Roasted coffee does not go off in a way that will hurt you. It is dry, and dry things do not support the microbes that spoil food. That is why best-before dates on coffee sit two years out.
What it does is go flat, and that happens on a much shorter schedule.
The timeline
Days 0 to 4 — too fresh. Still releasing CO₂, which makes extraction uneven.
Days 5 to 35 — the useful window.
6 weeks to 3 months — the distinctive aromatics have largely gone. Still recognisably coffee, no longer recognisably Ethiopian.
Beyond 6 months — cardboard, generically bitter, sometimes a stale-oil note from dark roasts.
Ground coffee
Minutes, not weeks, for the volatile aromatics. This is not an exaggeration — most of what makes coffee smell like coffee is gone within fifteen minutes of grinding.
When it genuinely is unsafe
Visible mould, which requires moisture — a bag stored damp, or beans returned to a container while wet.
Rancid oils on very dark roasts kept warm for a long time. Unpleasant rather than dangerous.
Brewed coffee left out is a different matter: it is wet, and it will grow things within a day. Refrigerate it or throw it away.
The practical rule
Buy small, check the roast date, finish it in three weeks.
Last reviewed 8 August 2026