Robert F. McDonnell on the day of his conviction. (Marvin Joseph/The Washington Post)

Former Virginia governor Robert F. McDonnell will likely lose about $3,700 a month in pension payments as a result of his conviction last year on corruption charges, according to the formula the state uses to calculate benefits.

Gov. Terry McAuliffe (D) last week started the process of stripping his predecessor of his pension after Attorney General Mark R. Herring (D) released a legal opinion saying McDonnell was no longer entitled to the payments. Herring ruled that under a law McDonnell signed in 2011, state employees convicted of felonies related to on-the-job conduct must relinquish their benefits.

It is not clear exactly how much of a financial loss that will be for McDonnell, 61, who was convicted on 11 corruption-related counts stemming from his dealings with a Richmond businessman.

Individual pension benefits are not public. But the formula used to calculate them is. Virginia state employees all receive the same benefit package, regardless of position. Those benefits are calculated based on employees’ age, years in the public sector and their highest-paid three years of service.

“The governor is treated just like I am as a state employee,” said Jeanne Chenault, spokeswoman for the Virginia Retirement System.

Before becoming governor, McDonnell served for 3 1/2 years as attorney general, 14 years in the Virginia House of Delegates and two years as an assistant prosecutor. That gives him about 23 1/2 years of public service in the VRS system.

Given his age, his years of public service and the $175,000 salary that he was paid as governor, McDonnell’s benefits most likely come to about $3,700 a month, or $44,400 a year.

His benefits would be based on his salary as governor, his highest-paying job. The policy of calculating benefits that way is controversial because it means that state lawmakers — who work part time and are paid $17,640 to $18,000 a year — can dramatically increase their pensions by taking higher-paying state jobs toward the end of their careers.

The standard retirement age for public employees in Virginia is 65. Workers who retire at 65 — or after 30 years of service — receive the maximum pension. McDonnell left office at age 58, with about 23 1/2 years of working for the state.

The former governor may also receive benefits from the military. McDonnell was an Army medical supply officer for four years, serving mostly in Germany, and spent 17 years in the Army Reserve. The opinion issued by Herring last week did not address whether McDonnell’s conviction would imperil any military pension he receives.

McDonnell is appealing his conviction. He has not begun serving his two-year prison sentence.

The former governor also plans to challenge the pension revocation. His attorney on that issue, former state attorney general Anthony F. “Tony” Troy, said it was “unfair” to take away pension benefits that accrued before the 2011 law.