Expiration dates are a sham. Here's the best way to tell if a food has gone bad.

Shutterstock/Christopher Boswell

• Expiration dates are based on rough estimates.
• Americans waste 40% of the food they purchase annually, the equivalent of $218 billion.
• Instead of relying on imprecise sell-by dates, here's the best way to tell if foods like eggs, cheese, fish, or veggies have gone bad, according to science.

The best way to tell if a food is still good to eat isn't necessarily looking at the sell-by date printed on the package.

Expiration dates are based on rough estimates. They can tell you when a carton of eggs or a raw steak will likely reach the limit for their best quality, but that's about it, according to research compiled by the Natural Resources Defense Council (NRDC), a nonprofit environmental organization.

"Millions of Americans are tossing perfectly good food in the trash because they think it's not safe to eat after the date on the package," Dana Gunters, a senior scientist with the National Resources Defense Council, said in a statement last year.

Americans throw away up to 40% of purchased food every year, the equivalent of $218 billion. In addition to the wasted money - about $1,500 per year for a family of four, according to the NRDC - food waste also means that all of the resources that were used to grow, store, and transport food get wasted, too.

Here's how to tell if everything in your refrigerator - including milk, cheese, hummus, and fish - has gone bad.

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