Proportional Staking & the Risk of Ruin

## What Proportional Staking Is Proportional staking means betting a fixed percentage of your current bankroll on every bet. As your bankroll grows, your stakes grow. As it shrinks, your stakes shrink. Example: 2% proportional staking. Bankroll starts at £1,000 → stake = £20. After winning £200 → bankroll = £1,200 → next stake = £24. ## The Mathematical Advantage Proportional staking has a key theoretical property: you cannot go bust. If you always stake a percentage of what remains, you will always have something left. The sequence of bets affects the terminal bankroll, but not the existence of one. Compare: flat staking with a large enough downswing can take you to zero if stakes are too high relative to bankroll. ## The Growth Rate With positive expected value and proportional staking, the bankroll grows exponentially. The same 5% ROI that produces linear growth under flat staking produces compound growth under proportional staking — though the absolute numbers only diverge meaningfully over very long runs. ## Risk of Ruin Under Flat Staking Risk of ruin is the probability that your bankroll hits zero before it reaches a target. Under flat staking at too-high stake sizes, this is non-trivial. Rule of thumb: your maximum stake per bet under flat staking should be no more than 1–3% of your bankroll. At 3% stakes, a losing run of 34 consecutive bets wipes you out. At 1% stakes, you need a run of over 100 losses in a row — vanishingly unlikely even in a bad strategy.