According to one new report, $138,095 a year.
That's the figure in a report by Salary.com, which calculates the wages that would have been paid a stay-at-home mom in 2007 if she were compensated for all the elements of her "job." That total is up 3% from 2006's salary of $134,121.
Moms who have jobs outside the house would earn another $85,939 for their mothering work, beyond what they bring home in existing salary.
The job descriptions that Salary.com used to determine a mom's salary includes 10 jobs that moms do on an average day: housekeeper, day care center teacher, cook, computer operator, laundry machine operator, janitor, facilities manager, van driver, CEO and psychologist.
Plenty of overtime
In calculating a mom's wages, Salary.com looked at the "overtime" that both working and stay-at-home moms put in each week.
"Mom works multiple jobs and rarely gets a break from the action, working an average of 52 hours of overtime," said Bill Coleman, senior vice president at Salary.com, in a statement.
According to the Salary.com survey, stay-at-home moms work a 92-hour week, with more than half the workweek spent in overtime.
Working moms, meanwhile, logged more than nine hours of "overtime," with an average 49-hour "mom" work week -- on top of their full-time paying jobs.
For the Salary.com survey, more than 40,000 moms quantified their hours per job description; Salary.com benchmarked the median salaries for each job to the national median salary for each position as reported by employers.
The final salary was calculated by weighting the salaries and hours worked in each role.
And Bernie The Window Cleaner.