Parlays combine multiple bets into one ticket. If every leg wins, you get a bigger payout than if you bet each game separately. But how are those payouts calculated? This guide walks you through the math step by step, using American, decimal, and fractional odds.
Whether you're building a 2-leg same-game parlay or a 5-leg cross-sport ticket, understanding the numbers helps you evaluate risk, compare books, and avoid common mistakes. Explore more betting guides on SportBusy.
What is a parlay?
A parlay (also called an accumulator or combo bet) is a single wager that links two or more individual bets. All legs must win for the parlay to cash. If even one leg loses, the entire bet loses.
Examples:
- A 2-leg parlay: Lakers moneyline + Celtics -3.5 spread
- A 3-leg parlay: Chiefs -7, Over 47.5, Travis Kelce anytime TD
- A same-game parlay: All bets from one NFL or NBA game
- A cross-sport parlay: NBA + NHL + MLB on one ticket
Parlays are popular because they offer higher potential payouts than betting each game individually. The tradeoff: one loss wipes out the whole ticket.
The math: how parlay odds multiply
The core idea: parlay payouts are calculated by multiplying the decimal odds of each leg. If you have three legs at 2.00, 2.50, and 1.80, the combined parlay odds are:
2.00 × 2.50 × 1.80 = 9.00
So a $100 bet would return $900 total ($800 profit + $100 stake). This multiplication method works in decimal odds. American and fractional odds must be converted first—which we'll cover below.
Step-by-step: calculating a 2-leg parlay with American odds
Let's say you bet a 2-leg parlay:
- Lakers moneyline: -150
- Bills spread: -110
Step 1: Convert each American odd to decimal.
- For negative odds: decimal = 1 + (100 / |odds|) → -150 → 1 + (100/150) = 1.667
- For positive odds: decimal = 1 + (odds / 100)
So: -150 → 1.667, -110 → 1.909.
Step 2: Multiply the decimals: 1.667 × 1.909 = 3.18
Step 3: Apply to your stake. $100 × 3.18 = $318 total return ($218 profit).
If you prefer to skip the math, use our free Parlay Calculator.
Step-by-step: calculating a 3-leg parlay
Same process—convert, multiply, apply.
Example: Chiefs -200, Over 45.5 at -110, Cowboys +150.
Step 1 – Convert to decimal:
- -200 → 1 + (100/200) = 1.50
- -110 → 1 + (100/110) = 1.909
- +150 → 1 + (150/100) = 2.50
Step 2 – Multiply: 1.50 × 1.909 × 2.50 = 7.16
Step 3 – Payout: $100 stake × 7.16 = $716 total return ($616 profit).
Converting American odds to decimal for parlay math
Quick reference formulas:
- American negative (e.g., -150): Decimal = 1 + (100 ÷ |odds|)
- American positive (e.g., +200): Decimal = 1 + (odds ÷ 100)
Common conversions:
- -110 → 1.909
- -150 → 1.667
- -200 → 1.50
- +100 (evens) → 2.00
- +150 → 2.50
- +200 → 3.00
Need to convert on the fly? Use our Odds Converter.
Risk vs reward: why parlays are popular but risky
Parlays attract bettors because the potential payout is large relative to the stake. A 5-leg parlay at -110 each leg can pay 25-to-1 or more. That's enticing.
The catch: books typically offer worse parlay odds than the true multiply. A true 2-leg parlay at -110 each would pay about +264; many books pay +260 or less. The house edge compounds with each leg.
Statistically, parlays have higher variance. One bad beat kills the whole ticket. Many sharp bettors prefer straight bets or smaller parlays (2–3 legs) where the math is more favorable.
Common parlay mistakes to avoid
- Chasing big payouts: Adding legs just to increase payout often lowers EV.
- Ignoring correlation: Correlated legs (e.g., team win + Over) can get you reduced or voided odds.
- Not shopping lines: Half-point differences on spreads matter; compare odds across books.
- Overvaluing "sure things": Heavy favorites (-300, -400) barely move parlay payout but add real risk.
- Skipping the math: Always verify your potential payout before placing. Use our Payout Calculator for quick checks.
Correlated parlays and same-game parlays
Correlation means one result affects another. Examples: team to win + Over (if they win big, Over likely hits); quarterback passing yards + team total Over.
Many books restrict or reduce correlated parlay combinations. Same-game parlays (SGPs) are built around correlation—all legs from one game. Books love them because they can set custom odds that favor the house.
If you play SGPs, understand that the odds are often less favorable than the "true" multiply. Treat them as entertainment with known negative EV unless you have a strong edge.
Use the right tools
Calculating parlay payouts by hand gets tedious. SportBusy offers free tools to do it instantly:
- Parlay Calculator – Enter your legs (American, decimal, or fractional) and see exact payout.
- Odds Converter – Switch between American, decimal, and fractional.
- Payout Calculator – Check single-bet and parlay payouts.
- Schedule – Find upcoming games and compare lines.
Try our free Parlay Calculator to see your exact payout before you place any parlay.
FAQ
How do you calculate a 2-leg parlay payout?
Convert each leg from American to decimal odds, multiply the decimals, then multiply by your stake. Example: -150 (1.667) × -110 (1.909) = 3.18. $100 × 3.18 = $318 return.
What is the formula for parlay odds?
Parlay decimal odds = Leg1(decimal) × Leg2(decimal) × Leg3(decimal) × … for all legs. Total return = stake × parlay decimal odds.
Do parlay odds multiply or add?
Parlay odds multiply. Each leg's decimal odds are multiplied together. The result is your combined parlay decimal odd.
Why do parlays pay less than true odds?
Sportsbooks build margin into each leg and often apply additional parlay rules (e.g., reduced payouts on correlated legs). The "true" multiply would be fair; books typically pay slightly less.
Are same-game parlays a good bet?
Same-game parlays are fun but usually offer worse value than straight bets. The odds are often worse than true multiplied odds. Treat them as entertainment unless you have a clear edge.
Where can I find a free parlay calculator?
SportBusy offers a free Parlay Calculator that supports American, decimal, and fractional odds. Enter your legs and stake to see your exact potential payout.