Futures Fair Value Calculator

Sportsbooks build a margin (vig or juice) into futures markets by inflating implied probabilities beyond 100%. A typical futures market may sum to 120-140%, meaning 20-40% is overround the books keep as profit margin.

• A 130% total market implies ~30% overround (vig)
• Each outcome's probability is inflated proportionally
• Removing the vig reveals the true fair probability

Fair probability comes from converting each price to an implied probability and normalising the total back to 100%. That only removes vig if you have the WHOLE field. A book's complete market sums to more than 100%, and the excess is the margin. If your entries sum to less than 100% you are missing outcomes, and normalising up would inflate every one of them.

• Step 1: Convert each line to implied probability
• Step 2: Sum all implied probabilities (the overround)
• Step 3: Check the total is ABOVE 100%. Below means the field is incomplete
• Step 4: Divide each by the total to normalize to 100%
• Step 4: Convert back to odds for fair lines

The Kelly criterion sizes bets optimally based on your edge and odds. For futures with small edges, quarter-Kelly (25% of full Kelly) is recommended to reduce variance and account for estimation uncertainty.

• Full Kelly: f* = (bp - q) / b, where b = net odds, p = win prob, q = 1-p
• Quarter Kelly reduces bankroll volatility by ~75%
• Never bet negative edge outcomes regardless of conviction
• Futures are high-variance; conservative sizing is critical

Futures odds vary significantly across sportsbooks because each book forms independent opinions and manages different liability profiles. Shopping for the best line on your target outcome can add 1-5% of expected value.

• Enter odds from 2-4 books per entry to compare
• Even small odds differences create meaningful EV gaps
• Best practice: always have accounts at 3+ sportsbooks
• Line movement timing matters for capturing value