What Is a Betting Bankroll

A betting bankroll is money you've set aside to bet with and for nothing else, sized so that losing all of it wouldn't touch your rent, your bills or your savings. You run into the word as soon as you read any staking advice, because every rule in that advice is a percentage of this one number. A unit is 1% of bankroll. A Kelly stake is 5.5% of bankroll. No single bet should go above 5% of bankroll. If the number underneath is wrong, every percentage built on top of it is wrong too, and that's why it deserves more thought than most prop bettors give it.

A real bankroll has three properties, and it needs all of them.

First, it's separate. It isn't your checking account, and it isn't whatever happens to be left over this week. It's a fixed amount you've labeled as betting money.

Second, it comes from disposable income only. The responsible-gaming guidance published on the PGA Tour's site by Birches Health puts the test in plain terms: the bankroll "needs to be an amount that you can afford to lose completely." The same piece says never to borrow or use credit to fund it.

Third, it covers a period of time. That guidance recommends budgeting over months or a year, not a single day or weekend. For a props bettor, that means one bankroll for the NBA season, not a fresh one every Sunday.

The "afford to lose completely" test isn't just caution. Even a bettor with a real edge can spend a long time behind. In a Wizard of Odds worked example, someone who wins 55% of $100 bets at -110 expects to be up $500 after 100 bets, yet still has roughly a 30% chance of being behind at that point. If losing that money would hurt you, you'll quit or chase before the edge has time to show up.

The best case against all this is that money is fungible. A dollar in your sportsbook account spends the same as a dollar in checking, so a separate pot is just bookkeeping. That's true about the money. But the separation is there for the decision, not the dollars. Once the number is fixed, a bad week becomes a percentage of a known total rather than a vague feeling that you should win it back. And most bettors don't do it. The American Gaming Association's 2025 survey found 60% of sports bettors "always" or "usually" set a budget before gambling. That leaves four in ten who don't.

Unit size. OddsShopper defines a unit as a fixed percentage of bankroll, typically 1%, so a $1,000 bankroll gives you a $10 unit. Its author, Jake Hari, puts it this way: "A unit is a percentage, not a fixed dollar." TheSpread.com gives a range of 0.5% to 2%, with $25 as the 1% unit on a $2,500 bankroll. Either way, your unit means nothing until the bankroll is defined.

Kelly stakes. The Kelly formula gives its answer as a fraction of bankroll. In Wizard of Odds' example, a -110 bet you win 55% of the time comes out at 5.5%, about $55 on $1,000. Use a careless bankroll figure, such as your total savings, and the formula will happily tell you to stake far more than you should.

Resizing. Because units are percentages, they change when the bankroll does. TheSpread.com suggests recalculating once the bankroll has moved by about 25% to 33%, or checking monthly. That only works if you know the starting number and have kept track of it.

Two things get mistaken for a bankroll often enough to be worth separating out.

Write the number down before the season starts, and ask yourself one question about it: if this were gone by the playoffs, would anything else in my life change? If the answer is yes, the number is too big, and no staking plan will make up for that.

Then watch for the giveaway. If a cold run has you thinking about topping up the account, you're either chasing or the original number was dishonest. The Birches Health guidance says a conservative unit is what keeps cold streaks from "prompting redeposits," and the Wizard of Odds figures show those streaks come for winning bettors too. Planning for them before they arrive is what surviving a losing streak mostly comes down to.

Once the number is honest, the rest is arithmetic: how big a unit to use, flat stakes or a fraction of Kelly, and how far a normal season can pull you down.