American Odds Explained: Favorites, Underdogs, and Payouts
American odds describe a payout using a $100 reference amount. This guide explains the sign, the difference between net winnings and total return, and the break-even probability implied by the offered price. The same format can price a moneyline, spread, or total.
Read the Price Before the Team Label
Negative odds such as -150 tell you how much to stake to win $100 in net profit. Positive odds such as +200 tell you the net profit on a $100 stake. +100 and -100 both represent even money.
Favorite and underdog are relative descriptions within a particular market. Both sides can have negative prices, as in -110/-110. A spread underdog can carry a negative price to cover its handicap. In a market with several outcomes, even the shortest-priced selection can have positive odds. The sign alone does not identify which team is more likely to win the game.
Negative Odds: Net Winnings and Total Return
For negative odds A and stake s: net winnings if successful = s × 100 / abs(A). Total return = stake + net winnings. A loss forfeits the stake; a refunded push has zero net profit.
| Offered odds | Stake to win $100 | Implied break-even probability |
|---|---|---|
| -110 | $110 | 52.38% |
| -150 | $150 | 60.00% |
| -200 | $200 | 66.67% |
| -300 | $300 | 75.00% |
| -500 | $500 | 83.33% |
Example, ignoring fees and taxes: a $50 stake at -150 wins $50 × 100/150 = $33.33 net, for $83.33 total return. Values are rounded to cents for display.
Positive Odds: Net Winnings and Total Return
For positive odds A: net winnings if successful = stake × A / 100.
| Offered odds | Net winnings on $100 | Implied break-even probability |
|---|---|---|
| +110 | $110 | 47.62% |
| +150 | $150 | 40.00% |
| +200 | $200 | 33.33% |
| +300 | $300 | 25.00% |
| +500 | $500 | 16.67% |
A $50 stake at +200 wins $100 net, returning $150 including the stake. A larger offered payout says nothing by itself about expected profit.
What the Implied Probability Means
For positive odds: q = 100 / (odds + 100). For negative odds: q = abs(odds) / (abs(odds) + 100). Here q is the raw implied break-even probability: the win rate needed to break even at a fixed price in a win/loss model without fees, taxes, pushes, or voids. It is not a measured true probability.
At -180, q is 180/280 = 64.29%; at +150, q is 100/250 = 40.00%. If those are the two prices for mutually exclusive and exhaustive outcomes, their sum is 104.29%, an overround of 4.29 percentage points.
For normalization and expected-value examples, continue to the worked conversion guide.
Even Money Does Not Mean a Margin-Free Market
A hypothetical +100/-120 two-outcome market has raw probabilities of 50.00% and 54.55%. Their sum is 104.55%, an overround of 4.55 percentage points. One even-money price therefore does not establish that the whole market has no margin.
At -110/-110, each break-even probability is 52.38% and the sum is 104.76%. Overround is a property of quoted prices, not a guarantee of the bookmaker’s realized profit on an event.
Reading Changes and Recording Simulation Results
A move from -110 to -115 raises the break-even threshold. It does not, by itself, reveal betting volume, participant identity, or why an operator changed the price. Record the source and timestamp rather than assigning a cause from the number alone.
OwnTheLines displays scheduled market updates and records simulation selections. A favorite can lose, an underdog can win, and a profitable short sample does not prove calibrated forecasting. Read the offered price and settlement rules before comparing results.
For the broader market overview, read how sports odds work.
Frequently Asked Questions
What do negative American odds mean?
At -150, a $150 stake wins $100 net profit and returns $250 including stake. The sign describes the payout price, not a guarantee of winning or the identity of the game favorite.
What do positive American odds mean?
At +200, a $100 stake wins $200 net profit and returns $300 including stake. A positive price can apply to a moneyline, spread, or total; it does not always identify the less likely team in a multi-outcome market.
How do I calculate implied break-even probability?
For positive odds use 100 / (odds + 100); for negative odds use abs(odds) / (abs(odds) + 100). At -150 the threshold is 60%; at +200 it is 33.33%. These win/loss calculations assume no push, void, fee, or tax.
Does +100 mean there is no bookmaker margin?
No. +100 and -100 both mean even-money payouts and a 50% break-even probability. You need prices for all mutually exclusive, exhaustive outcomes to measure a market's overround. +100 opposite -120 has a 104.55% probability sum and a 4.55 percentage-point overround.