Compound Interest Calculator
Forecast the long-term future value of your initial investment and monthly recurring contributions across various compounding frequencies and assumed return rates.
Investment Parameters
Customize your principal, recurring deposits, and growth assumptions
Starting lump-sum principal amount.
Regular recurring deposit made at the end of each month.
Change this assumption to see how the projected value changes.
Frequency interest is credited.
Total investment timeframe in years.
Compound Growth Summary
Projected future portfolio value & growth composition
Contribution vs. Growth Breakdown
* Projections reflect theoretical mathematical growth based on user-supplied parameters. Actual market returns fluctuate and are not guaranteed.
What If You Adjust Your Strategy?
Compare your current baseline projection against alternative contributions, rates, and time horizons.
What If?
Change an input to see how the result changes.
Accumulation Schedule
Year-by-year and month-by-month breakdown of principal contributions and compound growth
| Year | Starting Balance | Annual Deposits | Estimated Growth | Ending Balance | Cumulative Principal | Cumulative Growth |
|---|---|---|---|---|---|---|
| Year 1 | $10,000.00 | +$6,000.00 | +$919.19 | $16,919.19 | $16,000.00 | $919.19 |
| Year 2 | $16,919.19 | +$6,000.00 | +$1,419.38 | $24,338.58 | $22,000.00 | $2,338.58 |
| Year 3 | $24,338.58 | +$6,000.00 | +$1,955.73 | $32,294.31 | $28,000.00 | $4,294.31 |
| Year 4 | $32,294.31 | +$6,000.00 | +$2,530.85 | $40,825.16 | $34,000.00 | $6,825.16 |
| Year 5 | $40,825.16 | +$6,000.00 | +$3,147.55 | $49,972.70 | $40,000.00 | $9,972.70 |
| Year 6 | $49,972.70 | +$6,000.00 | +$3,808.82 | $59,781.53 | $46,000.00 | $13,781.53 |
| Year 7 | $59,781.53 | +$6,000.00 | +$4,517.90 | $70,299.43 | $52,000.00 | $18,299.43 |
| Year 8 | $70,299.43 | +$6,000.00 | +$5,278.24 | $81,577.68 | $58,000.00 | $23,577.68 |
| Year 9 | $81,577.68 | +$6,000.00 | +$6,093.55 | $93,671.22 | $64,000.00 | $29,671.22 |
| Year 10 | $93,671.22 | +$6,000.00 | +$6,967.79 | $106,639.02 | $70,000.00 | $36,639.02 |
How Compound Interest Works
Compound interest represents the exponential multiplication of wealth. When capital is invested, growth earned in each cycle is credited back to the principal balance, generating additional interest in subsequent compounding intervals.
1. Mathematical Compounding Formulas
For an initial lump sum, the future value after t years is governed by the standard compounding equation:
- A = Projected Future Value
- P = Initial Principal Investment
- r = Assumed Annual Interest Rate (as decimal)
- n = Compounding Periods Per Year (Annual=1, Semi-Annual=2, Quarterly=4, Monthly=12, Daily=365)
- t = Investment Duration in Years
2. Monthly Recurring Contribution Convention
FinoQuick models monthly contributions as end-of-month deposits and converts the selected annual compounding convention into an equivalent monthly growth rate for the recurring contribution stream:
Future contributions compound according to the standard ordinary annuity stream formula:Acontributions = C × [ (1 + rmonthly)M - 1 ] ÷ rmonthly, where C is the monthly deposit and M is the total number of months.
3. Total Principal vs. Estimated Growth
The total ending balance is the exact sum of your total principal invested (initial investment plus all recurring contributions) and cumulative estimated mathematical growth.
Important Model Disclosures
- This calculator provides mathematical projections based on the assumptions you enter.
- Actual investment returns can vary significantly and may be positive or negative over any timeframe.
- Projected growth is not guaranteed and does not account for investment fees, taxes, or inflation.
- The calculator is for educational scenario modeling and does not constitute investment advice.
Frequently Asked Questions
Clear answers to common questions about compound interest, compounding frequencies, and return assumptions.
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