To be under 50 mg of residual caffeine at an 11 PM bedtime, have your last Single shot 1 oz of Espresso (64 mg) by 9:00 PM (21:00). The math uses the median 5-hour caffeine half-life; individual half-lives range from about 2 to 12 hours.
Espresso Last-Call Times by Bedtime
Latest time to finish a Single shot 1 oz of Espresso (64 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 Espresso | Residual at bedtime |
|---|---|---|
| 9:00 PM (21:00) | 7:00 PM (19:00) | ~49 mg |
| 10:00 PM (22:00) | 8:00 PM (20:00) | ~49 mg |
| 11:00 PM (23:00) | 9:00 PM (21:00) | ~49 mg |
| 12:00 AM (00:00, midnight) | 10:00 PM (22:00) | ~49 mg |
Clearance Time by Serving Size
How long each serving of Espresso needs before bed to drop under 50 mg:
| Serving | Caffeine | Time needed before bed |
|---|---|---|
| Single shot 1 oz | 64 mg | 1 h 47 min |
| Double shot 2 oz | 127 mg | 6 h 44 min |
Source: caffeine figures from USDA FoodData Central, FDC ID 171891 (Beverages, coffee, brewed, espresso, restaurant-prepared, SR Legacy), 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 64 mg in a Single shot 1 oz of Espresso falls to 32 mg after 5 hours and 16 mg after 10 hours. To get under 50 mg, the level where caffeine stops measurably delaying sleep for most people, it needs about 1 h 47 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.