To be under 50 mg of residual caffeine at an 11 PM bedtime, have your last Small 12 oz of McDonald's McCafe Coffee (109 mg) by 5:15 PM (17:15). The math uses the median 5-hour caffeine half-life; individual half-lives range from about 2 to 12 hours.
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McDonald's McCafe Coffee Last-Call Times by Bedtime
Latest time to finish a Small 12 oz of McDonald's McCafe Coffee (109 mg of caffeine) and still be under 50 mg of residual caffeine at bedtime, assuming the median 5-hour half-life. Your personal half-life may sit anywhere in the 2 to 12 hour range.
| Bedtime | Last call for McDonald's McCafe Coffee | Residual at bedtime |
|---|---|---|
| 9:00 PM (21:00) | 3:15 PM (15:15) | ~49 mg |
| 10:00 PM (22:00) | 4:15 PM (16:15) | ~49 mg |
| 11:00 PM (23:00) | 5:15 PM (17:15) | ~49 mg |
| 12:00 AM (00:00, midnight) | 6:15 PM (18:15) | ~49 mg |
Clearance Time by Serving Size
How long each serving of McDonald's McCafe Coffee needs before bed to drop under 50 mg:
| Serving | Caffeine | Time needed before bed |
|---|---|---|
| Small 12 oz | 109 mg | 5 h 38 min |
| Medium 16 oz | 145 mg | 7 h 41 min |
| Large 21 oz | 180 mg | 9 h 15 min |
Source: caffeine figures from Caffeine Informer (figures obtained from McDonald's customer service, USDA-based estimates), accessed 2026-06-11. Values can vary by batch, location, and preparation; check the label or the source for the latest figures.
How the Math Works
Caffeine leaves your body by exponential decay. With the median 5-hour half-life, the 109 mg in a Small 12 oz of McDonald's McCafe Coffee falls to 55 mg after 5 hours and 27 mg after 10 hours. To get under 50 mg, the level where caffeine stops measurably delaying sleep for most people, it needs about 5 h 38 min of clearance time. Subtract that from your bedtime and you get the last-call times above, rounded down to the nearest 15 minutes.
The big caveat: the 5-hour figure is a median. Depending on CYP1A2 genetics, medications, smoking, and pregnancy, real half-lives run from about 2 to 12 hours. If caffeine reliably keeps you up, treat these times as too generous and move your personal cutoff earlier, or model your own curve in the caffeine half-life calculator.
