Generally speaking, it is about 18-24 months, and the specific brand is subject to the time indicated on the package. For unopened milk powder, it is no problem to open it before the shelf life. If it has been opened for a long time and is close to the shelf life, it is not recommended to eat it. Most infant formula milk powder packages clearly stipulate that milk powder should be used up within 1 month after opening. After opening, it will be discarded after more than one month. It is worth reminding that the shelf life date on the milk powder package is the date when it is unopened and in suitable storage conditions. Once opened, this date cannot be passed. In addition, due to environmental factors, milk powder may agglomerate within the specified use date. Normal milk powder should be soft. The unopened milk powder may be affected by the moisture in the air, or a small amount of water drops will inevitably be brought in during the preparation of milk powder, which makes the milk powder moist and hygroscopic and easy to agglomerate. The quality of this milk powder will not change much if the lumps are crushed when kneading. But the caking is big, hard and unbreakable, indicating that the quality of milk powder is not good and should be discarded. Note that the milk powder after opening should be stored in a ventilated and dry place and eaten as soon as possible to reduce waste.