Convenience is costly.

Streaming music, TV, movies and video games on demand — and signing up for subscription boxes that deliver groceries, toiletries, clothes, cosmetics and cat toys on a recurring basis — is siphoning away more money than many people realize. In fact, a new Waterstone Management Group survey finds that 84% of Americans grossly underestimate their monthly tech spending.

The consulting firm advises many companies that offer subscription-based models of service, so it wanted to understand how aware the average person is about his or her various monthly subscription expenses.

So researchers surveyed 2,500 Americans; first asking them to spend 10 seconds thinking generally about they spend on “recurring monthly expenses associated with digital services, devices and subscription boxes.“ People guessed they spent $79.74 a month, on average. But when they were prompted to consider some specific examples of services, including Netflix, Spotify, Birchbox, Dollar Shave Club, GoDaddy, Playstation Now, iCloud, Fitbit, etc., they raised their monthly estimate to $111.61 — a 40% increase.

And then when subjects were shown an exhaustive list of subscription services and categories, which was expanded to include the wifi and cellular service required to use these services, as well as wellness apps, gaming services, digital newspaper and magazines subscriptions, meal kits, subscription boxes and more, subjects realized they were actually dropping $237.33 a month on average — a 197% increase from their first guess to what they were actually spending.

“We expected many people to underestimate what they spend each month. We knew from personal experience this was a trend. But we were amazed by how much people underestimate their spend,” Dhaval Moogimane, managing director at Waterstone Management Group, told Moneyish. “People spend more than double what they estimate on subscriptions each month. We’re talking about hundreds of dollars — we did not see that coming!”

As a matter of fact, 55% of U.S. homes are spending $2.1 billion a month on streaming services, according to Deloitte’s 12th annual digital media trends survey, and watching 15 hours of streamed video per week via services like Netflix, Hulu and Amazon Prime Video.

And the subscription e-commerce market has spiked more than 100% percent each year over the past five years, McKinsey & Company reported, with 15% of online shoppers signing up for one or more subscriptions to receive products on a recurring basis (like monthly beauty boxes), with Amazon Subscribe & Save, Dollar Shave Club, Ipsy, Blue Apron and Birchbox reigning the five most popular subscription sites this year, and the industry as a whole made more than $2.6 billion in sales in 2016. Even Jeep announced that it’s joining automakers like BMW, Cadillac and Lincoln in rolling out a subscription service in 2019 that lets drivers to use a vehicle for a monthly fee.

But the grand total creeps up on consumers because the individual services tend to be cheap; Netflix and Hulu start at $8 a month, and while Amazon Prime is $119 for the year, that works out to just under $10 a month. Meal kits average $20 a box, or $60 for the week if you order three meals. Birchbox starts at $10 a month; Dollar Shave Club can run as low as $3 a month. Also, if subscriptions and recurring orders are automatically deducted from your bank account or charged to your credit card, you forget that you’re even paying for them. So it’s not surprising that about one in 10 millennials spend $200 or more every month on subscription services.

“We think many of these things — especially those under $20 — fade into the background and cease to register as something that is ‘paid for’ in the way we pay for other things, like meals at restaurants, a new rug, or even Uber rides,” said Moogimane. “We become used to things like Spotify, Audible, perhaps the New York Times app, as services we have and love and use all the time. They feel a far cry from conscious purchases.”

Meanwhile, the Federal Reserve warns that four in 10 American adults couldn’t cover a $400 emergency expense.  

You don’t have to cancel all of your favorite services, though, especially if you’re actually using and enjoying them. But it pays to sit down and do a subscription audit every couple of months to see whether you’re really getting your money’s worth. For example, 67% of people with gym memberships never use them, even though they’re dropping $58 a month for the privilege of skipping a workout, on average. So if you haven’t used a service (or even touched the goodies that came in that subscription box) then cancel it. And here are some more tips to cutting back on your expensive subscription habits.