How long does butter keep at room temperature before bad?

The shelf life of butter at room temperature depends on several factors, including the quality and type of butter, the temperature, and sunlight exposure.

Unsalted butter can typically last at room temperature for about two weeks, while salted butter can last up to a month or longer. However, this is only if these products are stored in an environment where the temperature is consistently between 55°F and 64°F (13°C to 18°C). If stored in a warm area or exposed to sunlight, regardless of the type, the butter will spoil much faster.

If butter is stored at a higher temperature, the fats in the butter will begin to oxidize and the flavor will deteriorate rapidly. Additionally, harmful bacteria can start growing, potentially leading to foodborne illnesses.

To ensure the safety and maintain freshness, butter should be refrigerated to slow the rate of oxidation and prevent bacterial growth.

Always remember to check for any rancid smells, off-coloration, or undesirable flavors before consuming butter that has been left at room temperature for a prolonged time.