Should you get an extended warranty on gadgets?

Extended warranty coverage is good only sometimes.

There’s a moment of weakness that strikes shoppers in the checkout aisle. Right after the cashier scans your new gadget, there comes the inevitable question, “Do you want to get the extended warranty?”

Take a moment. This can be a tricky question.

Many shoppers will spend days comparing prices and specs on new electronics, and then hastily decide whether or not to buy a warranty in just a few seconds. So, is it a good deal? For most people, your answer to the pushy salesman should be “no, thanks.”

You might want to get a warranty for digital cameras, a student’s laptop, and other devices that you tote all over town. Continually getting jostled in a bag can push many gadgets into an early retirement.

But for electronics that sit still all day and especially those without any moving parts, extended warranties are almost always a bad idea. If something is defective, it’ll probably break in the first few months, when the free manufacturer’s warranty is still in force. Wear and tear doesn’t affect most products until after their third birthday, when extended warranties usually expire.

If you decline at first, most big chains will give you a few days after the purchase to change your mind. This lets you avoid snap decisions by asking to see warranty details in writing and then taking the brochure home. Better yet, “get the cheapest deal you can on an extended warranty by including the cost of one in your price comparison,” suggests Consumer Reports, which regularly inspects warranties and considers them “notoriously bad deals.”

Green Umbrella presents a different take on product protection. For $9.95 a month, it will give you a three-year warranty on all of your devices and appliances. The subscription covers laptops, iPods, washers, blenders, microwaves, almost all electronics that cost less than $5,000 – but not cellphones. Technology changes too quickly for them to cover phones and still keep monthly charges down, says Jennifer Leuer, general manager of Green Umbrella.

This year-old service, a branch of the Experian credit agency, “is about peace of mind,” she says. “Certainly some people believe in warranties and some don’t.... But we also cover things that many stores don’t. Wal-Mart is not going to offer an extended warranty on your blender.”

That’s because most stores stick to items over $150, and then sell a warranty that costs a percentage of the price tag. Those rates can vary from 5 percent to more than 40 percent.

With the average American spending $1,200 a year on electronics, according to the Consumer Electronics Association, that means Green Umbrella will add about 10 percent onto every purchase in exchange for the extra warranty. But Ms. Leuer adds that the more devices you buy, the more attractive the package.