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Want to Upgrade Your iPhone? Here Are the Best and Worst Times to Sell or Trade in Your Old One

September 3, 2019, 9:05 PM UTC

With the iPhone 11 rumored to be unveiled on Sept. 10, many current Apple handset owners might be thinking about upgrading their iPhones to defray the cost of Apple’s newest device. But in the world of selling or trading in an old iPhone, timing is everything.

Decluttr, a company that buys and sells used electronics, has released the results of its annual Phone Depreciation Study. The research reveals that smartphone owners who wait until after Apple announces its newest iPhone to trade in their old devices will find values plummeting.

In just the 24 hours after Apple makes a new product announcement, old iPhone trade-in values drop by 30%, the study says

With prices for new iPhones hitting the $1,000 mark and beyond, that lower trade-in value a significant loss. For example, the iPhone XS Apple released last year is currently valued at $646. However, after September 10, when Apple is expected to unveil the iPhone 11, selling an iPhone XS could fetch as little as $452, says the report.

But it’s not just selling iPhones that’s hard on the wallet. Android phones also lose their value at a similar pace. Samsung’s flagship Galaxy S10, released earlier this year, has already lost 57% of its value and is currently worth just $452 at trade-in. Currently, the new price for the iPhone competitor is $999.

And what’s worse, selling an iPhone right before the next one is announced won’t help as much as you might think. According to the study, phones lose the most value in a short amount of time right after they are released. They then then get hit hard again when their successors are unveiled, but those drops—even at 30%—aren’t as significant as the nearly 45% phones lose in value in their first six months.

What’s more, the study suggests that trade-in values decline at a slower rate as time goes on. For instance, after the iPhone X Apple released in 2017, it lost 43% of its value six months after the release date. But it’s dropped just 16% since then. Currently valued at $482, it’s now lost a total of 59% of its initial value.

What does that mean for trading in your iPhone?

If it’s possible to trade in your phone within the first six months, you’ll get the most value for it. If it’s not, to get the best price, trade it in before its successor is announced. But if that’s not doable, don’t fret. You’ll take a hit after a new phone launches. After that, its value will decline, but your new iPhone’s value should hold up relatively well over time.

More must-read stories from Fortune:

—Apple’s planned iPhone unveiling overshadows other big news
Apple Card review: A (mostly) rewarding way to pay—Apple’s AirPods business is bigger than you think
—How to protect yourself against a newly revealed iPhone hack
—Someday, Apple may make your new iPhone out of pieces of your old iPhone
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