Enter a price, your own win chance and your bankroll to see how much the Kelly formula says to risk — at full, half and quarter stake.
Full Kelly
$83.33
Half Kelly
$41.67
Quarter Kelly
$20.83
Stake of bankroll
8.33%
Your edge
4.55 pts
Value per $1
+10.00%
How Kelly works
Kelly sizes a bet by how big your edge is, not by how confident you feel. The formula is (decimal odds × win chance − 1) ÷ (decimal odds − 1). No edge means no stake.
Full Kelly is the mathematically fastest way to grow a bankroll, but only if your win chance is exactly right. It never is, so most disciplined bettors use a half or quarter of it — the growth is slightly slower and the swings are far smaller.
Kelly is a staking reference, not a prediction. Find the fair price first, then size the bet.