For most people, yes: one cup of decaf coffee before bed is unlikely to affect sleep, because it contains only about 2 to 15 mg of caffeine per 8 oz, compared with about 95 mg in regular coffee. Decaf isn't caffeine-free, though. If you're very sensitive, or you drink several cups or decaf espressos in the evening, the small amounts can add up.
Free toolCaffeine Cutoff CalculatorHow much caffeine is still in you at bedtime, and your latest cup.How much caffeine is in decaf?
Decaffeination removes most of the caffeine, not all of it. The FDA puts a typical 8 oz cup of decaf at 2 to 15 mg.
Lab testing shows how much it can vary. In one study, decaf coffees bought from 10 different outlets contained anywhere from 0 to about 14 mg per 16 oz serving. Decaf espresso shots from a single coffee shop ranged from about 3 to 16 mg per shot, even for the same drink ordered repeatedly.
| Drink | Typical caffeine |
|---|---|
| Decaf brewed coffee, 8 oz | 2–15 mg |
| Decaf espresso, 1 shot | about 3–16 mg (one study) |
| Green tea, 8 oz | about 28 mg |
| Brewed coffee, 8 oz | about 95 mg |
So a cup of decaf is usually well under half the caffeine of a cup of green tea, and a small fraction of regular coffee.
How much is left at bedtime?
Using the site's average 5-hour half-life, here's what remains if you drink decaf 2 and a half hours before bed (say 8 PM for a 10:30 PM bedtime) or 1 hour before.
| What you drink | Caffeine | Left after 2.5 h | Left after 1 h |
|---|---|---|---|
| 1 cup decaf, low end | 2 mg | 1 mg | 2 mg |
| 1 cup decaf, typical | 7 mg | 5 mg | 6 mg |
| 1 cup decaf, high end | 15 mg | 11 mg | 13 mg |
| 2 high-caffeine decaf espressos | about 30 mg | 21 mg | 26 mg |
| 3 cups decaf, high end | 45 mg | 32 mg | 39 mg |
The site uses 25 mg at bedtime as a sensible ceiling. One cup of decaf is comfortably below it at any time. Several strong decafs late in the evening can land at or above it, which is roughly what's left from a morning coffee by mid-afternoon.
Want to check a specific drink? The caffeine calculator works with small amounts too.
Who should be more careful
Most people will never notice the caffeine in a cup of decaf. You might want to limit it in the evening if:
- You're very sensitive to caffeine. If a small amount of chocolate or tea keeps you up, decaf's few milligrams may matter to you.
- You clear caffeine slowly. Pregnancy, some medications and liver problems can make caffeine last longer. Ask your doctor if you've been told to avoid caffeine entirely.
- You drink it by the pot. Three or four cups add up.
- You order decaf espresso drinks. Testing suggests decaf shots can vary more than you'd expect.
For more on why the same drink affects people differently, see how long caffeine lasts.
Other reasons decaf might keep you up
If decaf seems to disturb your sleep, caffeine isn't the only possible reason.
- Fluid. A big mug right before bed can mean a trip to the bathroom at 3 AM. Finish drinks an hour or so before bed.
- What's in it. Sugary syrups, whipped cream or a pastry on the side can be more stimulating than the coffee.
- Habit. If coffee has always meant "time to get going," the ritual itself can feel energizing. A warm decaf can instead become a cue to wind down if you make it part of a calm bedtime routine.
Making decaf work at night
- Stick to one regular-size cup in the evening.
- Choose brewed decaf over decaf espresso if you're sensitive.
- Buy decaf you trust. At home, you control the portion and brew.
- Have it with or after dinner rather than right before lights-out.
- Switch to herbal tea if you want a truly caffeine-free warm drink.
To compare decaf with every other common drink, see the caffeine in drinks chart. Once your evening drinks are sorted, use the sleep calculator to pick a bedtime that ends on a full cycle.