Kelly Criterion Bet-Sizing Practice
A coin tilted in your favour, round after round — size your bets against ruin.
Free account required to play; this simulator is a Premium feature.
Having an edge isn't enough — you have to size your bets to it. Kelly Betting gives you a coin tilted in your favour and asks how much to stake each round. Bet too little and your capital barely grows; bet too much and a bad run wipes you out. The game scores you against the Kelly-optimal path.
It builds the sizing discipline that separates good traders from lucky ones: turning an edge into compounding growth while respecting variance and the risk of ruin — a favourite topic in trading interviews.
What it's modelled on
Bet-sizing and Kelly-criterion interview questions
This drills a recurring trading-interview theme rather than a single named test: the position-sizing questions used to see whether you can turn an edge into growth without risking ruin — the Kelly-criterion reasoning that follows once you've shown you can spot a good bet.
What it trains
- Bet and position sizing given an edge
- The Kelly criterion and log-growth intuition
- Managing variance and the risk of ruin over many rounds
How it's scored
Each round you choose a stake on a favourable bet; your final bankroll is compared to the Kelly-optimal trajectory. A Premium game with configurable rounds.
Related guides
Frequently asked questions
- What is the Kelly criterion and why do interviews ask about it?
- The Kelly criterion is the bet size that maximises long-run log growth of your capital given an edge. Interviews use it because sizing is where edge turns into (or loses) money — it tests whether you understand growth versus ruin, not just expected value.