Odds methodology

Where prices come from

Licensed data providers deliver prices to our servers on a schedule. Our pages never contact a sportsbook or a data provider while you load them. We store every price change, which gives us opening lines, price history and closing odds.

Each market is mapped to one standard name (for example moneyline, spread, total or both teams to score), and each game is checked to be the same event at every source before we show its prices.

Average market odds

The market average for an outcome is the median of all prices we hold for it. Unlike a simple mean, the median ignores a single stale or promotional price.

Example: a soccer match priced at 2.10 for a home win, 3.40 for a draw and 3.50 for an away win, in decimal odds. We use these prices in every example below.

Payout and the vig

payout = 100% ÷ (1/price₁ + 1/price₂ + …)

In the example the inverse prices add up to 105.6%, so the payout is 94.7% and the margin (the vig, or hold) 5.6%. A payout of 95% means that on average $95 of every $100 bet on the market is paid back; the rest is the sportsbook's margin. Higher payout is better for you.

Fair (no-vig) probabilities

A price implies a probability of 1 ÷ price: 47.6%, 29.4% and 28.6% in the example. Because of the vig these add up to more than 100%. We remove the vig by dividing each implied probability by their sum (the multiplicative method), which gives fair probabilities of 45.1%, 27.9% and 27.1%.

These fair probabilities are what our 'who will win' bar shows. They are calculated from every sportsbook we receive, including low-margin books and exchanges that we never display, because their prices are the most accurate guide to the true probabilities.

Best price and order

A price is marked best when it is the highest available for that outcome among the sportsbooks shown to you; ties are all marked. Best prices are shown in bold with a tint and the label 'best', never by color alone.

In each state we show prices from up to three licensed sportsbooks whose odds we receive, then the other licensed sportsbooks as logos. Which sportsbooks appear is decided by licenses where you are. No sportsbook can pay for its position. Where prediction markets may be shown, their prices appear in a separate row: a 60¢ contract means a 60% implied probability.

Poland's stake tax

This applies to visitors in Poland only. There 12% of every stake is tax, and bookmakers pass it on to players: of a 100 zł stake, 88 zł is in play. For visitors in Poland we therefore show prices after tax (price × 0.88) by default and label them. Wins above PLN 2,280 are also taxed at 10% of the whole amount. Our bet calculator includes both.

Line movement

The opening line is the first price we recorded for an outcome; movement arrows compare a price with its previous value.

For line movement we take, for each outcome, the median price at the start of the time window and the median price now, across the sportsbooks that priced it at both moments, and show what share of those sportsbooks shortened their price by at least 1%.

Closing odds

The closing price (the closing line) is a sportsbook's last price before the game starts. We keep closing prices permanently: they are the best measure of how the market rated a game, and they are what we show for finished games and in head-to-head records.

How fresh the prices are

Pregame prices are refreshed within minutes, and the comparison on a game page is never more than a few seconds behind our database. Prices can still change at the sportsbook before you place a bet, so always check the price in the sportsbook's own app or site.