How long does butter last?

Unopened butter stored in the refrigerator at 32-38º F keeps for 4 months, while opened butter or butter stored in the refrigerator door keeps only a couple of weeks.

Form	Where	Official window
unopened	refrigerator	4 months
opened	refrigerator	a couple of weeks
salted butter in a covered dish or butter crock	room temperature	up to one to two days
unsalted butter	refrigerator	removed only briefly to soften before use

The official discard rule

If you are not going to use the butter within a couple of weeks of purchasing it, the butter should be stored in the freezer.

These are the official windows; when in doubt, follow the source linked below.

Grounded in: extension.oregonstate.edu, extension.umaine.edu. Every window above appears verbatim in the linked sources.

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