Interest Calculator
Calculate final amount and total interest earned with simple or compound interest.
Note: Results are estimates for educational purposes only. Consult a qualified professional before making financial decisions.
How to use
- Enter the starting principal (your initial deposit or investment).
- Enter the annual interest rate as a percentage.
- Enter the time period in years.
- Choose the compounding frequency (how often interest is added).
- Click Calculate to see the final amount and interest earned.
When people use this
- Estimating savings account growth.
- Comparing investment returns across different compounding schedules.
- Planning for retirement savings goals.
- Understanding how compound frequency affects total returns.
Examples
Savings account. $10,000 at 5% compounded monthly for 10 years grows to $16,470.09 — earning $6,470.09 in interest.
Simple interest comparison. The same $10,000 at 5% simple interest for 10 years gives $15,000 — $1,470.09 less than monthly compounding.
Daily compounding. $5,000 at 4% compounded daily for 5 years becomes $6,107.33, with an effective annual rate of about 4.08%.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is calculated only on the principal. Compound interest adds earned interest back to the balance, so you earn interest on your interest.
How does compounding frequency affect returns?
More frequent compounding gives slightly higher returns — daily beats monthly, which beats annual — but the difference is usually small for typica... [truncated]
Is the interest taxed or net of fees?
No. The result is a gross figure — before tax and any account fees — and it assumes the rate stays constant for the whole period.
What is the effective annual rate?
It is the equivalent yearly growth after compounding. For example, 5% compounded monthly has an effective annual rate of about 5.12%, because interest is added 12 times a year.