Fill in a starting principal, a monthly contribution, an annual rate, a term, and how often interest compounds, and the projected final balance redraws as you go.
- Enter the starting principal and the monthly contribution.
- Enter the annual interest rate and the number of years.
- Pick a compounding frequency: monthly, annually, or daily.
- Read the final value, total contributed, and interest earned - they update automatically, no button to click.
Compound Interest Calculator
Wondering what a monthly saving habit is really worth years from now? This projects a starting amount plus a fixed monthly contribution forward at a compound rate you choose, so you can sanity-check a long-term plan before committing to it.
Key features
- Enter the starting principal, monthly contribution, annual rate, term, and compounding frequency; the final value, total contributed, and interest earned update as you type - there is no submit button.
- Every number you type - principal, rate, compounding choice - is read directly from the form and projected forward in this tab, without a round trip to any server or a login screen.
- The total you contributed is shown next to the interest earned, so you can read at a glance how much of the ending balance is money you paid in versus growth the compounding added on top - the gap between the two figures is a quick measure of what the rate and term are actually earning you.
When to use it
Use it to see what a balance becomes after a set number of years, or to compare how monthly against annual compounding changes the final figure. The frequency selector also offers a daily option alongside monthly and annual, and each choice re-prices your monthly contribution into a matching per-period amount before the projection is calculated. Switching between the three lets you see how the schedule on which interest is applied - twelve times a year, once a year, or every day - nudges the same principal and rate to a different final figure.
What the output is
Output is a single USD figure with no growth chart or export - for a jurisdiction-specific plan that accounts for taxes and inflation, use this as a quick sanity check, then talk to a licensed advisor.
Because this projection applies one fixed rate across the whole term, the ending balance traces a smooth best-case curve; a real account earns a rate that shifts year to year, so read the final USD figure as a planning benchmark for how the principal, contributions, and compounding frequency interact rather than a guaranteed outcome, and this is not financial advice.
Frequently Asked Questions
What does Compound Interest Calculator do?
Project how a starting balance and regular contributions grow with compound interest over time.
When should I reach for compound interest calculator?
Reach for it when you want to see how a starting principal plus a monthly contribution grows once compounding is applied each period. Enter your principal, monthly contribution, annual interest rate, and term in years, and it returns the final value, total contributed, and interest earned, recalculated live as you change any field.
Does this account for taxes or inflation?
No. Results are an estimate based on a constant rate; they do not account for taxes, inflation, or fees, and this is not financial advice.
Is anything I type uploaded or saved?
No. The math runs locally in the browser - no upload, no account, and nothing is stored beyond the current page session.