If you buy health insurance on a state or federal marketplace, the arrival of fall means it’s almost time to pick a health plan.

The Affordable Care Act, also called Obamacare, requires most Americans to buy health insurance. This year’s open enrollment period lasts from Nov. 1 to Jan. 31 for anyone buying health insurance on their own, whether for one person or a family. (If you get your health plan through work, your open enrollment time will be decided by your employer.)

Health insurance is intended to save you from financial hardship due to medical bills. Health plans sold through the marketplaces are sorted into metal tiers — bronze, silver, gold or platinum — based on how much they’ll help pay your medical bills, on average.

Here’s how to decide which metal tier is right for you.

Each tier level is meant to estimate the percentage of medical costs the plans will cover, based on an average across all buyers of plans within the tier:

Health plans in every tier must pay for “10 essential health benefits,” which are defined by federal law — things such as trips to the emergency room, pediatric care, prescription drugs and preventive care such as physicals and immunizations. Plans can also pay for treatment beyond these 10 fundamentals, and the overall estimated payments for services determine the tier.

The percentage you pay for each tier, such as 40% for a bronze plan, includes your deductible, copayments and coinsurance. These amounts will vary by plan, even within the same tier. There’s a cap on how much you pay in one year, which also varies by plan. The maximum in 2017 is $7,150 for an individual or $14,300 for a family.

This year, “Simple Choice” plans will be available on the exchanges for some consumers. Deductibles, copayments and coinsurance are the same within each metal tier in these plans to make them easier to compare.

For many people, silver plans seem to strike a good balance between out-of-pocket costs and premiums. Of consumers enrolled in state or federal exchanges as of March 2016, 70% chose a silver plan, according to the Centers for Medicare and Medicaid Services.

Philip Lee, a health insurance broker in Lafayette, Calif., says most of his clients choose silver plans. However, people with more medical needs often upgrade to a gold plan because lower costs at the doctor’s office or pharmacy offset their higher monthly premiums.

After silver plans, bronze plans are the next most popular, with 22% of consumers choosing them in 2016 — perhaps because the premiums are often the lowest available.

The trade-off with a bronze plan is higher out-of-pocket costs when you’re sick and need to see a doctor or fill a prescription. “So if you’re really healthy and will hardly ever be using the plan at all, OK, maybe bronze is a good choice,” Lee says.

On the flip side, Lee almost never recommends a platinum plan to clients because the added benefits typically aren’t worth the high premiums.

“Don’t get a plan you think you might not be able to afford,” says Adria Gross, a patient advocate and author of “Solved! Curing Your Medical Insurance Problems.” If you can’t pay your premiums, the insurer will cancel your plan.

The metal tier is just one of many things to keep in mind when choosing a health insurance plan. “If any plan doesn’t cover your doctors, hospitals and your drugs, it won’t work for you,” Gross says. When making your choice:

If you don’t find this information online, call the insurer’s customer service line and ask any questions you have before you buy.

Lacie Glover is a staff writer at NerdWallet, a personal finance website. Email: lacie@nerdwallet.com. Twitter: @LacieWrites.

This article was written by NerdWallet and was originally published by USA Today.

The article Choosing the Right Health Insurance Plan ‘Metal Tier’ originally appeared on NerdWallet.