Should You Refrigerate Butter?
Salted butter doesn't need the fridge. In a covered dish, in a cool spot, it stays fresh and spreadable for a week or two. Keep out only what you'll use in that time — and refrigerate unsalted butter.
Why butter is fine on the counter
Butter is mostly fat, with very little water for bacteria to grow in — and the salt in salted butter is a natural preservative. Kept covered, away from light and heat, it simply stays soft and ready to spread. That's the whole appeal: butter that actually spreads, without tearing your toast.
How to keep it out
Use a covered butter dish or a French butter crock, out of direct sun and away from the heat of the stove. Leave out about a week's worth and keep the rest in the fridge. If it ever smells sharp or tastes a little off, that's rancidity from air and light — toss it and start fresh.
When to reach for the fridge
Chill your butter if it's unsalted (no preservative), if your kitchen runs warm (much above 70°F), or if it's simply more than you'll get through in a week or two. Everything else can live happily on the counter.
I keep mine out on the counter in a covered dish, so it's always soft and ready. And I only buy French butter — the higher butterfat and cultured flavor are worth every penny. Once you've had it, there's no going back.