Blackjack bankroll calculator

Expected result is hands × average bet × edge. At a 1% edge, $50 average over 2,000 hands, that is $1,000. It is the center of a wide spread, not a promise.

Typical range is one standard deviation each way. About two sessions in three land inside it. Blackjack swings about 1.15 betting units per hand, which is why the range looks brutal next to the expectation.

Risk of ruin is the chance this bankroll goes to zero before the edge can work: e raised to (−2 × edge × bankroll ÷ variance). Small bankrolls and big bets push it toward 100% fast.

N0 is the number of hands where your expected win equals one standard deviation. Below N0, luck dominates. Above it, skill starts to show.

Estimates, not guarantees. They assume flat average bets, a constant edge, and no table limits or backoffs cutting your session short.

Take a counter with a $10,000 bankroll spreading $25 to $200 for an average bet of $50, playing 20 hours at 100 hands an hour with a 1% edge. That is the calculator's default, and here is what each output is telling you.

2,000 hands, $100,000 in total action. Twenty hours of play puts one hundred thousand dollars at risk across all those hands. Every percentage point of edge is worth $1,000 of expectation on that action.

Expected result: +$1,000. That is $50 an hour before expenses. It sounds modest because it is: a 1% edge is a grind, not a jackpot.

Typical range: −$1,571 to +$3,571. Two times in three, twenty hours ends somewhere in that band. Notice that losing $1,500 over a weekend is completely normal for a winning player. If that sentence bothers you, the bankroll is too small or the bets are too big.

Risk of ruin: about 5%. One time in twenty, this bankroll goes to zero. Most counters consider that the upper limit of acceptable; professionals usually size for 1 to 2%.

N0: about 13,200 hands. That is 130+ hours, or months of weekend play, before the edge reliably shows through the luck. Anyone judging their counting by one weekend's results is reading noise.

The lesson most people miss: the bankroll requirement comes from the variance, not the edge. Doubling your edge from 0.5% to 1% doubles the expectation, but the swings barely shrink. There is no edge big enough to make a small bankroll safe.

Work backward from risk of ruin. Pick the largest bet you will make, then size the bankroll so the calculator shows a risk of ruin you can live with, usually under 5%. A common starting point is 100 times your maximum bet, then adjust: aggressive spreads and part-time play need more cushion, not less.

Three rules keep bankrolls alive. Separate it completely from rent money; a bankroll you cannot afford to lose gets played scared, and scared money makes strategy mistakes. Never chase. The math does not know you are down, and pressing bets after losses is how edges evaporate. Recompute after big swings. If the bankroll halves, your bets halve too, or your risk of ruin doubles.

For basic strategy players the calculator answers a different question: what does a casino trip cost? Set the edge to −0.5% and read the expected result as the price of entertainment. A $25 average bet over four hours costs about $50 in expectation, with swings of a few hundred either way. That is a fair price for a night out, as long as you know it going in.