Value notes
How big a bankroll do you need for value betting
The bankroll is the denominator in every Kelly stake. Work backward from the stake size you want, and let losing streaks set the floor.
The Kelly formula tells you what fraction of your bankroll to stake, which makes the bankroll itself the unanswered half of the setup. The size is not a preference; it falls out of two numbers: the stake you want to place and the fraction you are willing to bet. Work backward from those, and the bankroll sets itself.
The bankroll is a tool, not a savings account
The bankroll is the money your staking math divides into. It has to be money whose complete loss would change nothing about your life, because the whole point of the exercise is a balance that can swing. Keep it separate: a bankroll that shares an account with rent money will be spent as rent money, and the record of your results will be contaminated by withdrawals.
Work backward from the stake
The Kelly staking guide works the example: with a fair chance of 46.13% and a price of 2.25, full Kelly is 3.04% of the bankroll, and the quarter Kelly it recommends as a starting fraction is 0.76%, or 7.61 on a bankroll of 1,000, checked 2026-10-04.
Flip that around. If the smallest stake you care to place is 10, a quarter-Kelly bankroll needs to be about 1,300, because 10 is 0.76% of it. If you want 25 on the same edge profile, you need about 3,300. The formula is one division: the bankroll equals the stake you want divided by the fraction you will actually bet, and your typical edge size sets how large that fraction tends to be. The EV calculator shows the stake figure for any prices you feed it, so you can see your own fraction before committing to a number.
Let losing streaks set the floor
Value betting loses most of its bets at prices above even money, and long losing runs are normal over hundreds of bets. The fraction is what keeps you in the game through them. Ten straight losses at quarter Kelly on the numbers above cost about 7% of the roll, because each stake shrinks as the balance falls: 0.9924 multiplied by itself ten times is about 0.926.
The same run at full Kelly leaves about 73% of the roll. Both survive, but the second survives with a curve most people cannot sit through, which is why the guide calls the fraction a temperament decision as much as a mathematical one.
Recompute as it moves
The bankroll figure is not a number you set once. The guide's own answer on timing: update it before every stake, from the current balance, because Kelly is a fraction of what you hold now. A weekly ritual defeats the point; the division is cheap enough to do per bet.
Bankroll from the stake you want, floor from the losing streak you should expect, balance refreshed per bet. Then the formula does the rest.