How is clean sheet probability calculated?

Clean sheet probability = e^(-xG). This comes from the Poisson distribution: P(goals = 0) = e^(-λ) × λ^0 / 0! = e^(-λ). If a team has 1.5 xG, their clean sheet probability is e^(-1.5) = 22.3%. The formula is exponential — a team with 2.0 xG has only a 13.5% chance of keeping a clean sheet.

What does BTTS mean in betting?

BTTS (Both Teams to Score) means both teams score at least one goal each. The probability is the product of each team's scoring probability: (1 - e^(-homeXG)) × (1 - e^(-awayXG)). If both teams have high xG, BTTS is more likely.

Poisson xG

Clean Sheet Probability

Calculate clean sheet, BTTS, and 0-0 draw probabilities using the Poisson-xG model. See fair odds for all outcomes.

Home xG (Expected Goals)

Sum of home team's shot xG values

Away xG (Expected Goals)

Sum of away team's shot xG values

Home Clean Sheet

22.3%

Away Clean Sheet

30.1%

BTTS

93.3%

0-0 Draw

6.7%

Fair Odds (Home CS)

4.48

Fair Odds (Away CS)

3.32

Fair Odds (BTTS)

1.07

Fair Odds (0-0)

14.88

Probability Split

Home Clean Sheet22.3%

Away Clean Sheet30.1%

BTTS (Both Score)93.3%

0-0 Draw6.7%

How Clean Sheet Probability Works

Clean sheet probability is derived directly from the Poisson distribution. The probability of a team conceding exactly 0 goals given their expected goals against (xG) is:

P(CS) = e^(-xG)

Home Clean Sheet = e^(-homeXG)
Away Clean Sheet = e^(-awayXG)
BTTS = (1 - e^(-homeXG)) x (1 - e^(-awayXG))
0-0  = e^(-homeXG) x e^(-awayXG) = e^(-(homeXG + awayXG))

Example: homeXG = 1.5, awayXG = 1.2
  Home CS: e^(-1.5) = 22.3%     Fair Odds: 4.48
  Away CS: e^(-1.2) = 30.1%     Fair Odds: 3.32
  BTTS: (1 - 0.223) x (1 - 0.301) = 54.3%
  0-0: 0.223 x 0.301 = 6.7%     Fair Odds: 14.9

The clean sheet formula highlights how quickly defensive probability drops as xG increases. A team facing 2.0 xG has only a 13.5% chance of keeping a clean sheet. This exponential relationship makes clean sheet markets particularly sensitive to xG estimates.

Strategy tip: Bookmakers often undervalue clean sheet odds for strong defensive teams. If your xG model shows a team facing significantly less xG than the market implies, the clean sheet market may offer positive EV.