Parlay / Accumulator Calculator

What is a parlay / accumulator?

A parlay (or accumulator / acca) is a single bet that combines two or more individual selections. All legs must win for the bet to pay out — if any leg loses, the entire parlay is lost.

The appeal is the multiplied payout: because odds compound with each leg, even a few moderate-priced selections can produce a large combined return on a small stake.

• Called a parlay in the United States and Canada
• Called an accumulator (acca) in the UK, Ireland, and most of Europe
• Called a multi in Australia
• Extremely popular in football (soccer) betting — weekend accas are a major product for UK bookmakers

Higher reward comes with proportionally higher risk: the probability of winning drops with each additional leg. A 5-team parlay where every team has a 60% win chance has only a 7.8% probability of winning in total.

How parlay odds are calculated

Parlay odds are computed by multiplying all leg odds together (decimal format):

Example: Three legs at 1.80, 2.10, and 1.90:

This is why parlays are attractive: individually unspectacular odds (1.80–2.10) produce a 7× combined return. The trade-off is that all three teams must win.

In American odds format, sportsbooks typically recalculate rather than strictly converting — always verify payout with the actual ticket from your sportsbook.

Why parlays have negative expected value

Each leg offered by a bookmaker includes a margin (vig / overround). When you combine legs into a parlay, the house edge compounds:

• A single leg with 5% vig costs you 5%
• A 2-leg parlay compounds to roughly 9.75% effective vig
• A 3-leg parlay compresses to roughly 14.3%
• A 5-leg parlay results in approximately 22.6% effective vig

Professional bettors generally avoid parlays unless every individual leg has independently verified positive expected value. A parlay of negative-EV legs is worse than betting each leg individually — the edges stack the wrong way.

Exception — correlated parlays: Some books allow parlays on outcomes from the same match that naturally correlate (e.g., a team to win and over 2.5 goals in the same game). When outcomes correlate positively, the theoretical fair value of the combined bet exceeds the product of individual odds. A minority of sportsbooks will accept these; most explicitly ban same-game parlays on correlated outcomes.

Use the EV calculator on each individual leg before building your parlay — if any leg is negative EV, the parlay is likely to be even worse EV overall.

American sportsbook parlay payouts — standard reference

Standard American sportsbooks use -110 lines (52.38% implied probability per leg). The table below compares typical sportsbook payouts versus the mathematically fair payout:

Fair payout assumes -110 lines with zero margin. The gap widens dramatically with more legs — a 5-leg parlay at a typical sportsbook returns roughly half the mathematically fair amount.