This varries by brand, but most brands have a use by date on them. For HP it's 2 years from date of manufacture. I have used large HP black carts like the 45 that were a year past the date and they worked. Once the package is open you have a lot less time. 6-12 months max. For newer, smaller cartridges, If there is no date on the package I'd expect at least 12-18 month shelf life but use the oldest ones first. If the cartridge is refilled or re-manufactured, not new, Use as soon as possible. These have a much shorter life, 90 days max as the print heads are open. Always Store Cartridge packages in an upright manner so the print head surface is down.