It's no secret that football is the real money maker in University of Michigan athletics.

But exactly how much revenue do the roughly 100 students and 20 coaches and staff in the program bring in?

$82 million.

Football accounted for at least 57 percent of athletic department revenues in 2012-13, which totaled $144 million, according to Michigan budget documents provided to the Board of Regents.

The storied program and its larger-than-life venue are what solidifies Michigan's place among the most profitable enterprises in college sports. Football cost about $23 million to operate in 2012-13, meaning it fed more than $58 million into Michigan's other 30 varsity teams.

The $82 million haul doesn't count indirect revenues, such as sponsorships, licensing and advertising agreements — which totaled $22.5 million that year — primarily made attractive by the football and basketball programs.

"It's extremely important," athletic director Dave Brandon said of the football program.

"All of the facilities and coaches and the infrastructure required to have 31 teams fundamentally all gets paid for by two programs: basketball and football," he continued. "Those revenues are the reason why we can have so many teams competing in so many activities and have a really broad-based program."

Department revenues rose $41.5 million from 2009-10 to 2012-13. During that same four-year period, expenses increased at a similar level, rising from $87 million to $132 million.

Much of the revenue uptick came from hikes in spectator fees — like required donations and tickets — and an increasingly profitable Big Ten conference. Meanwhile, the steep increase in costs can be pinned on staffing changes, inflation and a construction surge.

"Part of their growth has just been the growth in cost of running the place," said U-M President Mary Sue Coleman.

Ticket equation

Of the $43 million in ticket sales at Michigan during 2012-13, $37 million came from Michigan football's six home games.

That doesn't include the seat licenses season ticket holders must pay and the donations necessary for club seats and the 81 luxury boxes, which cost between $55,000 and $85,000 a season and have waiting lists of wealthy fans who want a premium spot.

The athletic department earned at least $27 million in priority seating and annual gifts in 2012-13, a number that began a stark rise after the renovated stadium opened in 2010. The year before the renovation, priority seating brought in just over $19 million.

Seat licenses, introduced by former athletic director Bill Martin in 2005, have become more costly, with the athletic department tacking $100 onto required donations that were already $500 and $250 a seat.

Ticket prices, too, increased. In 2010, student season ticket holders paid $28 per game and non-students with basic season tickets paid $54 per game. Students now pay $40 per game and non-students pay about $65 per game.

The introduction of dynamic pricing in 2013 — meaning fans who want tickets to individual games pay a price that varies based on supply and demand — was expected to infuse another million into Michigan's already-robust ticket sales.

And while fans have certainly grumbled about the uptick in price, Brandon says sales are as good as ever.

"We've been able to sell all of our seats with waiting lists," Brandon said. "Our ticket prices for football are still well below many of our benchmark competitors."

The prices of football tickets vary across the Big Ten. At Michigan State, season tickets average $44 per game, but at Ohio State season tickets average $79 per game.

Many fans, for their part, grumbled about the increases, in part because they had to absorb the hikes in a small period of time. Prior to Brandon becoming athletic director in 2010, Michigan hadn't raised prices for six years and seat licenses had remained flat since they were introduced.

He says prices won't rise next year.

"We try to be thoughtful about constant increases for our fans," he said. "Part of what got us so far behind is that it's hard to find anything that you go six years and you don't increase the price."

Numbers game

Fans don't just pay to sit in Michigan Stadium's more than 110,000 seats, they also buy plenty of food and merchandise while at the game: $1.8 million of the $3.6 million spent on spectator merchandise, game parking and concessions in 2012-13 was spent at the Big House over the course of six Saturdays.

Broadcast deals have sweetened conference incomes, and the the Big Ten, with the Big Ten Network, is one of the most profitable conferences in the NCAA. Over the course of four years, Michigan's Big Ten distributions rose by at least $8 million.

Of the $28 million Michigan received in NCAA conference distributions in 2012-13, $12 million was due to football and $8 million to basketball. Men's basketball is Michigan's other profitable sport: It brought in $15 million in 2012-13 and fed more than $8 million into other sports.

Meanwhile, U-M's 29 non-revenue sports brought in $8 million but incurred program-specific costs of $31 million. For example, women's basketball earns $440,000, but spends more than that on travel. In fact, it costs more than $3 million to run.

