BOSTON (AP) - If a stay-at-home mom could be compensated in dollars rather than personal satisfaction and unconditional love, she'd rake in a nifty sum of nearly $117,000 a year.

That's according to a pre-Mother's Day study released Thursday by Salary.com, a Waltham-based firm that studies workplace compensation.

This year's eighth annual survey calculates a mom's market value by studying pay levels for 10 job titles with duties that a typical mom performs, ranging from housekeeper and day care center teacher to van driver, psychologist and CEO.

This year's stay-at-home mom annual salary would be $116,805 per year, while a working mom who also juggles an outside job would get $68,405.

One stay-at-home mom says the nearly $117,000 figure sounds a little low.

"I think a lot of people think we sit and home and have a lot of fun and don't do a lot of work," said Samantha Russell, a Fremont, N.H. mother who left her job as pastry chef to raise two boys, aged 2 and 4. "But they should try cleaning their house with little kids running around and messing it up right after them."

Salary.com's 2008 stay-at-home mom figure is down from $138,094 last year, and the working mom calculation is below last year's $85,938 - declines primarily due to a change in study methodology.

Previous years' surveys calculated pay based on the national median base salary for companies of all sizes. But Salary.com adjusted its methods to account for the fact that the working mothers surveyed for this year's study were more likely than the average worker to be employed at a small company.

"Smaller organizations typically pay less," said Bill Coleman, a Salary.com vice president.

The biggest driver of moms' theoretical six-figure salary is the amount of overtime pay they'd be receiving for working more than 40 hours a week. The 18,000 moms surveyed about their typical week reported working 94.4 hours - meaning they'd be spending more than half their working hours on overtime.

Working moms reported an average 54.6 hour "mom work week" besides the hours they spent at paying jobs.

Russell agreed her job as a stay-at-home mom is more than full-time. But she said her "job" brings intangible benefits she wouldn't enjoy in the workplace.

"The rewards aren't monetary, but it's a reward knowing that they're safe and happy," Russell said. "It's worth it all."