Methodology

This page explains where Linewhale's numbers come from and exactly how each one is calculated, so you can judge how far to trust them. For who we are, see the About page.

Where the odds come from

Linewhale pulls prices from an odds data provider that aggregates 100+ sportsbooks and prediction-market exchanges across 8 regions: the US, UK, Europe, Australia, Canada, France, Sweden, and Finland. We collect three markets for each event: moneyline (head to head), point spread, and game total (over/under). Covered leagues are NFL, NCAAF, NBA, NCAAB, MLB, NHL, MMA, MLS, and EPL.

We don't take bets and we don't set prices. Every number is a sportsbook's own posted price, and every price links back to that sportsbook.

How often it updates

Each sport is refreshed about once a minute while it has an upcoming or live event. Whenever a book's price or line changes, the new value is saved and the old one is kept in that event's line history, which is what the line movement charts show.

If a book stops quoting a market, its last price is marked stale and left out of every comparison and calculation below, so a price that is no longer available doesn't show up as the best one. Updates arrive roughly a minute apart, so a price can occasionally be out of date by the time you click through. Always confirm the price at the sportsbook before betting.

Best price

For each outcome, the best price is the one with the highest payout (the highest decimal odds) among the sportsbooks currently quoting it. For spreads and totals we compare prices at the same line. A -3.5 price is never compared with a -4.5 price.

Removing the vig and the consensus fair probability

Odds include the sportsbook's margin (the vig). To estimate what a market implies without it, we do this for every sportsbook that quotes all outcomes of the same market:

1. Convert each outcome's price to an implied probability (1 divided by the decimal odds).
2. Add the implied probabilities for all outcomes. The total is above 100%, and the excess is that book's vig.
3. Divide each implied probability by that total so they sum to 100%.

The consensus fair probability for an outcome is the simple average of those no-vig probabilities across all books, and it is only calculated when at least two books quote the market. This is the win probability shown on event pages and the benchmark for the Positive EV Finder.

It is an estimate of what the betting market collectively implies, not a prediction of who will win, and it is only as good as the prices feeding it.

Positive EV

For every price at every sportsbook, expected value is (fair probability × decimal odds − 1) × 100, in percent. A value of +3% means that, if the consensus is right, each $100 bet at that price returns $3 on average over many bets. The Positive EV Finder shows prices with an EV of 2% or more, calculated only for exactly matching contracts (the same market and the same spread or total line). A positive EV bet can still lose, and EV depends on the consensus being accurate.

Arbitrage

An arbitrage exists when the best prices for all outcomes of the same market, taken at different sportsbooks, have implied probabilities that sum to less than 100%. The profit is (1 ÷ sum of implied probabilities − 1) × 100, and opportunities below 0.1% are ignored. The Arbitrage Finder lists them live, and the Arbitrage Calculator splits the stakes. Prices can change or be limited before you place both legs.

Middles

A middle is two bets on opposite sides of the same spread or total at different numbers, for example over 47.5 at one book and under 49.5 at another, so that both can win if the final result lands in between. The Middle Finder lists pairs with a window of at least half a point, sorted by window size.

Steam moves

A steam move is a sharp, fast price change at a sportsbook. On Linewhale it is a moneyline price whose implied probability changed by at least 5 percentage points (adjustable) compared with its price earlier in the selected window, 24 hours by default. We use moneyline only, because the data provider returns just a few alternate lines per book for spreads and totals, which would make a change in line look like a price move. Prices longer than -1000 at either end are excluded because tiny absolute changes there look large in probability terms. See the Steam Moves page.

Sportsbook rankings

The sportsbook rankings are recalculated monthly from recorded odds, using only prices posted before an event started so in-play pricing doesn't distort them. Each book gets a 0 to 100 composite score from how often it had the best price (35%), its average vig (30%), how often it moves first when the market moves (20%), and its market coverage (15%). No sportsbook pays to be ranked. Books with fewer than 10 events in a month are flagged as limited data.

Known limits

• Prices are about a minute old at best, and sportsbooks can change or limit a price at any time.
• Spread and total coverage is limited to the lines the data provider returns, so a book may offer more alternate lines than we show.
• The consensus fair probability is an estimate. Thinly quoted markets (few books) are less reliable.
• Linewhale may earn a commission when you sign up through a sportsbook link. This never changes which prices we show or how we rank them.
• Nothing here is betting or financial advice.