Before you buy Apple’s iPhone 11, here’s the true cost over your lifetime (you may want to sit down for this)

That’s how much you would make if you invested the money you spent on your smartphone from the age of 18 to 78. Read More...

If you think your family’s smartphone addiction is bleeding you all dry, you don’t know the half of it.

Based on typical smartphone costs and usage patterns, your kids will end up spending a staggering $75,000 apiece on their phones over the course of their lives, according to a recent estimate by valuation company Flipsy.

And even they’re only scratching the surface, because they missed out the biggest cost of all: The opportunity cost of all that money.

If you factor that in, the true lifetime cost of your kids’ love affair with their Apple AAPL, +1.18% iPhone is closer to $300,000.

Apple unveiled the iPhone 11 and iPhone 11 Pro Max on Tuesday. They will be 5.8 inches and 6.5 inches, respectively, and will have four and five extra hours of battery life. And the starting price? $699.

The $300,000 lifetime cost figure is based on the average amount spent per year in the U.S. on cellphones, and the average returns you’d make on that money if you invested it instead from age 18 to age 78 and upgraded every 32 months. That number is also in constant dollars — in other words, it’s after accounting for inflation. Based on current average pricing, that puts your total expense at $12,474.

Americans also spend approximately $88 a year on apps and unlimited data plans typically cost around $80 a month.

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Put that money into an investment account, and factor in long-term returns of around 4% a year after inflation, and you reach that $300,000.

As with all calculations, there are plenty of assumptions about average users. But they help show the value of reducing these bills. Based on these calculations, someone who buys a cheap $150 Android phone every two years, and switches to a $20 a month plan, would add more than $200,000 to their retirement account.

This wouldn’t matter for anyone who is as rich as Croesus (or Jeff Bezos), but it might for plenty of others.

Alas, nearly 40% of families have less than $10,000 in financial assets and about half are at risk of serious financial trouble in retirement. Those estimates are after near-decade-long boom in stock and bond prices. According to a study by the U.S. Government Accountability Office, about half of people nearing retirement have no retirement savings.