From odds to win chance: how the win column on a UFC DFS sheet is made

Converting odds to a chance

For American odds, a favourite at −200 implies 200 / (200 + 100) = 66.7%. An underdog at +170 implies 100 / (170 + 100) = 37.0%. Those two add up to 103.7%. The extra 3.7% is the margin built into the prices.

To remove it, divide each implied chance by the total: 66.7 / 103.7 = 64.3% and 37.0 / 103.7 = 35.7%. These fictional numbers now add to 100% and describe the market's view of the fight.

From win chance to a projection

A projection is an expected score: the win chance times the points if they win, plus the loss chance times the points if they lose. A fictional fighter at 64% to win, with 95 points in a win and 25 in a loss, projects to 0.64 × 95 + 0.36 × 25 = 69.8 points.

The win chance moves the projection a lot, which is why it is the first column on the sheet. Call it lets you set your own win chance for any fighter and see the projection change.

What the win chance does not tell you

A win chance says nothing about how the win comes. Two fighters at 64% can have very different scoring profiles. Read the finish columns and the points if they win next to it.

The market's view also moves during fight week. DraftKings salaries are usually set before those moves, which is one reason prices and chances can drift apart by Saturday.

Decimal and fractional odds

Decimal odds convert directly: the implied chance is 1 divided by the odds. Decimal 1.50 implies 66.7%, and decimal 2.70 implies 37.0%. Fractional odds work the same way: 1/2 implies 2 / (1 + 2) = 66.7%, and 17/10 implies 10 / (17 + 10) = 37.0%. Whatever the format, the two sides of a fight still add up to more than 100% until the margin is removed.

Removing the margin is an approximation

Dividing each side by the total, as in the example above, spreads the margin in proportion to each price. It is the simplest method and the one most readers use. Other methods spread the margin differently, and they can move a heavy underdog's chance by a point or two. For DFS purposes the differences are usually small next to the uncertainty in the fight itself, but they explain why two sources can show slightly different win chances for the same fight.

What about draws?

Most two-way fight prices ignore draws, which are rare in MMA. A draw earns no DraftKings win bonus for either fighter. For projections, treating a fight as two outcomes is usually close enough, with the small draw chance folded into the loss side of the calculation.

Using the win chance well

Treat the fair win chance as the backbone of a projection, then layer the finish split on top. If you disagree with the market about a fight, put your own number into Call it and see what it does to the projection, the 100+ chance and the leverage. Writing the reason down is what makes the disagreement reviewable on Monday.

Common questions