Growth calculator
Compound growth, with every assumption visible.
Model a starting balance and recurring contributions with explicit compounding, contribution timing, and purchasing-power assumptions.
Assumptions used
Every assumption is adjustable and bounded. The summary below repeats the complete current model, including frequency and timing conventions.
Money in the account before the first contribution interval begins.
Allowed range: 0 to 100000000.
Amount added once per selected contribution interval.
Allowed range: 0 to 1000000.
Contribution frequency
Choose whether that contribution amount is deposited every month or every year.
The stated annual return before the effect of compounding within the year.
Allowed range: -99 to 50 %.
Choose how many complete years to model.
Compounding frequency
How often the nominal annual rate is divided and applied.
Contribution timing
Beginning contributions receive one additional interval of modeled growth.
Used only for the today's-dollar result. Enter 0% to turn off the adjustment.
Allowed range: -20 to 30 %.
- Initial principal
- $10,000
- Recurring contribution
- $500 each month
- Contribution timing
- End of each month
- Nominal annual rate
- 7.0%
- Compounding
- Monthly (12 times per year)
- Projection horizon
- 30 years
- Annual inflation
- 2.5%
- Effective annual return
- 7.229%
Positive result
Ending nominal value
$691,150
The modeled balance in future dollars before adjusting for purchasing power.
Caution
Inflation-adjusted value
$329,501
Estimated purchasing power after 2.5% annual inflation; not a forecast.
Positive result
Total contributed
$190,000
$10,000 initial principal + $180,000 recurring contributions.
Positive result
Interest earned
$501,150
Ending nominal value minus initial principal and recurring contributions.
Current cash-flow conventionEnd of each month: the model applies growth, then adds the contribution for every month.
What builds the ending balance
The stacked visual and table use the same annual values. Patterns, labels, and the semantic table preserve the meaning without relying on color alone.
| Projection year | Initial principal | Cumulative contributions | Interest earned | Ending value |
|---|---|---|---|---|
| Start | $10,000 | $0 | $0 | $10,000 |
| Year 1 | $10,000 | $6,000 | $919 | $16,919 |
| Year 2 | $10,000 | $12,000 | $2,339 | $24,339 |
| Year 3 | $10,000 | $18,000 | $4,294 | $32,294 |
| Year 4 | $10,000 | $24,000 | $6,825 | $40,825 |
| Year 5 | $10,000 | $30,000 | $9,973 | $49,973 |
| Year 6 | $10,000 | $36,000 | $13,782 | $59,782 |
| Year 7 | $10,000 | $42,000 | $18,299 | $70,299 |
| Year 8 | $10,000 | $48,000 | $23,578 | $81,578 |
| Year 9 | $10,000 | $54,000 | $29,671 | $93,671 |
| Year 10 | $10,000 | $60,000 | $36,639 | $106,639 |
| Year 11 | $10,000 | $66,000 | $44,544 | $120,544 |
| Year 12 | $10,000 | $72,000 | $53,455 | $135,455 |
| Year 13 | $10,000 | $78,000 | $63,443 | $151,443 |
| Year 14 | $10,000 | $84,000 | $74,587 | $168,587 |
| Year 15 | $10,000 | $90,000 | $86,971 | $186,971 |
| Year 16 | $10,000 | $96,000 | $100,683 | $206,683 |
| Year 17 | $10,000 | $102,000 | $115,820 | $227,820 |
| Year 18 | $10,000 | $108,000 | $132,486 | $250,486 |
| Year 19 | $10,000 | $114,000 | $150,790 | $274,790 |
| Year 20 | $10,000 | $120,000 | $170,851 | $300,851 |
| Year 21 | $10,000 | $126,000 | $192,796 | $328,796 |
| Year 22 | $10,000 | $132,000 | $216,760 | $358,760 |
| Year 23 | $10,000 | $138,000 | $242,892 | $390,892 |
| Year 24 | $10,000 | $144,000 | $271,345 | $425,345 |
| Year 25 | $10,000 | $150,000 | $302,290 | $462,290 |
| Year 26 | $10,000 | $156,000 | $335,905 | $501,905 |
| Year 27 | $10,000 | $162,000 | $372,384 | $544,384 |
| Year 28 | $10,000 | $168,000 | $411,934 | $589,934 |
| Year 29 | $10,000 | $174,000 | $454,777 | $638,777 |
| Year 30 | $10,000 | $180,000 | $501,150 | $691,150 |
Formula and interpretation notes
Contribution-interval rate = (1 + r/m)^(m/k) − 1, where r is the nominal annual rate, m is compound periods per year, and k is contributions per year. This is the standard periodic compounding structure described by the Investor.gov compound interest resource.
Real ending value = nominal ending value ÷ (1 + inflation)^years. Calculations keep full precision and round only the numbers shown on screen.
Nominal dollars are the future balance produced by the entered return and contribution assumptions. Today's dollars discount that balance by the entered inflation rate to estimate purchasing power. Neither amount predicts a market return or future inflation.
A beginning contribution is deposited before interval growth and therefore receives one more interval of modeled growth than the same end contribution. The setting applies consistently to every monthly or annual contribution in the projection.
Educational illustration only. Constant returns and inflation are simplifying assumptions, not forecasts, guarantees, or individualized investment recommendations.
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Questions this model answers
What does a nominal annual rate mean?
It is the stated annual rate before the effect of compounding within the year. This calculator divides that rate by the selected number of compound periods, then compounds each period without rounding.
Why does contribution timing change the result?
A beginning-of-period contribution receives one additional contribution interval of modeled growth compared with an otherwise identical end-of-period contribution.
What is the inflation-adjusted result?
It discounts the ending nominal value by the selected annual inflation rate to express estimated purchasing power in today's dollars. It is not a forecast of future prices or returns.
Is this a forecast or investment advice?
No. It is an educational, deterministic illustration that holds every entered assumption constant. Actual returns, inflation, taxes, fees, and cash flows will differ.