Series Price Calculator
Calculate fair odds for winning a BO1, BO3 or BO5 series from a per-map win probability, and compare against a bookmaker's offered odds.
Your own estimate of Team A's chance to win a single map — not the whole series.
Fill in one or both fields to see your edge against the bookmaker's price. Leave blank to just see the fair odds.
Enter Team A's per-map win probability to see fair series odds and exact-score prices.
This calculation assumes each map is independent with the same win probability throughout the series, and does not account for side selection, map pool, or momentum between maps. The edge calculation depends entirely on your own estimated per-map win probability.
Pricing a full BO3 or BO5 series takes more than just looking at the odds for a single map — the more maps played, the more a small per-map edge gets amplified (or smoothed out). This calculator turns your estimated per-map win probability into fair series odds for BO1, BO3 and BO5, a full correct-score table, and a comparison against a bookmaker's actual price.
How the series odds are calculated
A BO1 series is trivial — the series win probability is the same as the per-map win probability. In BO3 and BO5, every possible final score (e.g. 2-0, 2-1 in BO3) is priced separately with the binomial "race to N wins" formula, and every outcome where Team A wins is summed into Team A's overall series-win probability.
P(series win) = Σ C(winsNeeded − 1 + k, k) × p^winsNeeded × (1-p)^k · Fair odds = 1 / P · EV per unit = P × bookmaker odds − 1
Your "edge" is the difference between your fair probability and the bookmaker's implied probability (1/odds). A positive EV per unit means the bookmaker's odds pay more than your own estimate justifies — a value bet according to your model. Enter odds for both teams and the calculator also works out the bookmaker's margin on that market.
Worked example
Say you estimate Team A's per-map win probability at 55% in a BO3 series. That gives a fair series-win probability of roughly 57.6% (0.55² × (3 − 2 × 0.55)), which prices out to fair odds of about 1.74. If the bookmaker offers 1.90 on Team A, your edge is positive — the odds pay more than your model says they should.
Frequently asked questions
Why are series odds so different from the odds on a single map?
The more maps played, the more a small per-map edge gets amplified — a favourite with a 55% per-map win probability becomes a clearer favourite to win a full BO3 series, and even clearer over BO5. It's the same reason a coin flip feels more predictable the more times you flip it.
What does a positive EV per unit mean?
A positive EV per unit (e.g. +0.05) means the bookmaker's offered odds return, on average, 5 cents more per unit staked than your own model considers fair, assuming your win-probability estimate is accurate. It's only ever as good as the estimate you enter.
Can I use this calculator to find arbitrage between two bookmakers?
Not directly — this calculator compares a bookmaker's odds against YOUR OWN estimated probability, not against another bookmaker's odds. To find a guaranteed arbitrage between two operators, use the hedge calculator or margin calculator instead with the actual odds from both sides.
