What is the interest calculator?
In short
Compound interest re-applies your rate to a growing balance, so it earns more than simple interest (I = P × r × t) over time. For example, $20,000 at 4.5% compounded monthly for 5 years earns about $5,030 in interest, for a final balance of roughly $25,030. KalkWise shows total interest separately from your deposits so you can see growth clearly.
This interest calculator shows how much interest you earn on savings or deposits over time. Enter a balance, a rate, and a period, and optionally add regular contributions to see total interest earned.
How to use this calculator
- 1Enter your starting balance.
- 2Set the annual interest rate and compounding frequency.
- 3Choose the time period in years and months.
- 4Optionally add regular deposits.
- 5See total interest earned and the final balance.
The formula
- FV
- — Final amount
- P
- — Principal
- PMT
- — Periodic deposit
- r
- — Annual rate (decimal)
- n
- — Compounds per year
- t
- — Years
KalkWise uses compound interest by default, which reflects how most savings and investment accounts actually work. Simple interest would instead be I = P × r × t.
Worked example
The scenario
Deposit $20,000 at 4.5% compounded monthly for 5 years, no further deposits.
The result
You earn about $5,030 in interest, for a final balance of roughly $25,030.
Common use cases
- Estimating interest on a high-yield savings account
- Comparing savings account rates
- Checking interest earned on a fixed deposit or CD
- Understanding how compounding boosts returns
Limitations & assumptions
- Assumes a fixed rate; promotional and variable rates change over time.
- Excludes taxes on interest income.
- Does not model early-withdrawal penalties on fixed deposits.
Frequently asked questions
What is the difference between simple and compound interest?
Is savings account interest compounded?
Is interest taxable?
Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.