Interactive Tools
Baseball Stat Calculators
A suite of interactive sabermetric calculators — type in the numbers and get an instant result, the exact formula used, and a one-line read on what it means. Everything runs in your browser; no data is fetched or fabricated. Where a weight or constant changes by season, you can edit it.
wOBA Calculator
Weighted On-Base Average from a hitter's events, using a representative recent-season weight set.
PitchingFIP Calculator
Fielding Independent Pitching from HR, BB, HBP, K and IP — with an editable, league-dependent FIP constant.
HittingBABIP Calculator
Batting Average on Balls In Play, to separate luck from skill and flag regression candidates.
HittingOPS & OPS+ Calculator
On-base plus slugging, and a league-relative OPS+ from the league OBP and SLG you supply (no park factor).
TeamPythagorean Win Expectation
Expected winning percentage and a projected W–L record from runs scored and runs allowed.
FlagshipPower Ranking Builder
Enter several teams' runs scored and allowed; get a live ranked table by Pythagorean wins and run differential, with a bar chart.
wOBA Calculator
Every way of reaching base carries the run value it has actually been worth, and the sum is divided by the plate appearances that could have produced one. Intentional walks come out of both halves because they are a manager’s decision, not a hitting skill. The weights shift a few points every season with the run environment; the set above is a representative recent-season one, and the calculator lets you replace it. Read the result on the on-base scale: about .320 is league average, .370 is very good, .400 is an MVP year.
Interactive tool
wOBA Calculator
Weighted On-Base Average from a hitter's events, using a representative recent-season weight set. This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
FIP Calculator
FIP keeps only the three outcomes a pitcher controls without his defense — home runs, walks and hit batters, strikeouts — and prices each at its run value. The constant is what puts the answer on the ERA scale, and it is league- and season-dependent; recent leagues run about 3.10, which is the default the tool uses and the field you can edit.
Interactive tool
FIP Calculator
Fielding Independent Pitching from HR, BB, HBP, K and IP — with an editable, league-dependent FIP constant. This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
BABIP Calculator
Batting average on balls that were actually fieldable. Home runs and strikeouts leave both halves because neither is ever in play. League BABIP sits near .290–.300; a hitter far above it is often due for regression, and for pitchers the gap between BABIP and .300 is mostly defense and luck rather than skill.
Interactive tool
BABIP Calculator
Batting Average on Balls In Play, to separate luck from skill and flag regression candidates. This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
OPS & OPS+ Calculator
OPS+ = 100 × ( OBP/lgOBP + SLG/lgSLG − 1 )
OPS adds two rates that share no denominator, which is statistically crude and practically useful. OPS+ rescales it so that 100 is the league you supply: enter the league OBP and SLG for the season you care about and the tool reports the hitter relative to it. Note the one honest difference from Baseball-Reference’s published OPS+: this version takes no park factor, so it is league-relative but not park-adjusted.
Interactive tool
OPS & OPS+ Calculator
On-base plus slugging, and a league-relative OPS+ from the league OBP and SLG you supply (no park factor). This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
Pythagorean Win Expectation
Bill James’s Pythagorean expectation: how often a team should win given how many runs it scores and allows. The 1.83 exponent is the modern best fit across recent seasons. A team far above its expectation has usually been winning close games, which is the part of a record that carries over least.
Interactive tool
Pythagorean Win Expectation
Expected winning percentage and a projected W–L record from runs scored and runs allowed. This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
Power Ranking Builder
Enter several clubs’ runs scored and allowed and the tool ranks them by Pythagorean win expectation rather than by record, with run differential alongside. It is the same formula as the calculator above, applied to a table instead of one team, which is how a power ranking stops being a matter of taste.
Interactive tool
Power Ranking Builder
Enter several teams' runs scored and allowed; get a live ranked table by Pythagorean wins and run differential, with a bar chart. This interactive calculator needs JavaScript. The formula it uses is printed on this page, so the method works without it.
Linear weights and the FIP constant are season-dependent; the defaults shown are representative recent-season values, labeled on each tool. For the published weights of a specific year, see the FanGraphs Library.