Finance Simulation Calculator
| Start Amount ($) | Annual Investment ($) | Annual Rate (%) | Profit | Total |
|---|---|---|---|---|
| 30,999.76 | 60,999.76 |
Editable Simulation Per Year
| Year | Start Amount | Contribution | Rate % | Profit | Accumulated Profit | Total |
|---|---|---|---|---|---|---|
| 1 | 10,000.00 | 1,200.00 | 1,200.00 | 13,200.00 | ||
| 2 | 13,200.00 | 1,520.00 | 2,720.00 | 16,720.00 | ||
| 3 | 16,720.00 | 1,872.00 | 4,592.00 | 20,592.00 | ||
| 4 | 20,592.00 | 2,259.20 | 6,851.20 | 24,851.20 | ||
| 5 | 24,851.20 | 2,685.12 | 9,536.32 | 29,536.32 | ||
| 6 | 29,536.32 | 3,153.63 | 12,689.95 | 34,689.95 | ||
| 7 | 34,689.95 | 3,669.00 | 16,358.95 | 40,358.95 | ||
| 8 | 40,358.95 | 4,235.89 | 20,594.84 | 46,594.84 | ||
| 9 | 46,594.84 | 4,859.48 | 25,454.33 | 53,454.33 | ||
| 10 | 53,454.33 | 5,545.43 | 30,999.76 | 60,999.76 |
Why Use a Year-by-Year Simulation
The compound interest calculator assumes one fixed rate for the whole period, which is easy to reason about but unrealistic — real portfolios don't grow the same percentage every single year. This simulator lets you set a different rate and contribution for each individual year (or month), so you can model things like a market downturn early in retirement, a few strong growth years followed by a correction, or a gradually increasing contribution as your income grows.
This is especially useful for testing sequence-of-returns risk — the idea that the order returns happen in, not just their average, matters a lot when you're also withdrawing or contributing money. Two portfolios with the same average annual return can end up wildly different in value if one hits its worst years early and the other hits them late.
Frequently Asked Questions
What's the difference between this and the compound interest calculator?
The compound interest calculator applies a single rate uniformly across the whole timeline. This simulator lets every year (or month) have its own rate and contribution amount, which is closer to how real markets and real savings behavior actually work.
What is sequence-of-returns risk?
It's the risk that the timing of gains and losses — not just their average — affects your final outcome, especially when contributions or withdrawals are happening alongside growth. A crash early in accumulation hurts less than the same crash early in retirement withdrawals, because there's more time to recover.
Can I model a market crash or recession scenario?
Yes — set one or more years to a negative rate to see how a downturn at a specific point in your timeline affects the final balance, then compare that against the same downturn placed at a different point in the sequence.
Does this support both annual and monthly modeling?
Yes, switch between Year and Month mode above the table. Monthly mode is useful for shorter, more granular scenarios, while yearly mode is better for modeling decades-long retirement or growth simulations.