Esports Series Probability Calculator
Calculate exact win probabilities for BO3, BO5, and BO7 series. Model map score distributions, upset potential, and adjust live betting lines mid-series with conditional probability math.
Series Parameters
Books price the series, not the map. A series price is converted back to the per-map rate it implies for this format, so the result can be compared against it rather than derived from it.
Series Analysis
Map Score Distribution
Live Series Simulator
Set the current map score to calculate updated conditional probabilities for live betting adjustments.
Remaining Outcomes from 0-0
Format Comparison
See how different series lengths affect win probability at your current per-map win rate of 55.0%.
| Format | Series Win % | Exp. Maps | Sweep % | Distance % | Upset Amplification | Fair Odds |
|---|---|---|---|---|---|---|
| BO1 | 55.0% | 1.00 | 55.0% | 100.0% | +0.0% | 1.818 |
| BO3 | 57.5% | 2.50 | 30.3% | 49.5% | +2.5% | 1.740 |
| BO5 | 59.3% | 4.11 | 16.6% | 36.8% | +4.3% | 1.686 |
| BO7 | 60.8% | 5.78 | 9.2% | 30.3% | +5.8% | 1.644 |
Sensitivity Analysis
How series win probability changes across different per-map win rates for the selected BO3 format.
Map Ban Phase Simulator
Simulate the BO3/BO5 map veto. Click maps to ban or pick them in turn. See your expected series win probability after bans.
Historical H2H Series Data
Enter historical head-to-head series results. The tool Bayesian-updates your win probability using observed data as a likelihood against the prior.
How It Works
Negative Binomial Distribution
A BO(2n-1) series ends when one team reaches n wins. The probability of a specific final score uses the negative binomial distribution: the number of maps needed for the n-th success, given independent map outcomes with fixed probability p.
Series Length Amplification
Longer series amplify skill edges. A team with 55% per-map win rate has 57.6% in a BO3, 59.3% in a BO5, and 60.8% in a BO7. This is why top-tier tournaments use BO5 finals: they reward consistency and reduce variance.
Live Conditional Probability
Once maps are played, the remaining series becomes a shorter best-of. Being up 1-0 in a BO3 means you only need 1 more win while your opponent needs 2. This dramatically shifts probabilities and creates live betting opportunities when markets are slow to adjust.
Map Veto Advantage
In CS2 and Valorant, teams pick and ban maps, creating asymmetric probabilities. A team might have 65% win rate on their pick but only 40% on the opponent's pick. Accounting for map veto advantage produces more accurate series predictions than using a single flat win rate.
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