I've been looking for one good xBABIP calculator. The best I've found so far was slash12's which was posted on this site. I decided to test it and make my own xBABIP. The tests are from 2002-2011.

My formula is 0.025278+0.238105957967707*GB%+FB%*0.257892+LD%*0.365655+IFFB%*-0.37291+IFH%*0.372909+

0.04929*HR/FB

The formula was found using regression. I did some tests to find out which was better. Mine or slash12's.

So here is against future performance

Mine

Correlation

.388
RMSE

.0288

MAE

.022

Slash 12's

Correlation

.352

RMSE

.0343

MAE

.027

Against same season

Mine

correlation

.57

RMSE

.026

MAE

.021

Slash12's

Correlation

.49

RMSE

.027

MAE

.021.

So mine beats slash 12's in every test, same season, and next season. I made a google doc of my xBABIP calculator . You can get it here. IN the calculator only enter numbers in the green boxes.

EDIT: I made the calculator even better with some help from MJww. The correlation to next year is better at .44. The link and the formula have been updated in the post. The other tests are probably even better too. But I can't do them again for a reason that I messed up the spreadsheet I did them in and couldn't do slash12's because I didn't include the fangraphs batted ball% numbers.