Most traders think about being right. Surviving is about the other half — how much you put on, and what a rough patch does to you. Five quick, honest calculators. Nothing here is advice; it's arithmetic you can lean on.
Work backwards from what you're willing to lose.
Even a real edge can sink you if you bet too big.
The hole is deeper than it looks — climbing out takes more than falling in.
What one trade is worth, on average — win rate is only half the story.
The bet size for fastest growth — and why almost nobody uses all of it.
Honest notes: these are teaching tools on simplified, two-outcome trades (a typical win, a typical loss), so treat the numbers as well-lit estimates, not guarantees. Risk of ruin is simulated over ~200 trades at fixed-fractional sizing; real life has fees, gaps and streaks these don't fully capture. Not financial advice — arithmetic to think with.