» Interest Calculator


Interest calculator for compound and simple interest. Calculate ending balance, regular contributions or withdrawals, interest rate, principal, or time period.

Use this interest calculator to compare compound interest and simple interest with the same starting balance, recurring contribution, rate, and time period. It is built for common questions such as how much will my savings grow, how much interest will I earn, and how much difference does compounding make.

You can enter an initial investment, set recurring deposits, choose contribution timing, and switch between simple and compound interest. The calculator shows the projected ending balance, total principal, total interest, a chart, and a yearly accumulation schedule.

Interest formulas

$$A = P \times \left(1 + \frac{r}{n}\right)^{n t}$$

Input
Interest type 

 
Contribution frequency
Payment timing 
 
%
Compounding frequency 
Result

Using compound interest, the ending balance grows to 23288.95 over 10 years.

Interest type:
Compound interest

Initial investment:
0.00
Total contributions:
0.00
Total principal:
0.00
Total interest:
0.00
Effective annual rate:
0.00%
Ending balance:
0.00
Fig. 1 · Interest breakdown

Interest Calculator FAQ

What is the difference between simple interest and compound interest?

Simple interest is calculated on principal only. Compound interest adds earned interest back to the balance, so future interest is earned on both principal and past interest.

Can this calculator include recurring contributions?

Yes. You can add recurring contributions and choose whether they happen annually, quarterly, or monthly. You can also choose whether they are added at the start or end of each contribution period.

Why does compounding frequency matter?

Compounding frequency affects how often interest is added to the balance in compound mode. More frequent compounding generally results in a slightly higher ending balance, all else being equal.

What does total principal mean here?

Total principal is the sum of your initial investment plus all recurring contributions. It excludes interest, so you can see how much of the ending balance comes from money you added yourself.

When should I use simple interest instead of compound interest?

Use simple interest for basic interest calculations where earnings do not themselves earn interest. Use compound interest for savings, investments, and accounts where interest is periodically added back to the balance.


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