Definition
Bankroll management is the discipline of deciding how much to stake from a set betting fund so losses from normal variance do not wipe out the account. The core formula is:
stake = bankroll × stake percentage
For Kelly staking, the formula is:
Kelly fraction = (bp - q) / b
where b is net decimal odds, p is your estimated win probability, and q = 1 - p.
Worked Example
A bettor has a $2,000 bankroll and uses a 1% flat-stake rule.
$2,000 × 0.01 = $20
Each bet is $20, regardless of confidence.
For a Kelly example, take a -110 line. Decimal odds are 1.9091, so b = 0.9091. If the bettor prices the bet at 55% win probability:
(0.9091 × 0.55 - 0.45) / 0.9091 = 0.055
Full Kelly stake is 5.5% of bankroll:
$2,000 × 0.055 = $110
Half Kelly would stake $55.
Why It Matters
Bankroll management helps a bettor keep bet size tied to account size and edge size. It is most useful when a bettor has many wagers ahead and needs losses, wins, and stake sizing to remain auditable.