Consensus Odds — Fair and Book Calculations

"Lines"

• "Line" here means the spread or over/under value associated with a set of odds.
• For bet types without a line (head to head, yes/no) every price is treated as having a line of 0.
• Both sides of a bet carry mirrored line values: home +3 ↔ away −3; over 165.5 ↔ under 165.5.

Fair odds

Key fields

• fairSpread or fairOverUnder: the fairest line (if applicable)
• fairOdds: the fair price for the given side at that line
• fairOddsAvailable: whether sufficient sharp data existed to calculate them

Summary

The fair price is derived from the exchange and sharp-book prices in the feed — the Betfair Exchange, Pinnacle, ProphetX, and Kalshi and Polymarket where they price the fixture — with the margin removed so the implied probabilities of the sides sum to one. It is never estimated from soft-book prices alone: where the sharp sources do not price a market, fairOdds is null and fairOddsAvailable is false. On the Lite plan fair fields are always null.

Calculation process

1. Group odds for each event + oddID by bookmakerID + line.
2. Keep the sharp sources (exchanges, Pinnacle, prediction markets) that are currently open for the market.
3. Choose the fair line: the line where the sharp sources' two sides are closest to balanced.
4. Take the consensus across those sources at that line.
5. Remove the juice: convert each side to implied probability, normalise so they sum to one, convert back to American.

Book odds

Key fields

• bookSpread or bookOverUnder: consensus main line across bookmakers
• bookOdds: consensus price for that line
• bookOddsAvailable: whether the side is open at at least one bookmaker

Summary

We identify each bookmaker's main line, select the most common main line across all bookmakers, and take the median price across bookmakers for that line.

Full calculation process

1. Group odds for each event + oddID by bookmakerID + line.
2. Identify the main line for each book; where a book doesn't distinguish main from alt, the line closest to the other books' main line is used.
3. Take the latest price from each group.
4. Combine, preferring prices that are open for betting.
5. Select the consensus book line: the line most books call their main line; ties go to the line closest to the fair line.
6. Consensus book odds = the median price across bookmakers for that line.