| Career - ERA | |||
| Rk | Player Name | Totals | |
| 1 | Raisel Iglesias | 2.90 | |
| 2 | Scott Downs | 2.99 | |
| 3 | Jose Fernandez | 3.22 | |
| 4 | Kevin Brown | 3.75 | |
| 5 | Kevin Appier | 3.81 | |
| 6 | Miguel Gonzalez | 3.82 | |
| 7 | Daniel Hudson | 3.89 | |
| 8 | Zane Smith | 3.90 | |
| 9 | Tim Wakefield | 3.99 | |
| 10 | Joaquin Benoit | 4.19 | |
| 11 | Logan Gilbert | 4.26 | |
| 12 | Zach Plesac | 4.26 | |
| 13 | Dave Stieb | 4.30 | |
| 14 | Josh Collmenter | 4.35 | |
| 15 | Jose Quintana | 4.60 | |
| 16 | Roy Oswalt | 4.66 | |
| 17 | Tim Lincecum | 4.71 | |
| 18 | Lance Lynn | 4.71 | |
| 19 | Blake Snell | 4.76 | |
| 20 | Roger Clemens | 4.82 | |
| 21 | Paul Abbott | 4.83 | |
| 22 | Jose Mesa | 5.03 | |
| 23 | A.J. Burnett | 5.03 | |
| 24 | Kevin Tapani | 5.11 | |
| 25 | Tyler Alexander | 5.23 | |
| Single Season - ERA | |||||
| Rk | Player Name | Totals | Year | ||
| 1 | Larry Andersen | 1.89 | 1992 | ||
| 2 | Jose Fernandez | 2.37 | 2014 | ||
| 3 | Kevin Brown | 2.43 | 1993 | ||
| 4 | Logan Gilbert | 2.43 | 2025 | ||
| 5 | Kevin Appier | 2.44 | 1993 | ||
| 6 | Spencer Strider | 2.49 | 2023 | ||
| 7 | Roger Clemens | 2.64 | 2006 | ||
| 8 | Dave Fleming | 2.67 | 1993 | ||
| 9 | Paul Abbott | 2.75 | 2000 | ||
| 10 | Kevin Appier | 2.88 | 1997 | ||
| 11 | Chris Devenski | 2.88 | 2017 | ||
| 12 | Miguel Gonzalez | 3.17 | 2013 | ||
| 13 | Kevin Appier | 3.19 | 1998 | ||
| 14 | Miguel Gonzalez | 3.19 | 2014 | ||
| 15 | Jose Fernandez | 3.20 | 2015 | ||
| 16 | Joaquin Benoit | 3.21 | 2006 | ||
| 17 | Daniel Hudson | 3.31 | 2011 | ||
| 18 | Jose Quintana | 3.34 | 2016 | ||
| 19 | Dave Stieb | 3.39 | 1992 | ||
| 20 | Tim Wakefield | 3.45 | 1996 | ||
| 21 | Kevin Appier | 3.50 | 1992 | ||
| 22 | Cody Anderson | 3.57 | 2016 | ||
| 23 | Chase De Jong | 3.57 | 2023 | ||
| 24 | Zach Plesac | 3.61 | 2021 | ||
| 25 | Roy Oswalt | 3.66 | 2011 | ||