Type two MLB team names into the boxes below (start typing and pick from the suggestions), choose which one is the home team, and press Calculate true odds.

You'll get each team's estimated chance of winning, the "fair" decimal odds and moneyline that chance implies, and their past head-to-head results this season and last.

If you've got odds from a sportsbook for the same game, pop them into the two boxes at the bottom of the results to see whether the price looks generous or stingy compared to this model.

The leaderboard further down shows current Elo ratings for all 30 teams, based on results through 20261004.

ESPN button (recommended for weekly updates): pulls simple win/loss/score  data straight from ESPN's live scoreboard, day by day, from wherever this model currently leaves off through today. Works any time during the season, including mid-season, and can be re-run weekly to keep the model current. It isn't Retrosheet-verified box-score data, but for "who won and by how much" it's reliable — that's genuinely all the model needs. Retrosheet button: fetches the current season's official gamelog directly from the chadwickbureau/retrosheet GitHub mirror. Retrosheet only publishes this file after a season concludes and is fully processed, so this button will report nothing available until then — that's expected, not a bug. Download the current-season gamelog file from Retrosheet (or the chadwickbureau/retrosheet GitHub mirror) — a file named like GL2026.TXT — and drop it in here. This is the standard Retrosheet gamelog format: no header row, quoted comma-separated fields, with date in column 1, visiting team in column 4, home team in column 7, visitor runs in column 10, and home runs in column 11. New games merge in and duplicates are skipped automatically — ratings recalculate instantly in your browser. Nothing is uploaded anywhere; it's all processed locally on this page. Once you've merged new data, use your browser's Save Page As (Ctrl/Cmd+S) and choose "Webpage, HTML only" to save it as a new file with the update baked in — otherwise it's only good for this browser session and reverts to the built-in data on reopen.

Adding starters layers a pitching-matchup adjustment on top of team Elo, based on each pitcher's rolling runs-allowed rate (not simple win/loss — see footer for why). Leave blank to treat a side as an average starter.