Compound interest with monthly contributions
Runs 100% in your browser. Numbers stay on your device.
Most savers do not only park a one-time principal — they add money on a schedule. TryCalculatingNow simulates that path: compound within each month for your chosen frequency, then add the monthly contribution. Educational illustration only.
Starter scenario
$10,000 start · $200/month · 7% annual · monthly compounding · 10 years — open the tool with those params prefilled:
How to read the result
- Final balance — projected account value.
- Total contributed — principal plus every monthly add.
- Interest earned — the gap (balance − contributions).
- Chart — solid line balance vs dashed contributions over years.
Disclaimer: This calculator shows math, not investment advice. Rates change; fees and taxes shrink real results. Confirm against product disclosures before decisions.
Frequently asked questions
How do monthly contributions affect compound interest?
Each month the model compounds for that period, then adds your deposit at month end. Ending balance = cash you put in plus interest on the growing balance. The chart’s contribution line is cash-in; the gap to balance is interest.
What inputs does the calculator need?
Starting principal, monthly contribution, annual rate (%), years, and compounding frequency (daily, monthly, quarterly, or yearly). Shareable URLs use numbers only (p, m, r, y, f).
Is this investment advice?
No. Outputs are educational math. Markets, fees, taxes, and inflation are outside the model. Verify against your institution’s statements when real money is involved.
Are my dollar amounts uploaded?
No. Chart.js is bundled at build time; calculation and drawing stay in your browser. Refresh clears inputs.