Women may amass a great amount of cosmetics for a variety of reasons, whether their favorite lines have released new products or they simply must have this season’s hottest colors.

But while stocking up on products may be simple, the real difficulty can lie in knowing when to toss a beloved item and purchase a replacement. However, with a bit of expert insight, it can be easy to determine the shelf-life of your makeup.

According to Glamour.com, liquid makeup, like concealer, should be replaced every 4 to 9 months, depending upon the type of bottle, as concealers with an airtight seal or pump can last a bit longer than open containers.

Powder formulas, however, can last up to a year, makeup artist Jo Levy told the website, since they collect less bacteria than liquids and creams. But you may want to check items every so often to make sure they are fresh. “If there is a change in color or if the powder contains an odd scent, it’s time for it to be replaced,” Levy added.

Finally, while liquid eyeliners can last as long as a year as well, it’s possible to prolong the life of your liner pencils with proper maintenance. “Remember to continually sharpen the stick of your pencil eyeliners so that bacteria doesn’t settle on it,” makeup artist Molly Stern told the news source.