# \$500 on GSP FTWJanuary 27, 2009 12:50 PM   Subscribe

How do I make sense of the "moneyline" form of betting odds for mixed martial arts?

I'm trying to understand the way that betting on mixed martial arts works. I have read the description here, so I think I have the basics down. But I'm curious about one thing. The opening line for the GSP/BJ Penn fight is Georges St-Pierre -245 vs. B.J. Penn +175. If I understand this correctly, this means that a \$245 bet on GSP results in a \$100 profit, and a \$100 bet on Penn results in a \$175 profit.

My question is, why can't a savvy bettor hedge and come out ahead every time? For example, say I bet \$100 on both fighters:

If GSP wins I win \$140.82 and lose \$100 to net \$40.82.
If Penn wins, I win \$275 and lose \$100 to net \$175.

So I come out ahead no matter who wins. This cannot be right; there is no way that I have stumbled on a foolproof moneymaking scheme. So what am I missing? Hidden commissions on placing bets? Have I misunderstood the explanation? Is my math bad? Do I need more caffeine today?
posted by googly to Sports, Hobbies, & Recreation (6 answers total) 1 user marked this as a favorite

Your math for GSP winning is wrong. Your first \$100 results in nothing, and your second results in \$140.82, not \$240.82, so you end up with only \$140.82 out of your original \$200.

The sanity check is that if the GSP bet paid out \$140.82 in profit on a \$100 bet, you would be getting better than even money odds (1:1=\$100 in profit), and it wouldn't make sense for both of the bets to pay out better than even money. The negative side of a moneyline bet is by definition worse than even money odds.
posted by burnmp3s at 1:13 PM on January 27, 2009

Also, your net calculation for Penn is wrong. You walk away with \$275 after risking \$200, so you only have \$75 more than you started with after both bets.
posted by burnmp3s at 1:23 PM on January 27, 2009

Thanks. I figured that must be it, but the explanation at the website I linked said "so if you were to bet \$140 on Tito, you’d win \$100 (profit) if he is victorious..." which sounded like a profit of \$100 on a \$140 bet, not a total payout of \$100 on a \$140 bet. I think that's what threw me off.
posted by googly at 1:30 PM on January 27, 2009

I figured that must be it, but the explanation at the website I linked said "so if you were to bet \$140 on Tito, you’d win \$100 (profit) if he is victorious..." which sounded like a profit of \$100 on a \$140 bet, not a total payout of \$100 on a \$140 bet. I think that's what threw me off.

No, your thinking was correct there, you just didn't adjust correctly for a smaller bet. You said that a \$245 bet on GSP results in a \$100 profit and then later If GSP wins [on a \$100 bet] I win \$140.82. So according to your calculation, a \$100 bet would actually pay out more than a \$245 bet. To put it another way, if you want a chance to win a profit of more than \$100 on GSP, you'll have to bet more than \$245, and if you bet less than \$245 your possible payout will be reduced to under \$100.
posted by burnmp3s at 1:47 PM on January 27, 2009

Oh my god I am an idiot. Got it now. Thanks!
posted by googly at 1:49 PM on January 27, 2009

The easy way to remember this is think about it in increments of \$100

A negative moneyline is how much money you must bet to win \$100
And a positive moneyline is how much money \$100 will get you

So -245 = bet \$245 to take \$100
+175 = bet \$100 to take \$175
posted by jckll at 2:17 PM on January 27, 2009

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