Most people assume being good-looking gives you a career boost. But just how much does it help?

A lot. Good-looking people charm interviewers, get hired faster, are more likely to make more sales and get more raises.

Daniel Hamermesh, an economics professor at the University of Texas in Austin, measures out the benefits in his book, "Beauty Pays: Why Attractive People Are More Successful."

According to his research, attractive people are likely to earn an average of 3% to 4% more than a person with below-average looks. That adds up to $230,000 more over a lifetime for the typical good-looking person, Dr. Hamermesh estimates. Even an average-looking worker is likely to make $140,000 more over a lifetime than an ugly worker.

We asked Dr. Hamermesh to discuss his findings. Edited excerpts follow:

WSJ: You show that good looks are even more influential for men's earnings than for women's. Why do men's good looks pay off more?

Mr. Hamermesh: There are two reasons. First, not as many women work for pay as men. (The Bureau of Labor Statistics says just 59% of adult women hold paying jobs in the workforce, compared with 73% of men.) If you are unattractive and you know you are going to be penalized for that, and if you have an option to stay out of the job market, you as a woman may choose not to bear that pain. Also, women in general are paid less than men; part of it is that they channel themselves into different occupations, and part of it is pure discrimination.

WSJ: What about the argument that better-looking people tend to sell more products or attract more new customers?

Mr. Hamermesh: Yes, [research] shows that happens. Better-looking workers bring in more for the employers, just as a more intelligent worker will. Paying them more is still a form of discrimination, but their attractiveness also tends to raise their productivity. That's what makes it so difficult. I would argue that this is discrimination. But others would argue that it's simply an indulgence of people's tastes and preferences.

WSJ: If you are unattractive, what can you do to improve your odds of getting paid well?

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Mr. Hamermesh: Looks are only one of many things that affect how much we earn, including education, age, health, company size and so on. But to your question: First, don't go into an occupation where looks matter a lot. Don't be a TV broadcaster; be a radio broadcaster. Don't be a movie actor. Most important, go into fields that you enjoy, and that you have an advantage in doing. Accentuate your strengths, and try to avoid those things where you are relatively disadvantaged.

WSJ: Are there examples of occupations where you don't have to be beautiful?

Mr. Hamermesh: You would think you could find examples of occupations where being unattractive wouldn't hurt you at all. But in every one I have looked at, being better looking helps you. For example, you wouldn't think it would matter much if you are teaching in college. But based on my studies, better-looking [professors] are more appreciated by their students. The only counter-example I've seen is a study showing that if you [commit] armed robbery or theft, it pays to be uglier. The white-collar criminals are more successful if they are better-looking, but for crimes involving force, I'd rather be an ugly robber because I'd scare the guys and they'd give me their money faster.

WSJ: Isn't this unfair?

Mr. Hamermesh: Yes.

WSJ: Should something be done about it?

Mr. Hamermesh: It's a complicated issue. On one hand, I don't view this as very different from other forms of discrimination, whether it is based on race, gender or certainly disability; discrimination based on disability is analogous. Given that similarity, I find it very hard to oppose offering protections and trying to remove this kind of discrimination. On the other hand, we may not want the government to get involved, because if officials intervene on behalf of unattractive people, they will end up doing less for other groups which are regarded as more deserving.

WSJ: So what constitutes beauty?

Mr. Hamermesh: There is no unique view about beauty – no unique standard. But most beholders view beauty similarly. Some people are consistently regarded as above-average or even beautiful, while others are generally regarded as plain or even downright homely.

WSJ: For those of us who are beauty-challenged, what about plastic surgery?

Mr. Hamermesh: I know of only one serious study on that, and that research suggests it isn't a good investment. While looks can be altered by clothing, cosmetics and other short-term investments, the effects of these improvements are minor. We are generally stuck with what nature has given us in the way of looks. Surgery pays back less than $1 for every $1 spent. But it might make you feel better.

Write to Sue Shellenbarger at Sue.Shellenbarger@wsj.com