Unit Converter — Length, Weight & Temperature

Why the UK Uses Both Metric and Imperial

The UK officially adopted the metric system for most purposes but retains imperial measurements in several areas of daily life. Road signs show distances in miles and speed limits in miles per hour. Pubs serve beer in pints. People commonly describe their height in feet and inches and their weight in stone and pounds. Meanwhile, food is sold in grams and kilograms, fabric in metres, and fuel in litres. This hybrid system means conversions are a regular necessity for anyone living in or visiting the UK.

In scientific, medical and most commercial contexts, metric units are standard. Building materials, engineering specifications and pharmaceutical dosages all use metric measurements exclusively. Schools teach the metric system as the primary system, though an understanding of imperial units remains practically useful. Our converter supports both systems across all categories so you can move between them effortlessly.

Most Common UK Conversions

The conversions people look up most frequently in the UK include miles to kilometres (1 mile equals 1.609 km), stone to kilograms (1 stone equals 6.35 kg), feet and inches to centimetres (1 foot equals 30.48 cm), pints to litres (1 pint equals 0.568 litres), Fahrenheit to Celsius (subtract 32, then multiply by 5 and divide by 9) and acres to hectares (1 acre equals 0.405 hectares). Knowing a few of these key ratios helps with quick mental approximations when a calculator is not to hand.

For cooking, the most useful conversions are between tablespoons, millilitres and fluid ounces, and between grams, ounces and cups. Note that cup measurements vary between US and UK standards, with a US cup being 237 ml and an imperial cup being 284 ml. Most UK recipes use grams and millilitres for precision, while many online recipes from the US use cups and Fahrenheit, making conversion essential for accurate results.

When Precision Matters

For everyday purposes, approximate conversions are usually sufficient. However, in contexts such as medication dosing, engineering tolerances, scientific experiments and competitive sports, precision is critical. Always use the full conversion factor rather than a rounded approximation when accuracy matters. Our converter uses precise conversion factors and displays results to an appropriate number of decimal places for each unit type.

For related calculation tools, try our percentage calculator or VAT calculator. For official UK measurement standards and trade regulations, visit GOV.UK.