NEW YORK — Prom-dress trends come and go — bright colors and bohemian looks this season — but the fashion personalities of the high-school girls celebrating the end of the school year in probably the fanciest dress they’ve ever worn are consistent: Every ballroom has its princess, glamour puss, trendsetter and rebel.

“You need to cover a lot of girls, and a lot of girls who want to show their personality, but you always, always need certain styles,” says Michael Shettel, the designer of bridal and eveningwear label Alfred Angelo.

Girls think about their dress — a lot — and they started this process months ago. That means that while red-carpet style and runway looks might influence some girls, you can count on some wanting a retro ’50s ball gown while others want to be all grown up in something slinky with a slit.

Shettel collaborated with Walt Disney Pictures for the movie “Prom” and covered the bases. One of the main characters wears a champagne-colored strapless with a short hemline, another a bright purple corset style, and another in a hippie-esque halter.

High schoolers are a whole “new crop” of girls learning to embrace fashion and use it as a tool of self-expression, says Jane Keltner de Valle, fashion news director of Teen Vogue. The prom outfit is more than just a dress; it’s a statement of who they want to be remembered as with their old friends, and it’s a glimpse at who they will be in the future, she says.

The film accurately mirrors the scenes playing out across the country, Shettel says. Girls go into stores and try on sometimes dozens of dresses, but they know when they hit the right one.

“They might go through a frenzy of dresses, like they’ll try on every green dress. But,” says Shettel, “they’re such quick changers, they’re in and out of the dressing room to show their friends or their parents standing around in the background like lightning.”

Recognizing that girls shop more by type than by specific silhouette, Lord & Taylor is merchandising its prom dresses by personality, says Amy Avitabile, senior vice president of marketing. There’s an online quiz girls can take to guide them.

She breaks it down:

• The trendsetter this year might consider something with cutouts, a one-shoulder neckline or an asymmetrical hemline; neon is a possibility.

• The glamour girl loves embellishment and beading. Look for her in something fit for a princess or a goddess.

• The daring diva will take a plunge with a more revealing neckline and go for a bright color.

• The romantic might be taking style cues from a Taylor Swift type. She likes flowy fabrics, laces, bows and ruffles.

A kooky lace veil, chunky shoe or other bells and whistles are becoming more common as a way to put a personal twist on the outfit, adds Keltner de Valle, but underneath all that, the dresses are typically classic.

That doesn’t necessarily mean timeless, though.

Shettel recalls his own prom date, decades ago, wearing an off-the-shoulder dress in a blue-and-pink floral print, with a ruffle at the neckline and hemline.

How did she look?

“We had a really good time,” he answers with a laugh.