Tools
Investment Growth Calculator
Explore the arithmetic of a fixed annual return compounded monthly. This is an educational scenario—not a forecast of investment performance or spendable income.
Your inputs
Enter a hypothetical fixed-return scenario. Actual returns are variable.
Portfolio value after 5 years
$15,303
$77/mo return equivalent at the entered rate
| Year | Balance | Contributions | Earnings | Monthly return equivalent |
|---|---|---|---|---|
| Year 1 | $3,529 | $3,400 | +$129 | $18 |
| Year 2 | $6,214 | $5,800 | +$414 | $31 |
| Year 3 | $9,064 | $8,200 | +$864 | $45 |
| Year 4 | $12,090 | $10,600 | +$1,490 | $60 |
| Year 5 | $15,303 | $13,000 | +$2,303 | $77 |
Transparent calculation
Formula, example, sources, and limits
This tool is a planning aid. Its output is the arithmetic implied by your inputs, not a forecast, quote, tax calculation, or professional recommendation.
Formula used
next-month balance = current balance × (1 + annual rate ÷ 12) + monthly contribution
Worked example: Starting with $1,000, adding $200 at the end of each month, and entering a constant 6% annual return for five years produces a modeled balance of about $15,303. The displayed $77 monthly figure is only the entered annual rate divided by 12 and applied to that balance.
Assumptions you control
- The entered annual return stays constant and compounds monthly.
- Each contribution is added at the end of the month after that month's modeled return.
- The monthly return equivalent applies the same entered rate to the ending balance; it is not a promised distribution.
Important limitations
- Real investments fluctuate and can lose value; this model contains no volatility or adverse years.
- Fees, taxes, inflation, sequence-of-returns risk, contribution timing, and withdrawal rules are excluded.
- Do not use the result as an expected return, retirement plan, or investment recommendation.
Sources and further reading
- U.S. SEC Investor.gov — Compound Interest Calculator
Primary investor-education reference for initial investment, monthly contribution, time, rate, and compounding inputs.
- MOYUXB — Scoring rubric
Explains why a simplified projection is never treated as evidence that an income stream is low-risk or easy to start.