matters in shipping and industry.
- Assuming temperature conversion is simple: People often try to halve/double Fahrenheit for Celsius. The correct formula is °C = (°F - 32) × 5/9.
- Ignoring the square for area: Converting 10 feet to metres (3.048m) doesn't mean 10 sq ft = 3.048 m². It's actually 0.929 m² (multiply by 0.0929).
- Using American cooking measurements: A US cup = 237ml, but a UK cup = 284ml. American recipes need adjustment for UK kitchens.
Frequently Asked Questions
Official UK Resources
National Measurement Office
Part of the Department for Business and Trade, responsible for UK measurement policy and enforcement.
GOV.UK - Weights & Measures →National Physical Laboratory
The UK's National Metrology Institute, responsible for measurement science and standards.
NPL - National Standards →Weights and Measures Act
The primary legislation governing units of measurement for trade in the UK.
Legislation.gov.uk →RICS Property Measurement
Royal Institution of Chartered Surveyors standards for measuring property floor areas.
RICS Property Standards →Met Office
UK's national weather service using Celsius for all temperature measurements and forecasts.
Met Office Weather →British Beer & Pub Association
Information on UK beer measures and the legal requirement for pint glasses.
BBPA - UK Pubs →Related Calculators
About This Unit Converter
This comprehensive UK unit converter is designed specifically for British users who regularly need to convert between imperial and metric measurements. Whether you're calculating your weight for a medical appointment, converting a recipe from an American cookbook, understanding property floor areas, or comparing fuel efficiency between UK and US vehicles, our calculator provides instant, accurate results.
All conversions use the official conversion factors defined by the UK Weights and Measures Act 1985 and international SI standards. The calculator distinguishes between UK imperial and US customary units—a crucial difference often overlooked by generic converters. For example, we correctly calculate that a UK pint equals 568.261ml (not the US 473ml), and a UK gallon equals 4.546 litres (not the US 3.785 litres).
Created and maintained by UK Calculator, this tool is part of the UK Calculator suite—free, privacy-focused calculators designed specifically for United Kingdom residents. All calculations are performed locally in your browser; no data is sent to any server.
Last updated: February 2026 | Verified with latest UK rates
Pro Tips for Accurate Results
- Double-check your input values before calculating
- Use the correct unit format (metric or imperial)
- For complex calculations, break them into smaller steps
- Bookmark this page for quick future access
Understanding Your Results
Our Unit Converter provides:
- Instant calculations - Results appear immediately
- Accurate formulas - Based on official UK standards
- Clear explanations - Understand how results are derived
- 2025/26 updated - Using current rates and regulations
Common Questions
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Yes, all our calculators are 100% free to use with no registration required.
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Our calculators use verified formulas and are regularly updated for accuracy.
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