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Compound interest calculator

See how a starting amount could grow over time.

Illustration only. No guaranteed returns; excludes fees and tax.

What is this tool?

Model how a starting balance changes when returns are reinvested at a constant rate. This is a scenario calculator for understanding compounding. It does not forecast market performance or account for changing rates over time.

How to use it

  1. Read the input labels and limits below, then choose the operation that matches your task.
  2. Enter the initial balance and an assumed annual percentage rate.
  3. Choose the number of years and compounding frequency.
  4. Calculate and compare scenarios while keeping the assumptions visible.
  5. Check the result against the worked example or original file before copying, downloading or using it elsewhere.

Worked example

With yearly compounding, 1,000 at 5% becomes 1,050 after one year and 1,102.50 after two years. The second year earns interest on the first year’s interest as well as on the starting balance.

Questions & limits

Future value = principal × (1 + annual rate / periods per year) raised to (periods per year × years). No additional contributions are included. A constant return is assumed; real investment returns change.

Does this include regular deposits?

No. It grows only the starting amount using a constant assumed rate and your chosen compounding frequency. Future returns, fees, tax and extra contributions can change the outcome.

Can I use a negative rate?

The input supports certain negative-rate scenarios within its limits. The result still assumes a constant rate throughout; actual gains and losses rarely follow that exact path. Compare several assumptions rather than treating a single projection as a promise.

Comparing scenarios

Keep the original assumptions alongside a result when comparing alternatives. Changing a rate, term or fee can change the conclusion, even if the output looks precise. This tool performs a calculation, not a transaction, and does not verify an offer from another organization. Use consistent units and percentage conventions across your examples. Before making a financial commitment, check the current terms, charges and final figures directly with the relevant provider. A rounded display should not be mistaken for a guaranteed outcome.

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Features & limits

Uses a starting amount, a constant annual rate and a term from 0–100 years. Select annual, monthly or daily compounding. It excludes recurring deposits, fees and taxes and cannot predict investment returns. Rates must be above −100%.

This tool runs in a modern browser with JavaScript enabled. It processes the values or files you enter on your device. Loading the site still makes hosting requests. The separate contact form sends messages to the administrator; it is not part of tool processing. Keep an original copy and inspect any exported result before relying on it.

Frequently asked questions

Can I use a negative rate?

The input supports certain negative-rate scenarios within its limits. The result still assumes a constant rate throughout; actual gains and losses rarely follow that exact path. Compare several assumptions rather than treating a single projection as a promise.

What can I use compound interest calculator for?

Model how a starting balance changes when returns are reinvested at a constant rate. This is a scenario calculator for understanding compounding. It does not forecast market performance or account for changing rates over time.

What are this tool’s limits?

Uses a starting amount, a constant annual rate and a term from 0–100 years. Select annual, monthly or daily compounding. It excludes recurring deposits, fees and taxes and cannot predict investment returns. Rates must be above −100%.

Can I try a worked example?

With yearly compounding, 1,000 at 5% becomes 1,050 after one year and 1,102.50 after two years. The second year earns interest on the first year’s interest as well as on the starting balance.

Do I need an account or upload my input?

No tool account is required. Processing takes place in your browser; your tool input is not sent to the contact inbox. Use a trusted device, keep your originals and avoid including passwords or private credentials in examples.

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