To be under 50 mg of residual caffeine at an 11 PM bedtime, have your last Tall 12 oz of Starbucks Nitro Cold Brew (215 mg) by 12:15 PM (12:15). The math uses the median 5-hour caffeine half-life; individual half-lives range from about 2 to 12 hours.
Starbucks Nitro Cold Brew Last-Call Times by Bedtime
Latest time to finish a Tall 12 oz of Starbucks Nitro Cold Brew (215 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 Starbucks Nitro Cold Brew | Residual at bedtime |
|---|---|---|
| 9:00 PM (21:00) | 10:15 AM (10:15) | ~48 mg |
| 10:00 PM (22:00) | 11:15 AM (11:15) | ~48 mg |
| 11:00 PM (23:00) | 12:15 PM (12:15) | ~48 mg |
| 12:00 AM (00:00, midnight) | 1:15 PM (13:15) | ~48 mg |
Clearance Time by Serving Size
How long each serving of Starbucks Nitro Cold Brew needs before bed to drop under 50 mg:
| Serving | Caffeine | Time needed before bed |
|---|---|---|
| Tall 12 oz | 215 mg | 10 h 32 min |
| Grande 16 oz | 280 mg | 12 h 26 min |
Source: caffeine figures from Caffeine Informer (values sourced from starbucks.com), 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 215 mg in a Tall 12 oz of Starbucks Nitro Cold Brew falls to 108 mg after 5 hours and 54 mg after 10 hours. To get under 50 mg, the level where caffeine stops measurably delaying sleep for most people, it needs about 10 h 32 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.