How to Read Football Prediction Probabilities
What an estimated probability like 55% actually means, how it relates to bookmaker odds, and why a good forecast can still lose.
By GoalPredicts Editorial Team · Reviewed
A probability is a long-run frequency, not a promise
When a prediction says a home win has an estimated probability of 55%, it means that if you could replay the same match under the same conditions many times, the model expects the home side to win a little more than half of them. It also means the model expects the home side not to win in roughly 45 of every 100 such replays.
That second half matters. A 55% outcome failing to happen is not a sign that the forecast was wrong. It is exactly what a 55% estimate says will happen quite often. Judging a single prediction by whether it won or lost tells you very little; judging hundreds of them together tells you much more.
Converting between odds and probabilities
Decimal odds can be turned into an implied probability by dividing 1 by the odds. Odds of 2.00 imply 50%, odds of 1.80 imply about 55.6%, and odds of 3.50 imply about 28.6%.
If you add up the implied probabilities of every outcome in a bookmaker's market, the total is usually more than 100%. The excess is the bookmaker's margin (often called the overround). To compare a bookmaker's view with a model's view fairly, people often scale the implied probabilities so they add up to 100% first.
A model's probability being higher than a bookmaker's implied probability does not mean a bet is guaranteed to be profitable. Both are estimates, and both can be wrong.
What makes a probability trustworthy: calibration
A forecaster is well calibrated when its probabilities match what actually happens over time. Of all the outcomes it rated at about 60%, roughly 60% should occur; of those it rated at about 30%, roughly 30% should occur.
Calibration can only be checked over a large number of predictions, ideally hundreds or more. A short run of wins or losses says almost nothing about calibration, because random variation dominates small samples.
How GoalPredicts presents probabilities
Every GoalPredicts prediction shows the selection together with its estimated probability, and the detail page shows the probability of every outcome in that market. We don't attach labels such as 'banker' or 'sure thing', because no football outcome is certain.
Our results page lists every settled prediction, including losses and voids, so the record can be judged as a whole rather than by its best moments.