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Parlay Odds Calculator

Multiplies the decimal odds of 2–15 independent legs into the combined parlay (accumulator) price and reports the total payout, profit and implied probability of all legs winning.

When to use

You want the combined odds or payout of a multi-leg parlay, accumulator or multi from the decimal price of each leg.

Do not use when: The legs are correlated (same-game parlays are priced differently by bookmakers), you need a single price converted between formats (use odds-converter), or you want to know whether the bet has positive expected value (use bet-expected-value). Mathematics only; not gambling advice.

Formula

combined_decimal_odds = Π decimal_odds_i; total_payout = stake × combined_decimal_odds; profit = total_payout − stake; implied_probability_percent = 100 / combined_decimal_odds

Assumes the legs are independent events so that their implied probabilities multiply; every leg must win for the parlay to pay. The bookmaker margin of each leg compounds in the combined price. Probability mathematics only; not gambling advice.

Inputs

Parameter	Type	Unit	Required	Description
`decimal_odds`	number_list		yes	Decimal odds of every leg, each greater than 1, e.g. 1.91, 2.10, 1.50. Convert American or fractional prices first with odds-converter.
`stake`	number		default 100	Amount wagered on the whole parlay (any currency). Range: > 0, ≤ 1000000000

Outputs

Output	Type	Unit	Description
`combined_decimal_odds`	number		Product of all leg odds.
`combined_american`	string		The combined price as a signed moneyline, rounded to a whole number.
`total_payout`	number		stake × combined odds (stake included).
`profit`	number		total_payout − stake.
`implied_probability_percent`	number	%	100 / combined odds = product of the legs' implied probabilities.
`legs`	integer		How many selections were combined.

Example

Three legs 1.91, 2.10, 1.50 with stake 100: {"decimal_odds":[1.91,2.1,1.5],"stake":100} → {"combined_decimal_odds":6.0165,"combined_american":"+502","total_payout":601.65,"profit":501.65,"implied_probability_percent":16.62,"legs":3}

Four even-money legs with stake 10: {"decimal_odds":[2,2,2,2],"stake":10} → {"combined_decimal_odds":16,"combined_american":"+1500","total_payout":160,"profit":150,"implied_probability_percent":6.25,"legs":4}

GET https://tttkmbb.com/api/v1/calculate/parlay-odds?decimal_odds=1.91%2C2.1%2C1.5&stake=100

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/parlay-odds (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/parlay-odds · Markdown: https://tttkmbb.com/gaming/parlay-odds.md · JSON definition: https://tttkmbb.com/gaming/parlay-odds.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="parlay-odds"
OpenAPI operationId: calculate_parlay_odds
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Parlay (gambling) (Wikipedia) (reference)
Odds – moneyline, decimal and fractional odds and implied probability (Wikipedia) (reference)

FAQ

Can I enter American or fractional odds?

No, each leg must be in decimal form. Convert -110 (1.909) or 3/2 (2.50) with odds-converter first, keeping at least three decimals.

Why is the implied probability so low?

It is the product of every leg's implied probability, and each leg carries the bookmaker's margin, so the margin compounds with the number of legs.

Related calculators

Odds Converter — Convert each leg to decimal odds before combining.
Probability of Two Events Calculator — Probability that independent events all occur.
Bet Expected Value Calculator — Expected value of the parlay from your own probability estimate.