Calculators
How much to stake—
Give a bankroll, a probability and a price and this becomes the stake the edge supports.
Where you’re buying
↑ Break-even 52.4%Edge +2.6 pts ↑
Kelly fraction
0.25×QUARTER
Full Kelly$55.005.50% of the roll
Edge+2.6 ptsbreak-even 52.4%
Growth / bet+0.06%expected log growth
To win$12.50profit if it lands
Expected log growth by fractionPast 1.00× you add variance and subtract growth
Full Kelly assumes your probability is exact — it never is. Fractional Kelly trades a little growth for a lot less ruin, which is why ¼–½ is the standard.
Show the math
f* = (b·p − q) / b, b = decimal − 1b = 0.9091, p = 0.5500 → f* = 5.50%
stake = bankroll × f* × 0.25$1,000.00 × … = $13.75