What are imperial units?
Imperial units are measurement units such as inches, feet, yards, miles, ounces, pounds, stone, pints and gallons. They are still common in everyday UK life, even though metric units are used in many official and retail settings.
Imperial units are a set of measurement units used for length, weight, volume and speed. Common examples include inches, feet, yards, miles, ounces, pounds, stone, pints and gallons.
Imperial units are often compared with the metric system. Metric units usually use decimal steps, while imperial conversions often use fixed relationships such as 12 inches in a foot, 3 feet in a yard and 14 pounds in a stone.
Why imperial units matter
Imperial units still appear in many everyday UK situations. Road distances are shown in miles, speed limits are shown in miles per hour, draught beer is sold in pints, and many people describe height in feet and inches.
That is why a UK-friendly converter needs to support both imperial and metric units clearly. A person might need kilograms to stone, centimetres to inches, litres to pints or miles per hour to kilometres per hour.
Common imperial units
Imperial units are used for different measurement types. Some are still very familiar in UK life, while others are used less often.
| Measurement type | Common imperial units | Everyday example |
|---|---|---|
| Length | inches, feet, yards, miles | Height, screen sizes, road distances |
| Weight | ounces, pounds, stone | Body weight, parcels, older recipes |
| Volume | fluid ounces, pints, gallons | Drinks, fuel comparisons, older measures |
| Speed | miles per hour | UK road speed limits |
Imperial conversion rules
Imperial units do not usually move in tens or hundreds, so the conversion factors can be harder to remember than metric conversions.
1 yard = 3 feet
1 mile = 1,760 yards
1 stone = 14 pounds
1 UK pint = 20 UK fluid ounces
For conversions across different systems, use a conversion factor. For example, inches to centimetres uses 2.54, and miles to kilometres uses 1.609344.
Imperial vs metric units
Imperial and metric units can measure the same real-world quantity, but they use different unit sizes and conversion rules.
| Imperial unit | Metric comparison | Used for |
|---|---|---|
| inch | centimetre | Small lengths and screen sizes |
| foot | metre | Height and room measurements |
| mile | kilometre | Long distances and road travel |
| pound or stone | kilogram | Body weight and mass |
| pint or gallon | litre | Liquids and volume |
For a fuller explanation, see the metric vs imperial units guide.
Imperial conversion examples
Here are simple examples of common imperial conversions:
| Conversion | Calculation | Result |
|---|---|---|
| 5 feet to inches | 5 × 12 | 60 inches |
| 3 stone to pounds | 3 × 14 | 42 pounds |
| 2 miles to yards | 2 × 1,760 | 3,520 yards |
| 4 UK pints to UK fluid ounces | 4 × 20 | 80 UK fluid ounces |
Imperial units in the UK
The UK uses a mixed measurement culture. Metric units are common for packaging, education, medicine and many official measurements, while imperial units still appear in roads, speed limits, height, body weight and pints.
This can create everyday conversion questions. For example, someone buying a product listed in centimetres may want inches, while someone tracking body weight may want kilograms converted to stone and pounds.
Quick answers
| Question | Answer |
|---|---|
| What are imperial units? | Imperial units are measurements such as inches, feet, miles, ounces, pounds, stone, pints and gallons. |
| Are imperial units still used in the UK? | Yes. They are still common for roads, speed limits, height, body weight and pints. |
| What is the difference between metric and imperial? | Metric units are decimal-based, while imperial units use older relationships such as 12 inches in a foot and 14 pounds in a stone. |
| Is a mile imperial? | Yes. A mile is an imperial length unit commonly used for road distances in the UK. |
FAQs
What does imperial units mean?
Imperial units are a set of measurement units including inches, feet, yards, miles, ounces, pounds, stone, pints and gallons.
Is a pound an imperial unit?
Yes. A pound is an imperial unit used for weight. There are 14 pounds in 1 stone.
Is a pint imperial or metric?
A pint is an imperial-style volume unit. In the UK, a pint is commonly used for draught beer, cider and milk in some contexts.
Why are imperial conversions harder?
Imperial conversions often use non-decimal relationships, such as 12 inches in a foot, 3 feet in a yard and 14 pounds in a stone.