Compound Interest
Compounding applies the rate to the whole balance each year. At 6% for 10 years you end with 1.79× the principal, where simple interest gives only 1.6×.
Your numbers
Final amount
17,908,477
Interest
7,908,477
Total growth
79.1%
Formula
Final amount = Principal × (1 + Annual rate ÷ 100) ^ Years
The gap over simple interest widens sharply with time — compounding gets its power from years more than from the rate.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| PrincipalThe money you put in — the base that earns interest. | 10,000,000 | 0 and up |
| Annual rate (%)Interest quoted per year; the monthly rate is this over 12. | 6 | 0 and up |
| Years (yr)How many years the money stays put; compounding bites harder as this grows. | 10 | 0 and up |
Step by step
Quick reference table
Results when only Principal changes and everything else stays put.
| Principal | Final amount | Interest | Total growth (%) |
|---|---|---|---|
| 5,000,000 | 8,954,238 | 3,954,238 | 79.1 |
| 7,500,000 | 13,431,358 | 5,931,358 | 79.1 |
| 10,000,000 | 17,908,477 | 7,908,477 | 79.1 |
| 15,000,000 | 26,862,715 | 11,862,715 | 79.1 |
| 20,000,000 | 35,816,954 | 15,816,954 | 79.1 |
What each result means
| Result | At default values |
|---|---|
| Final amountPrincipal plus interest — what you get at the end. | 17,908,477 |
| InterestThe interest earned or owed over the period. | 7,908,477 |
| Total growth (%)How much it grew across the whole period, as a percentage. | 79.1 |
Common mistakes
The gap over simple interest widens sharply with time — compounding gets its power from years more than from the rate.
Glossary
- Principal
- The money you put in — the base that earns interest.
- Annual rate
- Interest quoted per year; the monthly rate is this over 12.
- Years
- How many years the money stays put; compounding bites harder as this grows.
- Final amount
- Principal plus interest — what you get at the end.
- Interest
- The interest earned or owed over the period.
- Total growth
- How much it grew across the whole period, as a percentage.
Frequently asked questions
Q. How is Compound Interest calculated?
Final amount = Principal × (1 + Annual rate ÷ 100) ^ Years — Compounding applies the rate to the whole balance each year. At 6% for 10 years you end with 1.79× the principal, where simple interest gives only 1.6×.
Q. Can you walk through an example?
With Principal 10,000,000, Annual rate 6%, Years 10yr, the answer is Final amount 17,908,477.
Q. What do I need to enter?
Enter Principal, Annual rate, Years. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Principal moves the answer to Principal 5,000,000 → Final amount 8,954,238 and Principal 20,000,000 → Final amount 35,816,954. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The gap over simple interest widens sharply with time — compounding gets its power from years more than from the rate.
Related calculators
Tax rates and interest conventions differ by country and product — check your contract for real transactions.