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Brewed coffee before bed: 96 mg of caffeine and how long it lasts
Updated October 5, 2026 · Sources: Mayo Clinic · U.S. Department of Agriculture · U.S. Food and Drug Administration · National Academies Press
Short answer
96 mg
per 8 fl oz (237 ml)
9 h 42 min
until under 25 mg is left
Half of the 96 mg is still in you 5 hours after the cup, and a quarter after 10. For a normal-sized cup that puts the finish-by time almost 10 hours before lights out.
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.
After 5 hours about 48 mg remain. After 10 hours, 24 mg. That second number explains the finish-by time: a 96 mg cup only slips under the 25 mg line a little before the 10-hour mark. The curve models an average adult. Half-lives measured in people run from 1.5 to 9.5 hours (Institute of Medicine, 2001), so your own line can sit well above or below this one.
01Last brewed coffee 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 | 11:15 am | 42 mg | 63 mg |
| 9:30 pm | 11:45 am | 42 mg | 63 mg |
| 10:00 pm | 12:15 pm | 42 mg | 63 mg |
| 10:30 pm | 12:45 pm | 42 mg | 63 mg |
| 11:00 pm | 1:15 pm | 42 mg | 63 mg |
| 11:30 pm | 1:45 pm | 42 mg | 63 mg |
| 12:00 am | 2:15 pm | 42 mg | 63 mg |
| 12:30 am | 2:45 pm | 42 mg | 63 mg |
| 1:00 am | 3:15 pm | 42 mg | 63 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.
02How much one cup really varies
One cup is not one number. The two government sources fetched for this page disagree by about a factor of two on a 12 fl oz serving. The USDA average for brewed coffee works out to 142 mg, while the FDA lists 113 to 247 mg for regular brewed, non-specialty coffee in the same size.
USDA's own measurements run from 30 to 44 mg per 100 g across 8 data points, which puts an 8 fl oz cup between about 71 and 104 mg. The FDA range is wider because it covers many coffees rather than one. Neither source splits its figures by roast or brew time, so this page does not either.
Size is the lever you control. The same brew gives about 95 mg in 8 fl oz, 142 mg in 12 and 189 mg in 16. A large take-away cup can hold twice the 96 mg this page leads with. At 142 mg the time to fall under 25 mg stretches to about 12 h 30 min, and at 189 mg to about 14 h 35 min, so move the finish-by time earlier by the same amount.
| Serving or brew | Caffeine | Basis | Source |
|---|---|---|---|
| 8 fl oz brewed (headline figure) | 96 (80–100) | Typical figure from the Mayo Clinic caffeine chart, as stored in the site data | Mayo Clinic |
| 8 fl oz brewed, 237 g | 95 (71–104) | 40.0 mg per 100 g, measured range 30–44, 8 data points; multiplied by 237 g | USDA FDC 171890 |
| 12 fl oz brewed, 355 g | 142 (107–156) | Same USDA figures multiplied by 355.2 g (12 × 29.6 g per fl oz) | USDA FDC 171890 |
| 16 fl oz brewed, 474 g | 189 (142–208) | Same USDA figures multiplied by 473.6 g (16 × 29.6 g per fl oz) | USDA FDC 171890 |
| 12 fl oz, regular brewed non-specialty | 113–247 | FDA consumer update, per 12 fl oz serving | FDA |
| 1 cup breakfast blend, 248 g | 92 | 37.0 mg per 100 g; multiplied by the 248 g cup listed by USDA | USDA FDC 171881 |
| 8 fl oz decaf | 2–15 | FDA: "decaf coffee typically has 2 to 15 milligrams in an 8-fluid-ounce cup" | FDA |
Per-serving values for 8, 12 and 16 fl oz are calculated by DozeClock from USDA mg per 100 g and the USDA gram weight of a fluid ounce (29.6 g); they are not measured values for those cup sizes.
03Brewed coffee next to the three nearest drinks
| Drink | Serving | mg | Hours to under 25 mg | Finish by for an 11 pm bed |
|---|---|---|---|---|
| Brewed coffee | 8 fl oz (237 ml) | 96 | 9 h 42 min | 1:15 pm |
| 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 |
mg per serving, not per ounce: servings differ in size · nearest = smallest difference in mg per serving (data/caffeine.json)
Per fluid ounce, brewed coffee carries about 12 mg, the energy drink in the data about 9 and matcha about 9. Espresso is far stronger by volume at 64 mg in a single 1 fl oz shot, but the serving is small: a double shot, at two servings, lands near 128 mg, which is more than a cup of brewed coffee. Compare servings, not drink names.
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, prepared with tap water (SR Legacy, FDC ID 171890) — U.S. Department of Agriculture
- Spilling the Beans: How Much Caffeine is Too Much? — U.S. Food and Drug Administration
- 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.