Compound Interest Calculator
Calculate how your money can grow with compound interest and regular contributions.
Compound interest calculator
Future Value
$37,315.12
- Starting amount
- $10,000.00
- Total contributions
- $12,000.00
- Interest earned
- $15,315.12
How it works
Compound interest means you earn interest on both your original amount and previously earned interest. The more often interest compounds, the more frequently earned interest becomes part of the balance.
The basic lump-sum relationship is:
A = P(1 + r/n)nt
- A = final amount
- P = starting principal
- r = annual interest rate
- n = compounding periods per year
- t = number of years
Regular contributions extend the calculation beyond that lump-sum expression. Each contribution is added at the end of its monthly or yearly period and then earns interest for the time that remains.
- Starting amount:
- $10,000.00
- Interest rate:
- 7%
- Period:
- 10 years
- Regular contribution:
- $100.00 monthly
- Compounding:
- Annually
- Future value:
- $37,315.12
- Interest earned:
- $15,315.12
Questions
What is compound interest?
Compound interest is interest calculated on both the starting amount and the interest already added to the balance. Over time, that can make the balance grow faster than simple interest.
How is compound interest calculated?
The calculator applies the stated annual rate at the selected compounding frequency. Regular contributions are added at the end of each contribution period, then continue to earn interest for the remaining term.
What is compounding frequency?
Compounding frequency is how often earned interest is added to the balance. This calculator supports annually, semi-annually, quarterly, monthly, and daily.
What is the difference between compound interest and simple interest?
Simple interest is calculated only on the starting amount. Compound interest is calculated on the starting amount plus interest already earned.
How do regular contributions affect the result?
Each contribution is added to the balance at the end of its monthly or yearly period and then earns interest for the time that remains. Monthly contributions are not treated as one lump sum at the end of the year.
Does compounding more often increase the final amount?
When the same nominal annual rate is used, compounding more often usually produces a slightly higher future value because interest is added to the balance more frequently.
Can I use this calculator for savings accounts?
You can enter a starting amount, rate, time, and contributions that match a savings plan. Actual account terms, fees, and rates may differ.
Does this calculator predict actual investment returns?
The calculator demonstrates mathematical growth using the rate entered by the user. It does not predict future investment performance.