Filling a slip for "What are decimal odds?" starts with one ticket. A parlay, called an accumulator in many places, joins several picks into one bet. Every leg has to win for the ticket to pay, and the odds of the legs multiply, so a small stake can return a large sum. What makes the format attractive is the same thing that makes it hard: each added leg lowers the chance that the whole bet comes in.
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A push, where a spread or a total lands exactly on the line, does not win a parlay and does not lose it. Most books treat a pushed leg like a void one: it leaves the ticket, and the parlay pays on the legs that remain. To define a same game parlay simply: several picks from one match on one ticket. Because those picks are linked, the book prices the combination itself, and its margin on a same game ticket is wider as a rule.
Can parlays be profitable over a long run? Rarely. Each leg carries the book's margin, and multiplying legs multiplies the margin as well, so a four leg accumulator hands the house far more edge than four single bets would. Accumulator bets are worth it as entertainment priced in advance, a small stake on a long shot. Anyone who treats them as a way to earn is paying the widest margin on the whole menu.
A parlay works by multiplication. Each leg carries its own odds, and the payout on a parlay is the stake times the decimal odds of every leg multiplied together. Three legs at 2.0 each turn one unit into eight. The same arithmetic runs the other way for the chance of winning: three picks that each land half the time win together only one time in eight, and the price offered usually pays less than the fair eight.
Yes. The same picks placed as single bets carry far less combined margin, which shows how much edge the accumulator hands the house.
Most books drop that leg from the ticket, and the parlay pays at reduced odds on the legs that remain.
A round robin splits a list of picks into every smaller parlay, such as doubles or trebles, costing one stake per combination so a single loss does not sink everything.
A bet that reverses the usual logic and pays out when at least one of the selected legs loses.