How long coffee stays fresh after roasting, and how to tell

Stored well, whole bean coffee keeps good flavor for six to eight weeks after roasting, and it is at its best in the first month. Once ground, that window shrinks to about two or three weeks. After that it does not go bad or make you sick, but it loses its aroma and tastes flat.

Why coffee loses freshness

Roasting fills the bean with gases and aromatic oils. From that moment it starts releasing those gases, and air oxidizes the oils. That is why freshly roasted coffee smells so strong and old coffee barely smells at all.

Grinding speeds everything up. A whole bean protects its inside; ground coffee exposes all of its surface, and much of the aroma is gone within the first few hours.

The first few days

Coffee roasted that same day is still releasing gas. Some people let it rest two or three days before brewing, especially for espresso. For pot brewing, drip or French press, you can drink it from day one.

How to tell if your coffee is fresh

• When you open the bag: the aroma reaches you on its own, without having to put your nose in.
• The hot water test: pour a little hot water over the grounds. Fresh coffee puffs up and bubbles. That foam is the gas it still holds. If the water just sinks in, the coffee has been around a while.
• In the cup: fresh coffee has clear flavors, some sweetness and body. Old coffee tastes flat, dull and bitter, or like cardboard.
• The date that matters: ask when it was roasted. That tells you much more than the expiration date, which can be a year or more away.

How long it lasts at home

As a practical guide, stored well:

• Whole bean: six to eight weeks with good flavor, in a well sealed bag.
• Ground: two to three weeks, well sealed.
• Ground and left open: loses a lot in a few days.

After that it is still drinkable. It just slowly tastes less like the coffee you bought.

The habit that helps most

Buy a little at a time, more often. Instead of a kilo for two months, take home what you will drink in a month or less. That way your coffee is always at its best and you are not paying for aroma that fades in the cupboard.