New estimates on the premodern economic growth of Japan, based on more concrete evidence, have been presented. We revise the estimates of Japan’s gross domestic product (GDP) from the mid-eighth century to the mid-19th century and its population in the 12th century and describe the institutional transformations that correspond to the output changes. The revision of output and population results in updated estimates of per capita GDP for the medieval period and extension of the growth estimates in the early modern period to the annual series for 1651–1841. This study employs the techniques of quantitative inference and descriptive interpretation of the estimated performance. The findings show that: (a) Both the GDP and population significantly declined towards the 12th century, stagnated and experienced recovery from the 13th century onwards, and then continued to grow through the 17th century; (b) GDP growth accelerated in the 18th and 19th centuries; and (c) per capita GDP growth began to rise in the 13th century after a sharp decline from the 10th to 12th centuries. It continued to rise through the 16th century but declined again in the mid-17th century and finally rose again from the late 17th century onwards.