Expensive enterprise

Profitable NCAA Division I FBS League athletic departments often redirect surges in cashflow to facilities and, inevitably, to rising coach salaries and performance bonuses.

"There's a tremendous growth in athletic revenues for the [major college] programs," said Amy Perko, director of the Knight Commission on Intercollegiate Athletics. "History has shown that the influx of new revenues in athletics has been directed disproportionately to coaches' salaries and facilities."

In 2009-10, Michigan paid $33 million in wages to about 275 people. By 2012-13, the athletic department had 321 employees (it has grown even more this year to 336 workers) and projected $44 million in pay, including $19 million on coaches' salaries.

The top five earners at the athletic department in 2012 earned a combined $7 million in wages and benefits, with football coach Brady Hoke making $2.6 million, basketball coach John Beilein earning $2 million and Brandon earning $840,000, according to W-2 statements obtained by The Ann Arbor News.

At Michigan, it's not just the football and men's basketball coaches who are earning top dollar. Women's basketball coach Kim Arico earned $480,000 in 2012 and men's hockey coach Red Berenson earned $430,000 in 2012.

Thirteen of the top 30 earners at the athletic department coach or work in the football program.

Brandon says coaches are now more expensive then ever: "The pressure that's put on athletic departments is the fact that if you want to recruit and retain really, really good coaches who really do a good job in their sports, the amount of money that requires today verses 10 or 20 years ago is remarkably different."

Coaches aren't the only personnel line item that's growing — the athletic department as a whole is getting bulkier.

Over his tenure, Brandon has hired more marketers, sports administrators and even nutritionists than any athletic director before him. The department also absorbed new programs and their staff, including men's and women's lacrosse, dance and cheerleading.

Meanwhile, money spent on student athlete scholarships has increased nearly $3 million in four years, and is now more than $18 million.

Non-stop construction is another expense that's relatively new to the scene. The athletic department reopened Michigan Stadium in 2010 after a $226 million renovation, and since then the school has christened one renovated building after another.

"We’ve had to do a lot of renovations of the facilities, because our facilities in athletics had really become subpar," Coleman said in a recent interview. "What Dave has tried to do is create a plan to upgrade, and one of the things I like about his strategy and what he's tryng to do is not just to create better facilities for the revenue sports, but for the non-revenue sports. We want the best facilities for hockey. For women’s field hockey. We want it for swimming. We want it for rowing."

Crisler Center, Yost Field House, and Schembechler Hall have all been upgraded, and an indoor practice facility for football and a player development center for basketball were built from scratch. In all, Michigan has spent around $500 million in improving hockey, basketball and football facilities, and in the next five years it plans to spend another $250 million on Olympic sports.

As a result, Michigan's annual debt service has increased exponentially, from more than $2 million in the 2009-10 budget year to around $15 million last year.

When adjusting for inflation and not counting scholarships, Michigan's spending outpaces that of fellow Big Ten athletic departments. Michigan spent $122,500 per athlete in 2011, versus the Big Ten average of $109,500. That year it also spent nearly $16 million on coaching salaries, roughly $2 million more than its Big Ten peers, according to a Knight Commission database.

Heavy burden

In recent years, Michigan football's performance has been inconsistent. The team went 5-7 in 2009, 7-6 in 2010, 11-2 in 2011 and 8-5 in 2012. This past year, it went 7-6. Football underwent a rough, and very public, coaching transition, when the polarizing Rich Rodriguez was fired in 2010, after just three years in the job.

Yet whatever the football team's success on the field, the program, and the young athletes and highly paid coaches who make up its ranks, are faced with an enormous responsibility: being the financial cornerstone of an ever-growing athletic department.

Some worry that the burden on the football team is too heavy.

“It’s a house of cards," former U-M president James Duderstadt, who declined to be interviewed for this article, told NPR in December. "No matter how much you ‘build the brand,’ if you don’t have the product, sooner or later, it gets you.”

Brandon, however, notes that even in times of drought, fans have continued to flock to Michigan Stadium, which on fall Saturdays "becomes one of the largest cities in Michigan," and he thinks they always will.

Kellie Woodhouse covers higher education for the Ann Arbor News. Reach her at kelliewoodhouse@mlive.com or 734-255-5303 and follow her on twitter.