Parlay calculator
True parlay odds, leg by leg.
Last updated 2026-07-03
Enter each leg in American odds and your stake. You get the combined true odds, total payout, and the parlay's implied probability. Compare the true odds against what your book offers.
How it works
Each leg converts to decimal odds; the parlay's decimal odds are the product of all legs. Payout = stake x combined decimal. Implied probability = 1 / combined decimal. Because every leg carries vig, the book's hold compounds with each leg you add: parlays are priced worse than the same money on singles.
Same-game parlays are correlated and books price them with correlation models. Simple multiplication overstates true odds for correlated legs.
Do this programmatically
Price parlays from live single-leg markets: pull decimal odds and multiply. Best available price per leg comes straight from the best-lines endpoint:
curl "https://api.theoddsapi.com/best-lines/?sport_key=baseball_mlb&oddsFormat=decimal" \ -H "x-api-key: YOUR_API_KEY"
Line-shopping each leg across 50+ books before parlaying is the single biggest payout improvement available. Free key in minutes.
Questions
Is a parlay ever +EV?
Only if the individual legs are +EV, and even then singles usually carry the edge more efficiently. If you have devigged fair probabilities per leg (see the no-vig calculator), the parlay's fair probability is their product; compare that to the offered price.
Why does my book's parlay payout differ from this calculator?
Rounding, per-leg price shading, or correlation adjustments on same-game legs. If the book's offer is meaningfully below the multiplied true odds, that gap is extra margin they are charging.
More tools: Odds converter · No-vig fair odds · Arbitrage · CLV