A recent study by Arizona news station KSDK found that men hold onto their underpants for an average time of seven years - or basically, until they fall apart.
Human nature is such that we often keep hold of everyday items much longer than we should; we've all got a pair of ancient fallback pants stashed in the back of our closet or a mildewy razor that we run under a tap because we're too lazy to pop out and buy a new one. But how long should you randomly stab at your mascara tube before admitting defeat and throwing it away? And how many days can you keep that leftover florentina pizza in the fridge before food poisoning becomes inevitable?
Here, we look at the shelf life of ordinary house items, from pillows to trainers and moisturiser. Read on to find out when it's time to throw things out and how you can tell whether an item is out of date:
Photos: Rex Features
Your bra - every six to nine months
Be gone that dingy grey bra at the bottom of your sock drawer. According to online expert Linda the Bra Lady, an average bra's shelf life is six to nine months, depending on how often you wear it, how well it's made and whether you change size during that time. If the straps have lost their elasticity and the cups have lost their shape or are not supporting your bust properly, it's time to call it a day.
Your pillow - every 18 to 24 months
A good pillow is key to a proper night's sleep. The folks at Overstock.com reckon that if you have to repeatedly fluff and punch yours into shape before going to bed at night, you need to buy a new one. Treat 18 to 24 months as your hallmark for replacement but if you're unsure, try the fold test - fold your pillow in half and hold for 30 seconds, then release. It should spring back into place and if it doesn't, ditch it (this will also get rid of dust mites that build up over time).
Your refrigerated cheese: every one to four weeks
Softer cheeses like feta have a shorter shelf life (around one week) than hard cheeses such as cheddar, which go off after three to four weeks. ShopSmart magazine editor Lisa Lee Freeman recommends examining your cheese, instead of just using the sell-by date: look for signs of mould and the smell of ammonia. You can prolong your cheese going out of date by replacing store wrapping with wax paper immediately after buying it.
Your mascara - every three months
The general rule of thumb is that mascaras are like toothbrushes, in that you should replace them every three to four months. Many of us trundle on beyond that, trying to eek out clumpy bits of leftover liquid. But mascara is one of the quickest types of make-up to dry and it also builds up bacteria on the brush. Cutting loose at around the three-month mark will help avoid an infection and keep your eyes looking fresh.
Your running trainers - every 450 to 550 miles
We've all got a pair of ancient, worndown trainers in the back of our closet, but the truth is that old running shoes can quickly lead to injury. Clifton Bradeley, podiatrist at Asics, says you should look at replacing trainers every 450 to 550 miles. Any muscle problems when you run, especially knee pain, may indicate that your trainers have lost their cushioning (look at the midsole rather than tread for signs of this).
Your dispensable razor - every three shaves
The temptation is to reach for whatever razor lies within reach in your bathroom cabinet, but the blade on dispensable models quickly becomes worn and bacteria builds up. Debra Jaliman, M.D., a clinical instructor at the Mount Sinai School of Medicine, recommends replacing your razor after three shaves - or changing the blade on a non-dispensable razor once a week - to avoid rashes and cuts.
Your mattress - every five to seven years
You spend almost a third of your life asleep, so it's important that you have a nice mattress to kick back on. How often you replace it depends on its quality; cheaper ones may last only two years and very high quality ones could see out around 10 years. But The Sleep Council recommends aiming for the five to seven year mark. If you wake up feeling stiff with neck or back pain, see a dip in your mattress or if it's creaky when you move, it's time to change.
Your leftovers - every three to four days
Whether it's stone-cold pizza or a slightly congealed Chinese takeaway, your leftovers should stay in the fridge no more than four days. If you think it'll take you longer than that to eat leftovers, freeze them immediately, says nutritionist Katherine Zeratsky, of Mayoclinic.org. It's also better to put your leftovers in the fridge straight away after eating (so the cold can kill off bacteria more quickly) and use shallow dishes for storage.
Your kitchen sponge - every two to three washes
Sponges can soak up bacteria at an alarming rate and even washing them thoroughly won't keep the germs at bay. "There is a forest of bacteria, spores, even pathogens, in a sponge—not just one single culture," says Dr. Roxanne B. Sukol, medical director of the Cleveland Clinic's Wellness Enterprise. You could try running your sponge through a regular machine dishwashing cycle, but should look at replacing it every two to three washes - or use paper towels instead.
Your moisturiser - every two years
How long your moisturiser lasts depends on how many active ingredients it contains (like SPF) and how vulnerable it is to bacteria (like dipping your fingers in a face cream). Sarah Smith of RealSimple.com says most skincare products contain preservatives to help them last longer. A general rule is to throw out opened tubs and tubes after two years, and give three years for sealed products. Also keep an eye on the product's smell and texture.