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Espresso before bed: 64 mg of caffeine and how long it lasts
Updated October 5, 2026 · Sources: Mayo Clinic · U.S. Department of Agriculture · U.S. Department of Agriculture · U.S. Department of Agriculture · National Academies Press
Short answer
64 mg
per 1 fl oz (30 ml) shot
6 h 47 min
until under 25 mg is left
A single shot clears the 25 mg line in under 7 hours. Most cafe orders are doubles, though, and a double needs nearly 12 hours.
General information from population studies (NIH, CDC, NSF, AASM). It is not medical advice and does not replace a clinician who knows you.
Model: remaining = dose × 0.5^(hours ÷ 5). Half-life 5 h (Institute of Medicine 2001); real half-lives run 1.5–9.5 h between people.
A 64 mg shot is down to about 32 mg after 5 hours and about 16 mg after 10. The small starting dose is the reason espresso behaves better than its reputation: it is a short curve. The trap is the count. Every extra shot restarts the same decay on top of what is left, so a morning ritual of one shot and an afternoon repeat leaves the first shot still contributing at 4 pm. The curve uses a 5-hour half-life for an average adult, and measured half-lives run from 1.5 to 9.5 hours.
01Last espresso by bedtime
| Bedtime | Finish by (25 mg left) | Left at lights out if finished 6 h before | Left if finished 3 h before |
|---|---|---|---|
| 9:00 pm | 2:10 pm | 28 mg | 42 mg |
| 9:30 pm | 2:40 pm | 28 mg | 42 mg |
| 10:00 pm | 3:10 pm | 28 mg | 42 mg |
| 10:30 pm | 3:40 pm | 28 mg | 42 mg |
| 11:00 pm | 4:10 pm | 28 mg | 42 mg |
| 11:30 pm | 4:40 pm | 28 mg | 42 mg |
| 12:00 am | 5:10 pm | 28 mg | 42 mg |
| 12:30 am | 5:40 pm | 28 mg | 42 mg |
| 1:00 am | 6:10 pm | 28 mg | 42 mg |
Finish-by times are rounded down to 5 minutes. 25 mg is this site's planning line, not a clinical threshold. Every drink at once: caffeine cutoff grid.
02Single, double, triple: the same shot, counted differently
Espresso is the most concentrated coffee on the menu and the least caffeinated per serving. USDA lists restaurant-prepared espresso at 212 mg per 100 g, based on 2 data points, and a fluid ounce of it weighs 29.6 g. That is about 63 mg in one shot, in line with the 64 mg this page leads with.
Stretch the same number across a cup and the picture flips. Eight fluid ounces of espresso would carry roughly 500 mg, five times the 40 mg per 100 g USDA reports for brewed coffee. Nobody drinks that much espresso at once, which is exactly why shots are sold as shots. Strength per ounce tells you about taste; the shot count tells you about sleep.
The count is where bedtime plans go wrong. A double is two shots, about 125 mg, and the time to fall under 25 mg grows from about 6 h 40 min to about 11 h 40 min. A triple, about 188 mg, takes close to 14 h 35 min. If your usual order is a double, plan around the double row below, not the headline.
Decaf espresso is a different product. USDA lists it at 1 mg per 100 g, a figure it rounds to a whole number, which makes one shot a fraction of a milligram. It is not zero, and the source does not tell us how many shots were sampled.
| Serving or brew | Caffeine | Basis | Source |
|---|---|---|---|
| 1 shot, 1 fl oz (headline figure) | 64 (47–75) | Typical figure from the Mayo Clinic caffeine chart, as stored in the site data | Mayo Clinic |
| 1 shot, 1 fl oz, 29.6 g | 63 | 212 mg per 100 g, 2 data points; multiplied by 29.6 g | USDA FDC 171891 |
| Double, 2 fl oz, 59.2 g | 126 | Same USDA figure multiplied by 59.2 g; two shots, calculated by DozeClock | USDA FDC 171891 |
| Triple, 3 fl oz, 88.8 g | 188 | Same USDA figure multiplied by 88.8 g; three shots, calculated by DozeClock | USDA FDC 171891 |
| Per 8 fl oz if it were all espresso | 502 | 212 mg per 100 g multiplied by 236.8 g; for scale only, calculated by DozeClock | USDA FDC 171891 |
| Brewed coffee, 8 fl oz, for scale | 95 | 40.0 mg per 100 g multiplied by 237 g | USDA FDC 171890 |
| Decaf espresso, 1 fl oz | under 1 | 1 mg per 100 g (whole-number value) multiplied by 29.6 g gives about 0.3 mg | USDA FDC 174125 |
Double, triple and 8 fl oz figures are calculated by DozeClock from the USDA mg per 100 g and the 29.6 g USDA weight of one fluid ounce; they are not measured values for those servings. Shot sizes differ between cafes.
03Espresso next to the three nearest drinks
| Drink | Serving | mg | Hours to under 25 mg | Finish by for an 11 pm bed |
|---|---|---|---|---|
| Energy drink | 8 fl oz (237 ml) | 72 | 7 h 38 min | 3:20 pm |
| Matcha (1 tsp powder) | 8 fl oz (237 ml) | 70 | 7 h 26 min | 3:30 pm |
| Espresso | 1 fl oz (30 ml) shot | 64 | 6 h 47 min | 4:10 pm |
| Instant coffee | 8 fl oz (237 ml) | 62 | 6 h 33 min | 4:25 pm |
mg per serving, not per ounce: servings differ in size · nearest = smallest difference in mg per serving (data/caffeine.json)
By volume, espresso is the strongest coffee here. By serving, a single shot (64 mg) sits close to a cup of instant coffee (62 mg), and a double matches a large mug of brewed coffee. Read the serving column in the table, then count how many you actually drink.
Sources
- Caffeine content for coffee, tea, soda and more — Mayo Clinic (figure stored in DozeClock data; page not re-fetched on 2026-10-05)
- FoodData Central: Beverages, coffee, brewed, espresso, restaurant-prepared (SR Legacy, FDC ID 171891) — U.S. Department of Agriculture
- FoodData Central: Beverages, coffee, brewed, espresso, restaurant-prepared, decaffeinated (FDC ID 174125) — U.S. Department of Agriculture
- FoodData Central: Beverages, coffee, brewed, prepared with tap water (FDC ID 171890) — U.S. Department of Agriculture
- Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations — National Academies Press, 2001
General information from population studies (NIH, CDC, NSF, AASM). It is not medical advice and does not replace a clinician who knows you.