What determines a boxing purse?

It all depends on the contract if their is one. For the big fights, it's a mixture of PPV/Ticket sales and a guaranteed fee that is usually paid out by the venue and promotions once the fight is over. If the fighters aren't guaranteed a certain split in pay, the fighter who wins usually gets a larger percentage of pay. People like Don king promote the fights and based on past sales and revenue from the other fights make a determination on the amount that either will be under contract or will go to the winner and loser.

Ex: main event

1) Attendance revenue = 30 million

2) Promoters and sponsers = 35 million

3) PPV or HBO = 35 million

-------------------------------------

Grand total = 100 million

SPLIT:

Boxer One: 31 million

Boxer Two: 25 million ( underdog)

or

Winner: 30 million

Loser: 20 million

Ref= 1 million

Commentators= 7 million

Don King = 15 million

etc...

-- Everyone gets paid based off of this number. I bet PPV does an average to come up with a lowest and highest number of viewers and makes a determination on that as to owhat they are willing to pay out for the right to show the fight exclusively on cable.