Parlay Probability Calculator
Calculate the probability of a parlay winning and the margin embedded in it.
About Parlay Probability Calculator
Multiplying probabilities means adding legs reduces the win chance geometrically. Comparing fair odds with the odds offered reveals the margin, which compounds with each leg added. The independence assumption often fails in practice, since correlated legs such as two outcomes in the same match make the true probability differ from the product.
Formula
Parlay Probability
Parlay probability = the product of the individual probabilities, assuming independence
- fair odds
- The reciprocal of the true probability
- independence
- Assumes each leg’s outcome does not affect the others
Worked example
With the default values below, Parlay Probability Calculator returns Probability of Winning of 10.6163%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Leg 1 true probabilityaccepts 0.01–100 %
- 58 %
- Leg 2 true probabilityaccepts 0.01–100 %
- 52 %
- Leg 3 true probabilityaccepts 0.01–100 %
- 64 %
- Leg 4 true probability, 100 if unusedaccepts 0.01–100 %
- 55 %
- Combined odds offeredaccepts 1.01–10,000
- 9.5
Results
- Probability of Winning
- 10.6163%
- Fair Decimal Odds
- 9.4195
- Expected Value per Unit Staked
- 0.855%
- Bookmaker Edge
- -0.855%
- Verdict
- Positive expected value at these odds
Step by step
- 1Values used
- 2Parlay Probability
- 3Probability of Winning= 10.6163
- 4Fair Decimal Odds= 9.4195
- 5Expected Value per Unit Staked= 0.855
- 6Bookmaker Edge= -0.855
- 7Verdict= Positive expected value at these odds
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- These figures are estimates based on population-average formulas and are intended for training and recreational planning only. They are not medical advice. Consult a qualified health professional before starting or changing an exercise programme, particularly if you have an existing medical condition.
- This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
These figures are estimates based on population-average formulas and are intended for training and recreational planning only. They are not medical advice. Consult a qualified health professional before starting or changing an exercise programme, particularly if you have an existing medical condition.
Frequently Asked Questions
How is Parlay Probability calculated?
Parlay probability = the product of the individual probabilities, assuming independence Multiplying probabilities means adding legs reduces the win chance geometrically. Comparing fair odds with the odds offered reveals the margin, which compounds with each leg added.
Why does Parlay Probability matter?
The independence assumption often fails in practice, since correlated legs such as two outcomes in the same match make the true probability differ from the product.
What values do I need to enter?
This calculator takes 5 inputs: Leg 1 true probability, Leg 2 true probability, Leg 3 true probability, Leg 4 true probability, 100 if unused, Combined odds offered. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.