The American Gaming Association expects Americans to legally bet $3.3 billion on this year’s men’s and women’s NCAA tournaments, up from the $3.1 billion it projected for 2025. If some of that is yours this Sweet 16 weekend, you need a sports betting budget, and a real one starts with a number most bettors never look at: 52.38%. That is the share of standard bets you have to win just to come out even. Pick winners at a coin-flip rate and you lose money slowly. Pick them at a coin-flip rate inside a parlay and you lose it a lot faster.
The usual advice is to “set a limit and treat it like entertainment.” That’s fine as far as it goes, but it skips the part that decides how long your entertainment money lasts: which bets you make and whether your limit applies to the cash you put in or to the total you wager. Those two choices change the cost of a weekend of betting by a factor of almost four.
The vig at -110 means your sports betting budget starts in a hole
A standard point-spread bet is priced at -110. You risk $110 to win $100, or $10 to win $9.09. The sportsbook sets both sides of the game at that price, so if it takes $110 on each team, it collects $220 and pays the winner $210. The $10 left over is its cut, called the vig or the juice.
Run that backward and you get the break-even rate. A $10 bet at -110 returns $19.09 when it wins, so you need to win 10 divided by 19.09 of the time, which is 52.38%, to stay flat. Anything below that and the account shrinks. If you’re truly picking games at 50%, which is what a sharply set line is designed to make you do, you lose about 4.5 cents of every dollar you bet. On a single $10 bet that’s 45 cents in expected cost. It sounds trivial, and for one bet it is.
The trouble is that nobody makes one bet during March Madness. The 45 cents is charged again on every wager, including the ones you make with money you just won.
Parlays multiply the house edge with every leg
A parlay strings several bets together and only pays if every one of them hits. The payout looks huge because it is the product of each leg’s payout. That multiplication works on the sportsbook’s margin too.
Take a four-leg parlay where each leg is a -110 coin flip. Priced fairly, four 50/50 events should pay 16 times your stake, because the chance of hitting all four is 1 in 16. Multiplying four -110 payouts together gives you about 13.28 times your stake instead. The gap between 13.28 and 16 is a house edge of roughly 17%, close to four times the 4.5% on a single straight bet. Two legs carry about an 8.9% edge, three legs about 13%, and six legs about 24%. Many books also post flat parlay tables rather than multiplying the legs out, and those are often worse: a six-leg parlay paying +4000 (41 times your stake) against a fair payout of 64 times your stake carries an edge near 36%.
Same-game parlays deserve extra suspicion. The legs in a same-game parlay are correlated (if a star scores 30, his team probably covers), so the book can’t simply multiply the individual odds. It prices the combination itself, and that pricing is opaque to you. You can’t check the math, and the sportsbook has no reason to make it generous. I’d assume any same-game parlay costs you more than the independent-leg numbers above, not less.
What $150 costs depends on how you bet it
Say you set aside $150 for the tournament’s second weekend and plan fifteen $10 bets. The money you put in is identical in each scenario below. What changes is the price you pay for it.
| How you bet the $150 | House edge | Expected cost |
|---|---|---|
| Fifteen $10 straight bets at -110 | 4.5% | $6.82 |
| Fifteen $10 four-leg parlays (-110 legs) | 17.0% | $25.47 |
| $150 recycled until the edge consumes it | 4.5% | $150 after about $3,300 wagered |
The first row is $150 multiplied by the 4.5% edge, which comes to $6.82. That’s the expected price of a weekend of watching games with something riding on them, and for a lot of people that’s a reasonable entertainment expense. The second row is $150 multiplied by the 17% four-leg edge, or $25.47. Each of those parlays pays $132.83 if it lands, but each has only a 6.25% chance, so across fifteen tickets you’d expect less than one winner (0.94, to be exact), and there’s about a 38% chance you hit none at all.
The third row is the one the “set a limit” advice misses. If you take your $150, win a few, and keep betting the proceeds, the edge keeps getting applied to every new wager. Divide $150 by 4.5% and you get $3,300: on average, that is how much total betting it takes for the vig alone to grind the whole budget down. You never have to deposit another cent for the sportsbook to collect the full $150; you just have to keep cycling the same dollars. Your expected cost is set by your total handle, so the limit has to go on the money you deposit, never on the money you wager.
What the research says legal betting does to household finances
Economists Scott Baker, Justin Balthrop, Mark Johnson, Jason Kotter and Kevin Pisciotta tracked transaction data for households in states that legalized online betting, in an NBER working paper issued in November 2024. Their estimate: each $1 of online sports betting reduced net investment by about $0.99, meaning betting money came almost dollar for dollar out of savings and investing rather than out of other fun spending. Net investment fell about 14%. For households with low savings, the drop was about 41%, and their credit card balances rose by about $368, an 8% increase. Overdrafts became more frequent.
A separate study by Brett Hollenbeck of UCLA Anderson, with Poet Larsen and Davide Proserpio, looked at credit records. As summarized by the UCLA Anderson Review in February 2026, the likelihood of a personal bankruptcy filing rose 25% to 30% in states with online sports betting, average debt collection amounts rose 8%, and credit card and auto loan delinquencies each rose around 8%.
Most people in those samples bet small amounts, so the averages hide a lot of harmless $20 weekends. Read the $0.99 figure again, though. It says the typical bettor didn’t trim restaurants or streaming to fund the habit. The money came out of savings, which is what happens to any spending that never gets its own budget line.
How to set a sports betting budget that holds up
Start by giving betting its own category next to streaming and concert tickets, fund it from money left over after savings and bills, and decide the amount before the bracket comes out, not after a bad Thursday. If you already use a spending plan like the one in our guide to building a realistic budget, this is one more row.
Next, budget the expected cost as well as the deposit. Fifteen straight bets on $150 is a roughly $7 night out. Fifteen four-leg parlays is a $25 one. Knowing the price lets you decide whether a long-shot ticket is worth paying nearly four times as much for the same three hours of basketball. Sometimes it might be, but it’s a purchase, and you should know what you’re paying.
Then make the cap mechanical. FanDuel and DraftKings both let you set deposit limits in your account settings, and a deposit limit is precisely the tool that stops the $3,300 churn problem, because once the $150 is in, nothing more goes in until next month. Pair it with a rule that winnings above a set amount get withdrawn instead of rebet. A separate checking account or a prepaid card for betting deposits also keeps the activity out of your main spending, which makes it easy to see at the end of the month. Review the number alongside the rest of your categories, the same way you would in a regular budget check-in.
Finally, watch for the signs that the line has stopped being entertainment: raising the limit to win back losses, betting with money earmarked for bills, or hiding the account from a partner. If any of that sounds familiar, 1-800-GAMBLER is a free, confidential helpline, and calling it costs less than one parlay.
The cheapest bet is the one priced at 4.5%, not 17%
March Madness is built to make you want action on every game, and the sportsbooks are built to make parlays look like the fun option. The math says otherwise. The real cost of your sports betting budget is the edge you pay on every dollar that moves through the account, and that edge runs from about 4.5% on a straight bet to well over 17% on a four-leg parlay. Cap your deposits, take your winnings out, and if you want the same entertainment for less, keep the bets straight.
Sources: American Gaming Association, NBER, UCLA Anderson Review
