Probabilities and fair odds
- Maths reviewed by Josh Miller
- Tested by Diana Westfield
A correct score calculator turns two numbers into a full grid of scorelines. Give it 1.6 expected goals for the home side and 1.1 for the away side and it says 1-1 is the single most likely result at 11.8%, 1-0 next at 10.8%, then 2-1 at 9.5%. That last one is fair at about 10.6. If a bookmaker offers 9/1 (10.0), the price is slightly short. Free, and you can check any score you like.
How the correct score calculator works
Football goals behave a lot like a Poisson process: rare, fairly random events with a known average. So the chance the home team scores exactly 2 when it averages 1.6 is e−1.6 × 1.6² ÷ 2! = 25.8%. The chance the away side scores exactly 1 at 1.1 is 36.6%. Multiply them and you get 2-1: 9.5%.
Do that for every pair and you have the grid above. Green cells are home wins, grey draws, blue away wins, and the stronger the colour, the likelier the score.
Where to get expected goals
The xG figure is the input that matters, so spend your effort there. Three ways, roughly from best to worst:
Use a model’s pre-match xG if you trust one. Or take each side’s xG for and against over the last 10 to 15 games, home and away separately. Or, if you have nothing else, goals scored and conceded per game. The Poisson calculator has a mode that blends both teams’ averages with the league average for you.
A quick sense check: the two numbers usually add up to between 2.2 and 3.2. If yours come to 4.5, something’s off.
Most likely scores at 1.6 v 1.1
| Score | Chance | Fair odds |
|---|---|---|
| 1-1 | 11.8% | 8.45 |
| 1-0 | 10.8% | 9.30 |
| 2-1 | 9.5% | 10.57 |
| 2-0 | 8.6% | 11.62 |
| 0-1 | 7.4% | 13.53 |
| 0-0 | 6.7% | 14.88 |
| 1-2 | 6.5% | 15.37 |
Notice how flat it is. Even the favourite score lands less than one time in eight. That’s why correct score markets carry big margins: bookmakers often build in 20 to 30% across the whole market, so most prices you see are well under fair.
Backing more than one score
Tap cells on the CasinoCalcs grid and the calculator adds them up. 1-0, 2-0 and 2-1 together are 28.8%, fair odds 3.47. To back all three for the same return, stake each one in proportion to its chance: roughly 37%, 30% and 33% of your total here. The dutching calculator does the exact stakes once you have the bookmaker’s prices.
What the model gets wrong
It treats the two teams’ goals as independent. They aren’t quite. Low-scoring draws turn up a little more than the maths says, partly because a side that’s level late on often settles for it. If you’re looking at 0-0 or 1-1, shade the model’s price down a touch. It also knows nothing about injuries, weather or a team that’s already safe.
For goals markets rather than exact scores, see the BTTS calculator and the half time/full time calculator.
For over/under goals instead of exact scores, see the total goals calculator.
Correct score bets lose far more often than they win, even when the price is right. BeGambleAware.org is free and confidential if you need it.