He won the Heisman Trophy and was given college football's best nickname, "Johnny Football," all before he could legally drink. Now Johnny Manziel is going pro, and with the Joe Montana and Joe Namath comparisons being thrown around like bad-hair jokes at a Donald Trump roast, many are excited about the quarterback's future.

Manziel is all but guaranteed to become a millionaire on NFL Draft Day, so the obvious question becomes: How many millions will he make?

The contract
The answer comes in many parts, beginning with the contract. Almost every analyst expects Manziel to be drafted in the first round, and he'll likely be taken off the board sooner rather than later. If he goes within the top 10 picks, his rookie deal should be worth between $12 million and $22 million over four years.

Since the NFL's rookie wage scale was introduced in 2011, six QBs have been drafted in the first 10 picks.

QBTeamOverall pick # (Year)Contract*
 
Signing Bonus
Andrew Luck Indianapolis 1 (2012) $22.1M, 4 years $14.5M
Robert Griffin III Washington 2 (2012) $21.1M, 4 years $13.8M
Ryan Tannehill Miami 8 (2012) $12.7M, 4 years $7.6M
Cam Newton Carolina 1 (2011) $22.0M, 4 years $14.5M
Jake Locker Tennessee 8 (2011) $12.0M, 4 years $7.6M
Blaine Gabbert Jacksonville 10 (2011) $12.0M, 4 years $7.2M

Sources: NFL and Spotrac. *Not included is one footnote of the rookie wage scale, which gives all teams the option to extend their first-round picks for a fifth year. As Bleacher Report explains, this decision must be made "after the third year of [a player's] contract, but before the start of his fourth season," and any top 10 pick is paid "the average of the salaries of the top 10 players in the league at his position," about $17 million by the author's calculations.

Recent history suggests that if Manziel is a top-10 pick, he could expect upwards of $5 million a year, plus a signing bonus of about $3.5 million. The Cleveland Browns, who hold the fourth pick, are reportedly "very high" on Manziel, according to CBS Sports. He could also go to the Jacksonville Jaguars at No. 3 or the Tampa Bay Buccaneers at No. 7 if Cleveland decides pass.

All of this, of course, is speculation. The sheer quantity of teams in need of a QB, though, means Manziel is unlikely to fall outside of the draft's top 10. In a best-case scenario, the total value of his contract could surpass $50 million if his fifth-year option is exercised come 2017. 

The endorsements
For a player as meteoric as Manziel, endorsements will be a major part of his fortune. The Associated Press reported earlier this week that Manziel confirmed the rumors: he'd chosen marketing firm LRMR to manage his sponsorships.

LRMR was co-founded by LeBron James and a group including Maverick Carter, who Forbes says has "solidified relationships" with McDonald's (MCD -0.05%)Nike (NKE 0.66%)Coca-Cola (KO 1.50%) and State Farm. Manziel and LeBron have publicly acknowledged their friendship.

Image via jmanziel2, Instagram. March 31, 2013.

James' endorsements with these companies and a few others earn him more than $40 million annually. 

The highest paid NFL star, in terms of sponsorship dollars, is Peyton Manning, who makes an estimated $12 million to $15 million per year. Of the six recently drafted QBs listed above, though, the most marketable are Robert Griffin III and Cam Newton. Both make between $2 million and $3 million in endorsements annually, according to Bleacher Report.

It should be no problem for Manziel to match these two, if not exceed them. From his friendship with rapper Drake to his relationship with LeBron, Manziel's celebrity is already more developed than most of his NFL peers. Endorsement deals that pay him something like $8 million a year -- a middle ground between Manning, Griffin, and Newton -- aren't out of the question.

The future
With nearly four months until the draft, a lot could change. If the injury bug strikes Manziel or he has a poor combine, there's a chance NFL squads could sour on him. Those odds remain very slim, however, and it's also possible Manziel could vault to the No. 1 pick. Somewhat more likely is further public relations trouble, which could hamper his appeal as an endorser. He's already experienced more than his share of negative notoriety, including a half-game suspension for "inadvertently violating" NCAA rules about receiving money for autographs, an arrest over a late-night fight, and an early departure from the Manning Passing Academy after oversleeping. If he avoids scandal going forward, businesses will have no problem chalking that up to youthful exuberance.

Barring a catastrophe, "Johnny Football" can make close to $50 million in salary his first five years in the league, and endorsement dollars can come close to matching this figure. If LRMR can establish Manziel as a Manning-esque persona, it's plausible he could make even more off the field.

A total take north of $90 million by 2019 remains a possibility, particularly if he leads a team like the Browns or Jaguars back to NFL relevance.