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Stake the exact amount your edge is worth

The Kelly Criterion sizes every bet for maximum long-term growth. Enter your bankroll, the odds and your win probability — get the optimal stake instantly, then dial it to half or quarter Kelly to tame variance.

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Recommended stake
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% of bankroll
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Full Kelly %
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Your edge
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Kelly fraction = (b·p − q) ÷ b, where b = decimal odds − 1. A negative result means no edge — don't bet.

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We size every pick with Kelly for you

Each model pick already carries its calibrated probability and a suggested stake — no maths required. See tonight's sized plays, free.

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How to use it

  1. Enter the bankroll you're betting with.
  2. Set your honest win probability — your real edge, not hope.
  3. Add the odds in decimal, American or fractional.
  4. Choose half or quarter Kelly to soften the swings.

Worked example

Bankroll$1,000
Win prob55%
Odds2.00
Full Kelly10.0%
Half-Kelly stake$50.00

Kelly — quick answers

What is the Kelly Criterion?

A formula that sizes bets to maximise long-term bankroll growth: fraction = (b·p − q) ÷ b.

Full, half or quarter Kelly?

Most pros use half or quarter Kelly — far less volatile and far more forgiving if your probability estimate is slightly off.

What happens if I have no edge?

If the formula returns zero or negative, the price doesn't beat your probability. The optimal stake is nothing — don't bet.

Bet Better is not a bookmaker and does not accept wagers. Tools are for information only. Gamble responsibly — never stake more than you can afford to lose.

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