Every price is a probability in disguise
A betting price is really a statement about how likely an outcome is. The implied probability is the win rate at which a bet at that price exactly breaks even over the long run. Below it, the bet loses money on average; above it, the bet makes money on average.
Reading prices as probabilities is the single most useful habit in sports betting analysis, because probabilities can be compared directly with a forecast. Prices, on their own, cannot.
The conversions
From decimal odds: implied probability = 1 ÷ decimal odds. Odds of 2.50 imply 40%.
From American minus odds: |odds| ÷ (|odds| + 100). −120 implies 120 ÷ 220 = 54.5%.
From American plus odds: 100 ÷ (odds + 100). +200 implies 100 ÷ 300 = 33.3%.
Why both sides add up to more than 100%
Take a game priced −110 on both sides. Each side implies 110 ÷ 210 = 52.38%. Together they add up to 104.76%, even though one of the two teams must win.
The extra 4.76% is the sportsbook's margin, often called the vig, juice or overround. It is how the book gets paid: whichever side wins, the prices were set so that the book is ahead across all its customers.
Removing the margin
To see what a market believes without the margin, divide each side's implied probability by the total. In the −110/−110 example, 52.38% ÷ 104.76% = 50% for each team. That is the no-vig, or fair, probability.
The same method works for three-way soccer markets: add the home, draw and away implied probabilities, then divide each one by the sum. The fair price guide walks through turning the result back into odds.
Comparing with a forecast
Once a price is a probability, you can put it next to a model's estimate. If a model gives an underdog 45% and the best price is +150 (implied 40%), the price pays as though the team wins less often than the model expects. That gap is what SharpDeck calls the edge, measured in percentage points.
A gap is not a guarantee of a win. It says the price and the forecast disagree, and the forecast's public track record is what tells you how much weight its side of the disagreement deserves.
SharpDeck field notes. Product explanations and worked examples, not betting recommendations.