Approximately one quarter of the world's population lived within the British Empire at its peak. Around 1913, roughly 412 million people were under British rule, representing about 23% of the global population—close to one person in four.
The empire's enormous population was concentrated mainly in British India, which included territories corresponding broadly to modern India, Pakistan and Bangladesh. In 1913, British India alone had a population of about 304 million. Other major population centres included parts of Africa, Southeast Asia, the Caribbean and the self-governing dominions such as Canada and Australia.
The empire reached its greatest territorial extent around 1920, after Britain acquired former German and Ottoman territories following the First World War. Estimates vary depending on the year and on which protectorates or dominions are counted, so “one quarter” is a rounded historical figure rather than an exact constant. It describes population under imperial authority, not the proportion of people who were ethnically British.