What size do you need? Standard mattress dimensions in the U.S. are: twin, 39 inches by 75 inches; double or full, 54 inches by 75 inches; queen, 60 inches by 80 inches; standard king, 76 inches by 80 inches; and California king, 72 inches by 84 inches. Some high-end mattresses don't come in sizes smaller than a queen, so make sure the mattress you try in the store is available in the size you want.
Will it fit in the door? Even within a given size, mattresses vary considerably in thickness. The editors of Good Housekeeping recommend measuring all doorways and hallways to make sure the mattress can fit where it needs to go. If you need to get the mattress up a flight of stairs, make sure there's room to maneuver it in all three dimensions.
How do you sleep? Data collected at SleepLiketheDead.com indicates that people who normally sleep on their sides may need a softer mattress than back or stomach sleepers. However, a mattress of medium firmness is usually comfortable for everyone.
Do you overheat at night? Foam mattresses retain more body heat than innersprings and air mattresses. A latex foam mattress may provide better ventilation than memory foam, but only if the perforations in the latex are big enough to provide sufficient airflow, at least 1 centimeter across.
Will you share the mattress? If your partner is a restless sleeper, you may prefer a foam mattress that transfers less motion than an innerspring. On the other hand, the bounciness of an innerspring may make it more suitable for sex than a squishy foam mattress. SleepLiketheDead.com has more information on how different types of mattresses measure up for this purpose. If you strongly prefer a firm mattress while your partner prefers a soft one or vice versa, your best option may be a dual-chambered air mattress, which can be adjusted to a different level of firmness on each side.
Experts say you should never pay full price for a mattress. The editors of ConsumerReports.org emphasize that the retail markup on mattresses, especially innersprings, is exceptionally high and sales are frequent. It's normal, they say, to find a mattress marked down to half its original retail price, and it's also possible to haggle for an even better deal. Good Housekeeping agrees, saying you should always wait for a sale and be prepared to negotiate.
Visit manufacturers' websites. Before shopping, browse through the different lines to see what features they have, and print out details about the models you're interested in. This gives you a good starting point when you get to the store.
Start at the bottom of the price scale and work up. Mattresses vary tremendously in price, and all but the very cheapest are likely to be sturdy. Once you find something that meets your standards, say the editors of Choice magazine, "there's no need to go any further."
Rest on the mattress for at least 15 minutes. When trying out mattresses in the store, spend five minutes each on your back and both sides as well as your stomach, if that's one of your normal sleeping positions. If you sleep with a partner, try out mattresses together.
Check the firmness. If you have difficulty rolling over, the bed is probably too soft. On the other hand, if you can easily slide your hand under the small of your back while lying on your back -- or if you feel pressure on your hips and shoulders -- it's probably too firm.
Ask to see a cross-section of the mattress. Look at details like the coil size and density of an innerspring mattress, and the foam density and size of ventilation holes on a foam mattress.
For an innerspring mattress, consider a new box spring. Some sources say an old box spring can be kept if it's in good condition, but others say a new one will prolong the life of the mattress. Also, using an old foundation might void the mattress' warranty.
Look for a comfort guarantee. Many retailers will give you a trial period of two weeks to three months on a new mattress. Each store has different rules, and there's usually a fee for returns or exchanges. Make sure to get the details in writing.
Ask about disposal of your old mattress. Some stores offer free disposal; others will charge a fee.
Read the fine print. Make sure the sales contract specifies that the store can't deliver a substitute brand or style if the one you want is out of stock. When your mattress arrives, inspect it to make sure it's the right one and that it's undamaged.
According to research at What's the Best Mattress, buying mattresses online or over the phone has become more common than ever. However, most experts advise against buying a mattress this way, saying it's important to test a mattress in person before purchase.
The editors of ConsumerReports.org say customers who buy a mattress online are more likely to return it than those who buy from a store. Even so, among the 16,000-plus mattress owners surveyed by SleepLikeTheDead.com, those who bought mattresses online, sight unseen, were just as satisfied with their purchases as those who tried them in a showroom. They suggest that a 15-minute test drive may not be an accurate gauge of comfort, and prices and return policies are often better online. Buying this way might be worth the risk if it gets you a much better deal on the mattress you want.