How to Read Betting Odds (2026)
Three formats, one idea: every odds price is a probability with the sportsbook margin baked in. Once you can convert a price to a probability, everything else in betting gets easier.
The three formats
American uses plus and minus. −150 means risk $150 to win $100, a favourite. +150 means a $100 stake profits $150, an underdog.
Decimal shows total return per $1 staked including the stake. 2.50 returns $2.50 on a $1 bet.
Fractional shows profit against stake. 3/2 wins $3 for every $2 risked. Common in the UK and horse racing.
Conversion table
| American | Decimal | Fractional | Implied probability |
|---|---|---|---|
| −300 | 1.33 | 1/3 | 75.0% |
| −200 | 1.50 | 1/2 | 66.7% |
| −150 | 1.67 | 2/3 | 60.0% |
| −120 | 1.83 | 5/6 | 54.5% |
| −110 | 1.91 | 10/11 | 52.4% |
| −105 | 1.95 | 19/20 | 51.2% |
| +100 | 2.00 | 1/1 | 50.0% |
| +110 | 2.10 | 11/10 | 47.6% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +300 | 4.00 | 3/1 | 25.0% |
| +500 | 6.00 | 5/1 | 16.7% |
The formulas. Negative American odds: the absolute value divided by (that value plus 100). Positive: 100 divided by (the odds plus 100). So −150 implies 60%, and +150 implies 40%.
The vig: why both sides add up to more than 100%
Add the implied probabilities of both sides of a market and you get more than 100%. The excess is the sportsbook margin.
| Market | Implied total | Overround | Book hold |
|---|---|---|---|
| −110 / −110 | 104.76% | 4.76% | 4.55% |
| −105 / −105 | 102.44% | 2.44% | 2.38% |
| −120 / +100 | 104.55% | 4.55% | 4.35% |
Two terms worth separating, because most explanations blur them. The overround is how much the implied probabilities exceed 100%. The hold is the share of total stakes the book expects to keep. At −110/-110 those are 4.76% and 4.55%.
A standard −110 market costs you 4.55% of everything you risk. The same market priced at −105 costs 2.38%. Line shopping roughly halves the vig.
What this means for you
Break-even at −110 is 52.38%, not 50%. That is the number every betting decision sits on top of. A bettor winning 52% at −110 is not marginally ahead, they are losing.
| Price | Break-even win rate |
|---|---|
| −105 | 51.22% |
| −110 | 52.38% |
| −120 | 54.55% |
| −130 | 56.52% |
Which is why the price you get matters as much as the pick. Getting −120 where someone else got −110 raises your required win rate by more than two full points, enough to erase most realistic edges. What that costs when you tail someone else's pick.
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Frequently Asked Questions
What do plus and minus mean in betting odds?
Minus marks a favourite and shows the stake required to win $100. Plus marks an underdog and shows the profit on a $100 stake.
How do I convert odds to implied probability?
For negative American odds, divide the absolute value by itself plus 100, so −150 gives 150 divided by 250, which is 60%. For positive odds, divide 100 by the odds plus 100, so +150 gives 100 divided by 250, which is 40%.
What is the vig?
The sportsbook built-in margin, which is why both sides of a market add to more than 100%. At −110 on both sides the overround is 4.76% and the book expected hold is 4.55% of everything staked.
What win rate do I need to break even?
At −110, 52.38%. At −105, 51.22%. At −120, 54.55%. Anything below the line for the price you are getting loses money over time.
Does shopping for a better price actually matter?
Substantially. The same market at −105 instead of −110 cuts the book hold from 4.55% to 2.38%, roughly half the margin, on every bet you place.
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