Three picks at 1.90 and C$10 on it. The parlay calculator above puts that at combined odds of 6.86, so a C$68.59 return. Add a fourth leg at 1.90 and it jumps to 13.03. Looks like free money for one more pick.
It isn’t. Four legs at 1.90 have to all come in, and the prices say that happens less than 8% of the time.
How the parlay calculator adds it up
Combined odds = odds₁ × odds₂ × … × oddsₙ Return = stake × combined odds Implied chance all win = 100 ÷ combined odds
Add or remove legs with the buttons, up to 20. Every leg has to win. One loses, the whole thing loses.
Why bookies love parlays
Every price has a margin in it. A coin-flip game priced at 1.90 on both sides gives the bookie about 5% on a single bet. In a parlay, that margin multiplies.
Say each of your four picks really is 50/50. The fair price for all four would be 16.00. You’re getting 13.03. That’s about 19% of your stake gone on average, against 5% on one single bet. Six legs and it’s over a quarter.
So when the calculator warns you about long parlays, that’s why. It’s not saying don’t do it. Small stakes, big odds, a fun Saturday: fine. Just don’t think of it as the clever way to bet.
Small print to check
Void legs (postponed match, non-runner) are usually dropped and the parlay continues at lower odds. Some books offer parlay insurance or profit boosts, which can actually change the maths in your favour. Read how it works before you count on it.
Decimal or American odds
Most sites show decimal odds, and plenty let you flip to American. The calculator takes either. Three picks at −110 are about 1.909 each in decimal, so the parlay is 1.909 × 1.909 × 1.909 = 6.96. A C$10 parlay pays C$69.58, which works out at roughly +596.
Now compare. Three bets that each really are 50/50 should pay +700 as a parlay. You get about +596. That gap is the book’s margin, three times over. In the UK and Ireland the same bet is called an acca, and the acca calculator handles fractional odds and acca boosts.
Big odds mean small chances. Stake what you’d be fine losing. If it stops being fun, BeGambleAware.org can help.