Accumulator (Parlay) 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
• Common in football (soccer) betting

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 compounds to roughly 14.3%
• A 5-leg parlay results in approximately 22.6% effective vig

Value 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. Most bookmakers now offer bet builders for same-match selections and price the correlation in, usually with a higher margin than singles.

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.