I built this because I've struggled with gambling myself. Seeing the numbers laid out made it hard to argue with. I wasn't unlucky. The math was always going to win.
If you ended up here by accident, I hope it saves you some of what it cost me.
Ten reasons not to bet
It all comes down to math and how our brains work. Each tool below lets you check it yourself.
You need to win more than half just to break even
At -110 you have to win 52.4% of your bets to come out even. If you win exactly half, you lose about 4.5 cents of every dollar you bet. Check a line.
Parlays cost the most
Every leg adds its own fee, and the fees stack. A 6-leg parlay at -110 per leg costs you about 24 cents of every dollar. Books push these the hardest. See what each leg costs.
Same-game parlays and props usually cost even more
Legs from the same game are linked, and books price that in their favor. Props also tend to have bigger margins than point spreads. Expect a higher fee, not a lower one.
Long shots cost the most
A big payout on a small chance usually carries a bigger margin than a favorite does.
More bets means a surer loss
Your expected loss grows with every bet you place. Luck evens out over time, but the fee doesn't. Watch 2,000 bettors.
Early wins are mostly luck
After 100 coin-flip bets, about a third of bettors are ahead. After 5,000, almost none are. A hot start doesn't mean you're good at this.
Winning gets you limited
Bettors who win consistently often get their limits cut or their accounts closed. The books want customers who lose.
Free bets and bonuses don't change the math
A promo can be worth something once. The fee is still on every bet you place to use it, and every bet after.
Your brain misreads what's happening
A near-miss feels like almost winning. You remember the wins and forget the losses. Raising your stakes to win it back turns a small loss into a big one. This happens to a lot of people.
That money could go somewhere else
Left alone, the same money adds up. See what your betting costs per year, and what that could have grown to.
1. What does this line really cost?
Enter the odds for both sides of a bet. For a point spread that's usually -110 and -110.
How it works: each price turns into an implied probability. The two sides should add up to 100%. Whatever is over that is the book's cut. Hold = 1 − 1 / (sum of implied probabilities).
2. What does each extra leg cost?
Add legs and watch the expected loss climb. This assumes each leg is a true 50/50 before the fee, which is generous.
3. Check your slip before you place it
Enter the odds for each leg of your parlay. You'll see how often the whole thing wins and what it costs you.
How it works: each leg's price turns into a chance, then the fee comes off to get a fair chance (fair chance = implied chance × (1 − fee)). The slip only wins if every leg does, so the chances multiply. 4.5% is typical for a spread or total. Props, same-game parlays and lopsided moneylines often have more, so raise the fee if that's what you're betting. Legs from the same game are linked, which books price in their favor, so treat this result as the best case.
4. How often do I need to win to break even?
Enter the odds you usually bet at.
5. What happens to 2,000 people betting like you?
Every simulated bettor makes the same bets at the same odds. You pick the win rate. The default is a coin flip before the fee. Try raising it to see how good you'd have to be.
How it works: each bet wins with the probability you set and pays at the odds you entered. 2,000 bettors are simulated. The shaded band is the middle 80% of outcomes, the red line is the median, and the thin lines are the luckiest and unluckiest 1%. Each run comes out a little different. The pattern doesn't change.
6. What is it costing me per year?
Your betting as a yearly cost, and what that money could grow to if you saved it instead.
How it works: expected loss = amount bet × fee. Use about 4.5% for single bets and 15-25% for parlays. The savings number is an assumption, not a promise. Returns vary and can be negative.
“But some people do win”
A few do. They usually find prices that are out of date, or shop lines across lots of books, and then get limited or banned once they start winning. To come out ahead you'd need a win rate above the break-even number over thousands of bets. The simulator shows how rare that is.
“Bonuses are free money.” One promo can be worth something. The fee is still there on every bet after it.
“It's just for fun.” That's fine, as long as you know what it costs. The cost calculator shows the price per year.