Flexible contribution timing
Model weekly through annual deposits at the beginning or end of each contribution period.
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Finance · Savings growth
Compound Interest Calculator
Explore how a starting balance, recurring contributions, time, compounding, and changing rate assumptions shape long-term growth.
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Projected balance after 20 years
$300,851
7.00% nominal rate · 7.229% effective annual yield
Starting balance
$10,000
Added deposits
$120,000
Interest earned
$170,851
Today’s value
$183,600
Target reached during year 18.
Contributions versus estimated growth56.8% from interest
Growth timeline
Balance versus money contributed
Rule of 72
≈ 10.3 years to double
Projected balanceMoney contributed
Scale to $300,851Lower-rate case5.00%
$232,643
Base projection7.00%
$300,851
Higher-rate case9.00%
$394,035
Year-by-year projection
Contributions and compound growth
| Year | Starting | Added | Interest | Ending balance |
|---|---|---|---|---|
| 1 | $10,000 | $6,000 | $919 | $16,919 |
| 2 | $16,919 | $6,000 | $1,419 | $24,339 |
| 3 | $24,339 | $6,000 | $1,956 | $32,294 |
| 4 | $32,294 | $6,000 | $2,531 | $40,825 |
| 5 | $40,825 | $6,000 | $3,148 | $49,973 |
| 6 | $49,973 | $6,000 | $3,809 | $59,782 |
| 7 | $59,782 | $6,000 | $4,518 | $70,299 |
| 8 | $70,299 | $6,000 | $5,278 | $81,578 |
| 9 | $81,578 | $6,000 | $6,094 | $93,671 |
| 10 | $93,671 | $6,000 | $6,968 | $106,639 |
Planning estimate only, not a promise of returns or financial advice. Actual rates, contribution dates, fees, taxes, market losses, account rules, and rounding can materially change the outcome. “Today’s value” applies only the inflation assumption entered above.
How it works
Turn a savings habit into a visible timeline.
Adjust every major assumption, compare plausible rate cases, and separate the money contributed from the growth attributed to compounding.
- 01
Enter the money contributed
Add a starting balance, recurring deposit, contribution frequency, and whether each deposit arrives at the beginning or end of its period.
- 02
Set the growth assumptions
Choose an annual rate, duration, compounding frequency, inflation rate, scenario variance, and optional savings target.
- 03
Inspect the projection
Compare contributions with interest, review lower and higher rate cases, and follow every projected year in the schedule.
More than a future-value formula
A complete, inspectable growth projection.
Rate and inflation scenarios
Compare lower, base, and higher returns while translating the final balance into inflation-adjusted purchasing power.
Transparent growth schedule
See starting balance, deposits, interest, and ending balance for every year instead of relying on one unexplained total.
Compound-interest questions
Contributions, compounding, inflation, and uncertainty.
What is compound interest?+
Compound interest is interest earned on the original principal and on interest accumulated in earlier periods. This differs from simple interest, which is calculated only on principal.
How are recurring contributions handled?+
The calculator applies each contribution at either the beginning or end of the selected contribution period, then follows the equivalent growth produced by the selected nominal rate and compounding frequency.
Why does compounding frequency matter?+
At the same stated nominal annual rate, more frequent compounding usually creates a slightly higher effective annual yield because earned interest begins earning interest sooner.
What does inflation-adjusted value mean?+
It estimates the future balance in today's purchasing-power terms using your constant annual inflation assumption. It is not an inflation forecast.
Are the lower and higher scenarios forecasts?+
No. They simply repeat the same calculation at the entered rate minus and plus your chosen variance. They illustrate sensitivity and do not predict returns.
Does the result include fees or taxes?+
No. Investment fees, account charges, taxes, contribution limits, employer matches, and withdrawal rules are not automatically included.
Is a compound-interest projection guaranteed?+
No. Savings rates can change and investment returns can be volatile or negative. The output is a mathematical planning estimate, not financial advice or a promise of performance.
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