Compound Interest Calculator
Watch your money grow with compound interest
Understand the power of compounding in your finances. Enter your amounts and let the calculator show how your balance builds over time.
AI Summary (non-advisory)
Your AI summary will appear here.
Results
Scenarios
Graph Section
The chart visualizes your projected account balance, broken out by total contributions and interest growth for each period. Switch between line and bar views to compare trends over time.
Disclaimer
Estimates are illustrative and for educational purposes only. This compound interest calculator does not provide financial, investment, tax, or legal advice. Results depend on your inputs and assumptions and may not reflect real-world outcomes. Market returns are uncertain and may be negative, and fees, taxes, and inflation are not included unless explicitly stated. Past performance is not a reliable indicator of future results.
Results Overview
| Total Invested | - |
|---|---|
| Final Value | - |
| After Inflation | - |
| Total Contributions | - |
| Total Interest | - |
Yearly Breakdown
| Year | End Balance | Total Contributions | Total Interest |
|---|---|---|---|
| Run a calculation to see yearly details. | |||
Results explainer
Your results tell a simple story: what you’ve put in so far, what it could grow to, and a quick “today’s dollars” view after inflation. You’ll also see how much comes from your own deposits versus interest so you can tell whether time, rate, or contributions are doing the heavy lifting.
How it works
The calculator runs your numbers through the compound interest formula, adds any regular deposits or withdrawals, and can show a simple “real” view after inflation so you have a feel for today’s buying power.
Inputs used
- Starting balance (principal) and annual interest rate
- Compounding frequency (yearly, quarterly, monthly)
- Recurring deposits or withdrawals and their timing
- Years in the projection and start year
- Optional inflation rate for a simple real-value view
Core formulas
- Future value without contributions: A = P(1 + r/n)^(n·t)
- With deposits/withdrawals: cash flows compounded on the same schedule as the base balance
- Illustrative real value: future value ÷ (1 + inflation)^years
Calculation steps
- Normalize the annual rate and compounding frequency to periods per year.
- Add per-period deposits and subtract withdrawals based on your schedule.
- Apply the compound factor across total periods to grow the balance.
- Sum contributions to show total invested and separate interest earned.
- Optionally divide by (1 + inflation)^years for an illustrative real-value view.
- Render yearly rows, summary totals, and the chart from these figures.
Example scenario
Start with $10,000, add $300 a month, earn 6% a year (monthly compounding), and let it run for 15 years. You’d put in about $64,000 total. The projection lands near $97,000, with roughly $33,000 from growth. Turn on a 2% inflation view and it’s closer to $72,000 in today’s terms. Play with rate, contribution, or timeline to see how the interest slice shifts.
Interpretation notes
- Earlier or bigger deposits can matter more than a tiny rate bump.
- The inflation toggle is a rough guide; everyone’s spending mix is different.
- Frequent or early withdrawals shrink growth fast.
- The chart is a smooth model; real markets zig and zag.
- More frequent compounding can boost growth even if the headline rate stays the same.
Limitations & assumptions
The model assumes one steady annual rate and fixed compounding, but real returns bounce around. It skips taxes, fees, penalties, bid/ask spreads, and changing rates over time. Inflation is one percentage for a simple “real” view and won’t mirror your spending. Deposits and withdrawals are spread evenly on the schedule you pick, and it doesn’t model employer matches or account rules. Use the numbers as a directional guide, not a forecast or advice.
FAQs
Quick answers
What does this tool estimate?
It projects a future balance using your rate, compounding frequency, timeline, and any scheduled deposits or withdrawals, with an optional inflation-adjusted view.
What’s included or excluded?
Included: principal, rate, frequency, recurring cash flows, and a simple inflation factor. Excluded: taxes, fees, penalties, market volatility, and account-specific rules.
What assumptions are baked in?
A constant annual rate, even cash flow timing, and fixed compounding throughout your chosen horizon. Inflation is treated as one percentage, not a detailed CPI basket.
Can I save scenarios or export results?
Yes. Save scenarios for comparison, export tables to CSV, and download a PDF snapshot after running a calculation.
Is my data private?
Calculations run in your browser; inputs are not shared unless you export files locally. Clear the form or refresh to remove your entries.
Is this financial advice?
No. This is an educational model, not personal advice. Speak with a qualified professional before making financial decisions.
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