What does +/- mean in betting?
The plus and minus signs you see next to every American sports betting line, explained — including how to convert them into the probability a bet actually wins.
The short answer
In American odds, the − (minus) sign marks the favorite and the + (plus) sign marks the underdog.
- −150 means you must risk $150 to win $100.
- +150 means you risk $100 to win $150.
The number is always relative to $100. You can scale it to whatever stake you want — at −150, a $30 bet wins $20; at +150, a $30 bet wins $45.
Why two formats?
American odds (+/−) are the standard in North American sportsbooks. Two other formats you'll see elsewhere on the internet are decimal odds (e.g. 2.50) and fractional odds (e.g. 3/2). They all describe the same payout — just in different notations.
| American | Decimal | Implied win % |
|---|---|---|
| −200 | 1.50 | 66.7% |
| −150 | 1.67 | 60.0% |
| −110 | 1.91 | 52.4% |
| +100 (even) | 2.00 | 50.0% |
| +150 | 2.50 | 40.0% |
| +200 | 3.00 | 33.3% |
Converting American odds to implied probability
The "implied probability" column above is the bookmaker's estimated chance a bet wins (with the vig included). Two formulas:
- For minus odds (e.g. −150):
−odds / (−odds + 100). So −150 → 150 / 250 = 60%. - For plus odds (e.g. +150):
100 / (odds + 100). So +150 → 100 / 250 = 40%.
These are the percentages your bet has to actually win at to break even after the bookmaker's vig. Anything above is +EV (profitable long-term); anything below is −EV.
Why most lines look like −110
On standard markets (point spread, total over/under), both sides usually price at −110. That's not a coincidence — it's how the sportsbook builds in its margin.
If a coin flip really paid out fairly, both sides would price at +100 (even money). Setting both sides to −110 means you need ~52.4% to break even instead of 50%. That 2.4% gap is the house edge, also called the vig or juice.
How this fits into the bigger picture
Picking the right side is only half the game — picking the right price is the other half. A pick at −300 needs to win 75% of the time just to break even. The same pick at +120 only needs 45.5%. Same team, very different outcomes.
That's why Wagerly's AI looks at the gap between the model's projected win probability and the bookmaker's implied probability. When the gap is positive, the bet is +EV. When it isn't, the bet gets filtered out — even if the AI thinks the pick will win.
Frequently asked questions
Does a + always mean an underdog?
On a head-to-head matchup, yes — the + side is always the underdog and the − side is the favorite. On a point spread, both sides are usually priced near −110 because the spread itself is doing the work of evening them out.
Is +200 better than +150?
+200 pays more if it wins ($200 on a $100 bet vs. $150), but it also wins less often — about 33% implied vs. 40%. Higher plus odds always pay more and win less often.
What does −110 actually pay?
A $110 bet at −110 pays $100 in profit (you get $210 back including stake). That's the standard 'lay 11 to win 10' price.
Where can I see Wagerly's picks with the odds?
On the daily AI picks page and inside the AI Stats dashboard. Both show the AI's moneyline and totals predictions for every game.