When to stop drinking half-caff coffee
Half-caff coffee · 8 oz holds about 50 mg of caffeine. That's 0.5× an 8-oz brewed coffee — #61 of 78 drinks on this site, and about 12% of the 400 mg daily ceiling. Pick your bedtime and sensitivity; the cell is the clock time your last one starts — computed with a 5 h average half-life, and the calculator above adjusts live.
Finish your last one by
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Your 50 mg over the next 16 hours
| Bedtime | Sensitive · 25 mg | Standard · 50 mg | Tolerant · 100 mg |
|---|---|---|---|
| 10:00 PM | 5:00 PM | 10:00 PM | 10:00 PM |
| 11:00 PM | 6:00 PM | 11:00 PM | 11:00 PM |
| 12:00 AM | 7:00 PM | 12:00 AM | 12:00 AM |
Source — CSPI caffeine chart (Folgers 1/2 Caff), checked 2026-10-13. 60–80 mg per 12 oz brewed, i.e. 40–53 mg per 8 oz; 50 mg sits inside that range. Published range 40–53 mg.
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Common questions
When should I stop drinking half-caff coffee before bed?
For a 23:00 bedtime at standard sensitivity (50 mg bedtime limit), finish your last half-caff coffee by 11:00 PM. Sensitive readers should shift earlier; tolerant readers later.
Why do the times differ so much between people?
Caffeine half-life ranges 1.5–9.5 h across healthy adults, and dose differs by drink. The same can that clears a fast metabolizer by dinner can still be 50 mg in a slow one at midnight.
Method
Cutoff = bedtime − T½ × log₂(dose ÷ limit), base T½ 5 h, limits 25/50/100 mg. Every cell is computed, not quoted — the cutoff calculator applies the same formula with your metabolism factors.