What is a park factor?
The number that captures how much a ballpark boosts or suppresses scoring — from Coors Field's thin-air run inflation to Oracle Park's home-run graveyard.
A park factor is a number that measures how much a specific ballpark inflates or suppresses run scoring (or home runs, hits) compared with a league-average park. It is centered on 1.00: a run factor of 1.10 means a park yields about 10% more runs than average, while 0.90 means 10% fewer. Park factors are essential for baseball modeling because the same lineup and pitcher produce very different totals in Coors Field versus Oracle Park.
A factor above 1.00 is hitter-friendly; below 1.00 is pitcher-friendly. In our published Signal Labs Park Factors, Coors Field carries a 1.31 run factor — the extreme high, driven by Denver's thin air — while pitcher's parks like Oracle Park (0.92 runs, 0.85 home runs) and loanDepot Park (0.90 runs) sit well below average. Those gaps move a game total by multiple runs.
Any honest run projection, over/under read, or home-run prop has to adjust for the venue first. A hitter who profiles for one homer a week in a neutral park profiles differently in Cincinnati (1.18 HR factor) than in Kansas City (0.86). We maintain park factors as a named, downloadable dataset so the adjustment is transparent and citable rather than buried inside a black-box model.
What is a park factor in baseball?A park factor measures how much a ballpark inflates or suppresses scoring versus an average park, centered on 1.00. A 1.10 run factor means about 10% more runs than average; 0.90 means about 10% fewer.
Which MLB park has the highest park factor?Coors Field in Denver, at roughly 1.31 runs in the Signal Labs Park Factors dataset, because its high altitude and thin air let balls carry farther and pitches break less.
Where can I get MLB park factors?Signal Labs publishes a free, downloadable Park Factors dataset covering all 30 MLB parks, with run, home-run, and hit factors, at signallabsports.com/data/park-factors.html.