The Kelly Criterion: How Much Should You Actually Bet?

You can pick winners and still go broke if you bet too much on the wrong spots. Bet sizing — not just picking — is what protects and compounds a bankroll. The standard answer is the Kelly Criterion.

What the Kelly Criterion does

Kelly gives you the mathematically optimal fraction of your bankroll to bet, based on your edge and the odds. Bigger edge → bigger bet. Smaller edge → smaller bet. It maximizes long-term growth while mathematically guaranteeing you never bet your whole roll.

Why most pros use "fractional" Kelly

Full Kelly is aggressive and assumes your edge estimate is exactly right — which it never is. Most professionals bet a fraction (often quarter- or half-Kelly) to smooth out variance and survive inevitable cold streaks. You give up a little theoretical growth for a lot more stability.

The practical version

• →Define 1 unit as a small, fixed percent of your bankroll (1–2%).
• →Size bets up or down from there based on edge — not gut feel.
• →Never chase losses by increasing stake; let the math do the sizing.

Closeline attaches a fractional-Kelly stake to every pick, so you know not just what to bet but how much — sized to the edge, not your emotions.