Compound interest

Japanese

複利

Last reviewed

September 24, 2026

This is a draft, shown for review before publication.

Compound interest is a way of calculating interest in which interest is added to the principal and the next period's interest is charged on that total. Because interest also earns interest, at the same rate the amount ends up larger than under simple interest, which charges interest only on the principal. The gap widens as the period gets longer.