ABC News’ Lauren Effron and Dan Lieberman report:

Often in the fashion industry, modeling goes way beyond looks. It’s all about the numbers: age, height, weight, commission  — factors that determine whether one can become a top model, or any model at all.  These details are included in every photo shoot, television commercial and runway walk.

Dollars and Sense

Last year, professional “everyday” models employed by an agency made on average $42,560 a year, with an average hourly wage of $20.46, according to the Bureau of Labor Statistics. However, about 18 percent of models are self-employed or take  free-lance  freelance, part-time assignemts, so the range can vary.

Obviously, the world’s top supermodels  pull in much grander salaries. Forbes reported that the top three highest paid models included supermodel Gisele Bundchen, 29, who raked in $25 million last year, followed by “Project Runway” host Heidi Klum, 38, with $16 million in earnings, and Kate Moss,  36, with $9 million.

Generally, managers and agents   deduct anywhere from 10 to 20 percent commission for each gig a model lands, which includes television commercials and print or online advertisements.

Working Girls

Professional models make up a very small chunk of the work force. In 2008, there were 2,200 models employed by agencies. That number is expected to grow only slightly to 2,600 by 2018, according to the Bureau of Labor Statistics.

Most working models start their careers at age 16.

All professional models have  ”a book,” a photo portfolio of their best shots, usually put together by their agencies or managers. Fees vary, but models typically pay $750 to $1,000 for their book, according to the Better Business Bureau.

Reaching New Heights

For models who want to do  high fashion — runway, pose for power brands such as Chanel, Gucci – the New York Better Business Career Services website says they need to  fit the following requirements:

Female Models:  Height: 5’9?- 6'  Weight: 110 to 130 pounds, from minimum to maximum height respectively 

Male Models: Height: 5’11? – 6’2?  Weight: 140 to 165 pounds, from minimum to maximum height, respectively  Suit Size: 39 – 40, regular to long  Shirt: 15  - 15 1/2  neck, 32-34 sleeve  Waist: 29? – 32?  

But Mary Clarke, an agent for Mother Model Management, points out that having a model’s body depends more on porportion and measurements, not a hard weight number.

“Honestly, with every model it is so different based on age, rate of development, response from clients,” she wrote in an email to ABC News.