The deposit
The extra deposit uses the same schedule as compounding. No currency symbol.
Future value
Yearly growth
| Year | Deposits | Interest | Balance |
|---|
What compound interest means here
Compound interest means you earn interest on the interest already added. Put 10 000 at 5% a year: after one year you have 10 500, and the next 5% is calculated on that new total.
How often interest is added is the “compounds per year” field: 1 is once a year, 12 is every month (typical for a savings account), 365 is every day. An extra deposit is optional: that amount is added at the end of each compounding period.
This is a clean calculation — no bank fees and no tax on interest. It is not financial advice.
The compound interest formula
Without extra deposits: A = P × (1 + r/n)^(n×t). P is the start, r the annual rate as a decimal, n how many times a year interest is added, t the years.
Example: 10 000 at 5% for 10 years, monthly (n = 12), no extra deposits → 16 470.09. At 0% the future value is just the start plus any deposits.
P = start, r = yearly rate, n = times per year, t = years
How to calculate compound interest
- Enter the start amount and yearly rate: Any currency. 5 means five percent a year, not 5% each month.
- Choose how often interest is added: Monthly is the usual savings-account setting. Yearly is slower, daily is a little faster.
- Optional extra deposit, then read the table: Leave extra at 0 if you only want the starting sum to grow. The table shows each year.
Frequently asked questions
What does monthly compounding mean?
The yearly rate is split into 12 and added 12 times. 5% a year is not 5% every month.
When is the extra deposit added?
At the end of each compounding period. Monthly plus 100 means 100 twelve times a year.
Is this the same as a loan payment?
Related maths, opposite job: here money grows, a loan shrinks. For a monthly loan payment use the loan calculator.
Is tax on interest included?
No. In many countries deposit interest is taxed. This page is not tax advice.