Compounding Calculator
Realistic growth curves — with the costs and variance left in. Compounding is real. The screenshots on Instagram usually are not.
Your assumptions
The formula — and its honest asterisk
The screenshots on Instagram use this formula with a fantasy r and no c. Costs compound against you every single period, and because real returns vary, the geometric growth you actually realize runs below the arithmetic average you plug in. Both corrections are quiet, relentless, and missing from every get-rich chart you've ever been shown.
Frequently asked questions
Why does my real growth lag this curve?
Variance drag. The formula compounds your average return, but real period returns vary around that average — and volatility itself costs growth (roughly σ²/2 per period). A +10%/−10% pair of months does not break even; it loses 1%.
How much do costs really matter?
They compound exactly like returns do, every period, forever. A 0.3% per-period cost against a 2% edge consumes 15% of the growth rate — drag the cost slider and watch the final balance move to see it.
What is a realistic per-period return?
Far lower than social media suggests. Durable strategies measure monthly edges in low single digits — the calculator warns above 5% per period because sustained numbers beyond that almost always mean an inputs problem, not a genius.