Reading implied probability from any price you are quoted

Every market you touch is quoting a probability, whether it says so or not. American odds, decimal odds, prediction-market cents and options premiums are all just different clothing on the same number.

For decimal odds, implied probability is one divided by the price. A decimal price of 1.91 implies roughly 52.4 percent. For American odds on a favourite, take the odds divided by the odds plus one hundred: minus 110 becomes 110 divided by 210, again 52.4 percent. For an underdog, use one hundred divided by the odds plus one hundred.

Prediction markets are the easiest of all: a contract trading at 61 cents implies a 61 percent chance, minus fees. Equities are the hardest, because price alone does not name an outcome. That is why a stock read has to be framed as a specific claim with a horizon, such as the probability of closing above a level within thirty days.

Once every quote is a percentage, comparison becomes trivial. You can rank an NBA spread, a Bitcoin level and an election contract on the same scale and put your money where the gap is widest.

One caveat: the raw implied probabilities across all outcomes in a market sum to more than one hundred percent. That excess is the vig. Strip it proportionally before you compare, or you will systematically overstate your edge.