Here's how often you have to work out to make a ClassPass membership worth it

Fitness membership program ClassPass became a $400 million company by offering a unique proposition - for $99 a month, you can take as many fitness classes as you like, without committing to a gym.

There are a few caveats.

You're limited to studios that partner with ClassPass, you can only take three classes at each studio per month, and you have to cancel at least 24 hours in advance, or else you'll be charged $20.

Business Insider's Alyson Shontell tested out ClassPass and concluded that the strict cancellation policy was the hardest thing about the service. She also found that classes tended to book up quickly, making it difficult to get a spot if you don't plan far in advance.

So is the $99 a month worth it?

That depends on how often you work out - and where.

If you're a fan of trendy fitness studios with sparkling lobbies, great music, and perks like free hair elastics, it will only take four visits for your ClassPass membership to pay off. With classes costing $20 to $40 on average, you only have to go once a week to make your $99 membership worth it. And if you work out more frequently than that, joining ClassPass could save you a considerable amount of money.

For instance, I could go to:

• Flywheel on Monday ($34)
• Dharma Yoga on Tuesday ($22)
• Pure Barre on Wednesday ($33)
• Warrior Fitness Boot Camp on Thursday ($38)

Without a membership, that would cost me $127 for just four days of workouts. If I paid $99 for a ClassPass membership instead, I'd save $28, and I'd be ahead even if I didn't work out again for the rest of the month.

Of course, you could get a discount at a particular studio by buying a package deal - for instance, at Pure Barre, you can get 20 classes for $500, bringing the price down to $25 per class (which would still take four classes to break even with a ClassPass membership, although you wouldn't be permitted to take four classes at one studio in a single month).

If you take a boutique gym class four times a month, your ClassPass membership would be worth it.

However, let's say you typically look for the cheapest possible class option, and limit yourself to $5 classes at your neighborhood community center or nonprofit yoga collaborative. In that case, you'd pay the equivalent of 20 classes for your monthly membership. If you aren't attending 20 classes a month now and don't plan to start - or an average of five classes a week - you'd be paying more for ClassPass than you do for your current workout, with less flexibility than you currently have.

CLASSPASS, $99/month

Worth it: If you like popular (and pricey) workouts like barre class and spinning, and take four or more classes a month.

Not worth it: If you're on a tight budget, happy sticking with a no-frills workout, and take fewer than three boutique gym classes per month.