A parlay is the North American name for what British bettors call an accumulator — a single bet combining multiple selections (called "legs") where all must win. Each leg's return rolls onto the next, with odds multiplying across the whole bet. A parlay pays significantly more than the same selections bet individually, but one losing leg eliminates the entire bet.
Parlay mechanics: stake × Odds1 × Odds2 × Odds3 × ... = total return. A three-team parlay on NBA games at -110 each (approximately 1.909 decimal) gives combined odds of 1.909³ ≈ 6.97. A $10 three-team parlay returns approximately $69.70 if all three games go your way.
Parlay odds vs true odds: sportsbooks offer slightly less than the mathematically correct parlay odds due to the margin on each leg. American sportsbooks often use a fixed parlay payout table rather than calculating exact multiplied odds, sometimes making the margin worse at larger leg counts.
Teaser bets are a variant of parlays where you move the point spread in your favour (e.g. by 6 points in NFL) in exchange for lower combined odds. They are popular in football and basketball betting.
Same-Game Parlays (SGP) combine markets from a single game — equivalent to bet builders in European sports betting. Correlation between legs (e.g. a quarterback throwing touchdowns and the team covering the spread) means SGP odds are often less favourable than they appear.
Example
NFL Sunday: you parlay the Chiefs -3.5 (-110), Eagles -1.5 (-115), and Bills +7.5 (-110). All three bets must cover. If all three cover, a $20 parlay at these odds returns approximately $130-$140. If the Bills fail to cover by the spread, the entire parlay loses, even though the other two bets were correct.