Methodology

Last updated: Oct 27, 2026

This page sets out the rules OddsFantasy's pre-match positive EV and arbitrage feeds use to decide what to list, and what trading through the terminal costs. They are the rules the feeds run today; the date above shows when the page was last checked against them.

Fair odds: Pinnacle's no-vig line

Every pre-match value bet is priced against Pinnacle. Pinnacle's odds become fair odds once its margin is removed: with the power method when the market has a clear favourite, and the multiplicative method otherwise.

A Pinnacle market with a margin above 8% is not used.
A Pinnacle line with a limit under $25 is not used.
A Pinnacle market where any outcome is priced below 1.20 is not used.
Pinnacle's American football team totals are not used.

Reference freshness: 20 minutes

A Pinnacle price older than 20 minutes is not used, so no value bet is listed from it.

The age is measured from when Pinnacle produced the price, not from when OddsFantasy read it. Pinnacle's public odds are served through a cache, so the cache's own age is taken off the time of each read.

When a price is a value bet

A bookmaker's price is compared with the fair odds for the same outcome:

EV = bookmaker odds ÷ fair odds − 1

The bookmaker's price must have been read in the last 30 minutes.
At least 3 other bookmakers, each read in the last 30 minutes, must price the same outcome at or below the fair odds, and no more than 1 may price it above them.
EV divided by the standard deviation of the bet's return must be at least 1.25%, plus 0.1 points for each point of Pinnacle's margin.
EV above 15% is not listed: a gap that large is almost always a wrong match or a stale price.
Odds above 5.0 are not listed.
Only games starting in the next 7 days are scanned.

Fees come off before prices are compared

Prediction-market and exchange prices are turned into odds after their fees, so a value bet or arb that only exists before fees is never listed.

Polymarket: odds = 1 ÷ (price + taker fee per share), using each market's own fee schedule (0.05 × p × (1 − p) on most sports markets; some markets, such as NBA games, have no fee). The price is the live best ask in the order book when the bet is saved.
Kalshi: odds = 1 ÷ (price + 0.07 × m × P × (1 − P)), where m is the series' fee multiplier.
Betting exchanges: odds = 1 + (odds − 1) × (1 − commission).
OddsFantasy's own builder fee, below, is not taken off the EV shown.

Arbitrage

Every leg's odds are net of fees and commission, as above. It is an arb only when the legs' implied probabilities add up to less than 100%; combinations under 85% are dropped as data errors.
Both bookmakers' prices must have been read in the last 30 minutes.
Each bookmaker's no-vig view of the market must sit within 7 percentage points of Pinnacle's, or of the next reference bookmaker's where Pinnacle has no such market. Otherwise the arb is dropped as a wrong match or market.
If either bookmaker's full-game money line is more than 10 points from the reference, all of that pair's arbs on the game are dropped.
More than 5 arbs between two bookmakers on one match is treated as a matching error, and none of them are listed.

Trading fees in the terminal

The terminal is free to use without a plan. Every order placed through it, by hand or by automation, carries OddsFantasy's Polymarket builder code, so each fill pays:

Fill	OddsFantasy builder fee	Polymarket fee
Taker (matches at once)	1% of the amount traded	Fee rate × p × (1 − p) per share; 0.05 on most sports markets
Maker (resting limit order filled later)	0.5% of the amount traded	None

Take-profit and stop-loss exits always fill as takers. The trade ticket's profit and loss figures include both fees.

Checking the builder fee

Polymarket publishes the rates for OddsFantasy's builder code on its own API, in basis points (100 = 1%):

https://clob.polymarket.com/fees/builder-fees/0x733a825536dd20aadb4b5ae8ed19641ad19360edb257620abec4ac8152b6e47b

Methodology FAQs

How fresh is the Pinnacle line behind a value bet?

No more than 20 minutes old, measured from when Pinnacle produced the price rather than when OddsFantasy read it. The bookmaker's own price, and the prices of the 3 books that confirm it, must have been read in the last 30 minutes.

Does the EV shown include fees?

It includes Polymarket's and Kalshi's taker fees and exchange commission. It does not include OddsFantasy's builder fee on terminal orders: 1% on taker fills and 0.5% on maker fills.

Does OddsFantasy charge a fee on trades?

Yes. Orders placed through the terminal pay a builder fee of 1% of the amount traded on taker fills and 0.5% on maker fills, on top of Polymarket's own fee. Using the terminal needs no plan.