The best-selling book of all time is the Christian Bible. It is impossible to know exactly how many copies have been printed in the roughly 1500 years since its contents were standardized, but research conducted by the British and Foreign Bible Society in 2021 suggests that the total number probably lies between 5 and 7 billion copies.
Before the advent of the printing press, the number of Bibles in the world was very small. Even though it was the most common book in the Christian world, the enormous outlay of time and money required to reproduce such a large book by hand meant that complete editions were extremely rare and valuable.
This began to change with the development of printing technology in the mid-1400s. In the 50 years that followed the Gutenberg Bible in 1454, it has been estimated that European printers produced 15 million books, the majority of which were Bibles. As technology improved and literacy rates increased, so to did the rate or Bible production. By 1815, the total number of Bibles printed numbered around 1.3 billion.
One key milestone in the history of the Bible comes in the early 19th century, when the first Bible Societies were founded. These organizations ordered Bibles in huge numbers, but gave them away or sold them at cost as part of their Christian mission. From this point on, the majority of Bibles were freely distributed rather than sold. A study produced by the British and Foreign Bible Society (founded in 1804) calculated that 2,458,000,000 Bibles were printed between 1815 and 1975.
The 5–7 billion figure has been arrived at by adding the above-mentioned figures to annual estimates compiled by United Bible Societies (the global umbrella organization). In the 21st century, Bibles are printed at a rate of around 80 million per year.