Caffeine is a stable molecule. It survives roasting largely intact, and it does not meaningfully degrade in storage.
What actually changes
Stale coffee loses aromatic compounds and gains oxidized, cardboard-like flavors. The caffeine is still there.
A six-month-old bag will taste flat and will wake you up exactly as much.
Roast level barely matters either
Dark roasting destroys a small amount of caffeine, but dark-roasted beans are also less dense, so a scoop of dark roast has less coffee in it than a scoop of light.
By weight, light and dark roasts are within a few percent of each other. By volume, light roast has more.
Weigh your coffee and the question disappears.
What does change caffeine in the cup
Brew method and ratio, far more than any bean property. A French press at 1:15 has more caffeine per serving than an espresso, despite espresso being far more concentrated.
Species. Robusta has roughly twice the caffeine of arabica. This is the one bean factor that genuinely matters.
Grind and contact time, since caffeine extracts along with everything else — but it extracts early and fully, so the effect is small in practice.
The practical answer
If you want less caffeine, change the drink or the ratio, or buy decaf. Do not rely on old beans or dark roast.
What people want to know
Does reheated coffee lose caffeine?
No. Reheating does not break down caffeine; it only drives off aroma and makes the coffee taste more bitter and stale.
Last reviewed 30 October 2026