Investment Calculator
Calculate how an initial investment grows with fixed monthly contributions and a compound annual return, including total money invested and total compound growth earned.
Calculator Inputs
Sets the currency this calculator's numbers are denominated in. This is presentation only — it does NOT convert your numbers between currencies, it only changes how they're formatted.
The lump sum you're starting with.
How much you add at the end of every month (an "ordinary annuity" — the same end-of-period convention Compound Interest Calculator uses). A deposit made this month doesn't start earning a return until next month. Enter 0 for no recurring contributions.
The nominal annual rate of return you expect (e.g. 7 for 7%). Not an effective/APY rate.
How many years (and optionally months) you'll keep investing and growing this balance.
Additional months (0-11). For 18 months, enter 1 year 6 months.
- Final Balance
- $144,572.72
- Total Contributions
- $58,000.00
- Total Compound Growth
- $86,572.72
Year-by-Year Growth Schedule
Balance at the end of each year, from year 0 to year 20.
| Year | Contributions | Growth | Balance |
|---|---|---|---|
| 0 | $10,000.00 | $0.00 | $10,000.00 |
| 1 | $12,400.00 | $801.42 | $13,201.42 |
| 2 | $14,800.00 | $1,834.27 | $16,634.27 |
| 3 | $17,200.00 | $3,115.28 | $20,315.28 |
| 4 | $19,600.00 | $4,662.39 | $24,262.39 |
| 5 | $22,000.00 | $6,494.83 | $28,494.83 |
| 6 | $24,400.00 | $8,633.24 | $33,033.24 |
| 7 | $26,800.00 | $11,099.74 | $37,899.74 |
| 8 | $29,200.00 | $13,918.03 | $43,118.03 |
| 9 | $31,600.00 | $17,113.55 | $48,713.55 |
| 10 | $34,000.00 | $20,713.58 | $54,713.58 |
| 11 | $36,400.00 | $24,747.34 | $61,147.34 |
| 12 | $38,800.00 | $29,246.20 | $68,046.20 |
| 13 | $41,200.00 | $34,243.79 | $75,443.79 |
| 14 | $43,600.00 | $39,776.14 | $83,376.14 |
| 15 | $46,000.00 | $45,881.93 | $91,881.93 |
| 16 | $48,400.00 | $52,602.60 | $101,002.60 |
| 17 | $50,800.00 | $59,982.60 | $110,782.60 |
| 18 | $53,200.00 | $68,069.60 | $121,269.60 |
| 19 | $55,600.00 | $76,914.70 | $132,514.70 |
| 20 | $58,000.00 | $86,572.72 | $144,572.72 |
Contributions vs. Growth
How much of your balance is money you put in (initial investment plus monthly contributions) versus compound growth earned on top of it, at the end of each year.
- Contributions
- Growth
About these results
CalcSpectrum calculators produce automated estimates using established formulas and the specific values you enter. Because real-world outcomes depend on input accuracy, mathematical assumptions, and rounding conventions, please verify critical figures with an appropriately qualified financial, tax, medical, legal, or other professional, as relevant.
Financial Notice: These figures are informational estimates for personal planning only. They do not constitute financial, investment, tax, or legal advice, nor do they represent a lending offer or credit approval. Provider and financial institution figures, rates, fees, and underwriting requirements may differ.
How It's Calculated
Formula
This calculator projects how an initial investment grows when you add a fixed amount every month and it earns a compounding annual return. Unlike Compound Interest Calculator, which lets you choose annual or monthly compounding, Investment Calculator always compounds and contributes monthly — the schedule most people actually invest on, since it lines up with a monthly paycheck. Each monthly contribution is applied at the end of that month (an "ordinary annuity"), so a contribution made in the current month doesn't start earning a return until the next one. Enter your starting balance, monthly contribution, expected annual return, and how many years you'll keep investing, and the calculator returns your final balance, how much of that is money you actually put in, and how much is compound growth earned on top of it.
Worked Examples
Initial balance plus monthly contributions: $10,000 initial, $200/month, 7% annual return, 20 years
- Periodic rate r/n = 0.07 / 12 ≈ 0.0058333
- Total periods n·t = 12 × 20 = 240
- Final balance = 10000 × (1 + 0.07/12)^240 + 200 × [((1 + 0.07/12)^240 − 1) / (0.07/12)] ≈ $144,572.72
- Total contributions = $10,000 + ($200 × 12 × 20) = $58,000.00; total compound growth ≈ $86,572.72
Recurring contributions only, no starting balance: $0 initial, $300/month, 8% annual return, 15 years
- Periodic rate r/n = 0.08 / 12 ≈ 0.0066667
- Total periods n·t = 12 × 15 = 180
- With $0 principal, only the contribution (annuity) term applies: Final balance = 300 × [((1 + 0.08/12)^180 − 1) / (0.08/12)] ≈ $103,811.47
- Total contributions = $0 + ($300 × 12 × 15) = $54,000.00; total compound growth ≈ $49,811.47
Frequently Asked Questions
Why is total compound growth not just balance minus what I typed in?
It is exactly that: total compound growth equals the final balance minus total contributions, where total contributions is your initial investment plus every monthly contribution you made. It isolates the growth compounding itself produced, separate from the money you actually put in.
Can I model an investment with no recurring contributions?
Yes — set Monthly Contribution to 0. The calculator then computes pure compound growth on your initial investment alone, with no contribution term.
Why does this calculator only offer monthly contributions, not annual?
Investment Calculator is intentionally the simpler, opinionated tool: contributions and compounding are always monthly, matching how most people actually invest — a recurring amount set aside from each paycheck. If you want to compare annual versus monthly compounding directly, use Compound Interest Calculator, which exposes that choice.
When do my monthly contributions start earning a return?
Each monthly contribution is credited at the end of that month, not the beginning. A contribution made during the current month doesn't earn a return until the next month begins. This convention (an "ordinary annuity") is the standard default used in most investment and savings calculators.
Should I enter my expected nominal return or an already-compounded (effective) rate?
Enter the nominal annual rate — the stated rate before any compounding effect is factored in (e.g. "7" for 7%). This calculator derives the actual monthly rate itself, so entering an already-compounded effective/APY rate would double-count the compounding effect.