MLB / Tool Comparison
Best MLB Park Factor Tools in 2026
Five sources publish MLB park factors and all five are free to read. Baseball Savant is the source of truth: it is keyed to the venue, uses a rolling three year window, and splits by batter handedness and by whether the roof was open. FanGraphs is keyed to the team and to a single season, and its numbers are already halved so you can apply them directly to full season statistics. FantasyPros publishes a simple three season table. BallparkPal is the only one that produces a per game and per batter park number rather than a season figure. BankrollSZN ranks all 30 stadiums by home run factor with righty and lefty splits and layers first pitch weather on top. Checked August 2026.
| # | Source | Best for | Free? | Keyed to |
|---|---|---|---|---|
| 1 | Baseball Savant | Best source of truth | Yes, no signup | Venue, rolling three year |
| 2 | BallparkPal | Best per game and per batter park number | Yes, no signup | Venue, single game |
| 3 | BankrollSZN | Best for DFS lineup decisions, ranked with weather layered on | Yes, free account | Venue, handedness split |
| 4 | FanGraphs | Best for adjusting full season statistics | Yes, CSV export is paid | Team, single season, pre-halved |
| 5 | FantasyPros | Best simple three season table | Yes, no signup | Team, three season |
All five are free to read as of August 2026. Baseball Savant is the underlying data source for several of the others, including BankrollSZN.
The two numbers people confuse
Baseball Savant is keyed to the venue and uses a rolling multi season window, comparing how the same batters and pitchers performed in that park against how they performed everywhere else. FanGraphs is keyed to the team and to a single season, and its published factors are already halved so they can be applied straight to a player's full season line, which assumes roughly half his games were at home.
They are not interchangeable, and using one where the other belongs is the most common park factor mistake there is. Apply a FanGraphs figure as though it were a Savant figure and you have halved the effect twice. Check which convention a number follows before you multiply anything by it.
Why the handedness split is the part that matters
Outfields are not symmetric, so one park can be a good home run park for left-handed hitters and a poor one for right-handed hitters at the same time. The Green Monster and the short porch in right at Yankee Stadium are the obvious cases, but nearly every park has some version of this.
A single blended park factor averages the two splits together and hides exactly the information a lineup decision needs. If you are deciding whether to roster a specific hitter, the number you want is the one for his side of the plate. Savant and BankrollSZN both expose that split; a generic overall figure does not.
Season park factors versus today's park factor
A park factor is a slow moving baseline computed over multiple seasons, which is why a single season number early in the year is noisy and not worth reacting to. Real movement happens when a park changes its dimensions, moves its fences, or a team relocates, not from week to week.
Wind, temperature and air density are the fast moving layer that sits on top. A hitter friendly park with a stiff wind blowing in can play neutral or worse for one afternoon. BallparkPal is the only source listed here that folds the day's conditions into the park number itself. Everywhere else, including BankrollSZN, you check the park factor and the weather as two separate inputs.
Where BankrollSZN fits
BankrollSZN ranks all 30 MLB stadiums by home run factor with a right-handed and left-handed toggle and three seasons available, plus an individual profile page for every park with dimensions and full splits, plus a first pitch weather tool on the same site. It is free with a free account. Neutral site and temporary venues are excluded from the ranking so the comparison is like for like.
It is built on Baseball Savant's data rather than replacing it, which is the honest framing. If you want the raw leaderboard with every filter, go to Savant. If you want the same data ranked, split by handedness, linked to a per stadium page and sitting next to today's wind, that is what this site adds on top.
Frequently asked questions
What is the best free MLB park factor source?
Baseball Savant, if you want the underlying data. It is keyed to the venue, uses a rolling three year window, controls for the batters and pitchers involved, and splits by handedness and roof state, with no account required.
What is the difference between Baseball Savant and FanGraphs park factors?
Savant is keyed to the venue and uses a rolling multi season window. FanGraphs is keyed to the team and to one season, and its factors are already halved so they can be applied straight to full season statistics. Using one in place of the other gives you a wrong adjustment.
Do park factors change every year?
They move slowly because they are computed over several seasons. A single season figure early in the year is noisy. Meaningful shifts happen when a park changes its dimensions or a team moves.
Is Coors Field still the best hitters park?
Coors keeps an elevated run factor from altitude and large outfield gaps, which helps extra base hits more than it helps home runs specifically. It is not always the home run leader in a given season, so check the current year and the handedness split rather than assuming.
Should I use park factors or weather?
Both, in that order. The park factor is the baseline and the day's wind and temperature adjust it. A hitter friendly park with the wind blowing in can play neutral.