Bettor Ed Parlay Odds Calculator

• What does the Parlay Odds Calculator do?

  • The Parlay Odds Calculator is a free sports betting tool that calculates the true probability and fair odds for a parlay.

  • It takes the American odds from multiple selections, converts each into its implied probability, and multiplies them to find the combined chance of winning the entire parlay.

  • Finally, it converts that total probability back into fair American odds, giving you a transparent look at what the parlay should pay before the sportsbook’s margin is added. It’s ideal for U.S. bettors using FanDuel, DraftKings, BetMGM, or BetOnline who want to verify whether their parlay payouts are fair.

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• How do you calculate fair parlay odds?

  • Here’s the exact process our calculator uses to determine vig-free parlay odds:

  • Step 1: Convert each leg’s odds to implied probability

    • For positive odds (e.g., +200):
      Probability = 100 / (Odds + 100)

    • For negative odds (e.g., -150):
      Probability = |Odds| / (|Odds| + 100)

  • Step 2: Multiply all probabilities together

    • This gives the combined parlay probability — the true chance of all legs winning.

  • Step 3: Convert the total probability back to American odds

    • If the parlay probability is greater than 0.5:
      Fair Odds = −(Probability / (1 − Probability)) × 100

    • If it’s 0.5 or less:
      Fair Odds = ((1 − Probability) / Probability) × 100

  • The result shows the fair, no-vig parlay odds, which can differ significantly from what sportsbooks post.

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• How can this Parlay Odds Calculator benefit me?

  • Sportsbooks often shade parlay odds — meaning the payouts they offer are slightly worse than the true mathematical price. By comparing your sportsbook’s payout to the calculator’s fair odds, you can instantly tell whether your parlay offers positive expected value (EV) or is overpriced.

  • This tool helps bettors shop lines smarter, avoid poor-value parlays, and understand how vig affects payouts.

  • Whether you’re building a small two-leg parlay or a large multi-leg bet, it ensures you’re betting with clarity and not leaving value on the table.​​

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