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Instant coffee before bed: 62 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
62 mg
per 8 fl oz (237 ml)
6 h 33 min
until under 25 mg is left
The 62 mg cup falls under 25 mg in about 6 hours 30 minutes. What moves that number is the spoon, not the jar.
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.
From 62 mg, about 31 mg is left after 5 hours and about 15 mg after 10. The clock starts when the cup is finished, and instant coffee tends to be sipped slowly, so count from the last sip. Because the dose is modest, the curve crosses the 25 mg line well before a double espresso or a large brewed mug would. The model assumes a 5-hour half-life; in measured adults it runs from 1.5 to 9.5 hours.
01Last instant 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 | 2:25 pm | 27 mg | 41 mg |
| 9:30 pm | 2:55 pm | 27 mg | 41 mg |
| 10:00 pm | 3:25 pm | 27 mg | 41 mg |
| 10:30 pm | 3:55 pm | 27 mg | 41 mg |
| 11:00 pm | 4:25 pm | 27 mg | 41 mg |
| 11:30 pm | 4:55 pm | 27 mg | 41 mg |
| 12:00 am | 5:25 pm | 27 mg | 41 mg |
| 12:30 am | 5:55 pm | 27 mg | 41 mg |
| 1:00 am | 6:25 pm | 27 mg | 41 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.
02Why the range runs from 27 to 173 mg
Instant coffee is measured in powder, then diluted by whoever makes it. USDA lists regular instant coffee powder at 3,140 mg per 100 g, from 15 data points. One level teaspoon weighs 1 g, so it carries about 31 mg, and a 2 g packet about 63 mg.
Run the range backwards and it becomes spoons. A 27 mg cup is under a gram of powder, and a 173 mg cup is about 5.5 g, roughly five level teaspoons. Strong office coffee and a faint cup made from the same jar can sit that far apart without either being a mistake.
USDA also measures the made-up drink: 26 mg per 100 g, which comes to about 47 mg in a 6 fl oz mug (179 g) and about 62 mg in 8 fl oz. That 8 fl oz result lines up with the headline and assumes one typical spoonful of powder per cup, not a heaped one.
Water volume does not change the caffeine, only the taste. Topping a 6 fl oz mug up to 12 fl oz keeps the same milligrams, so a bigger cup of the same spoonful is not a bigger dose. Add a second spoonful and it is.
| Serving or brew | Caffeine | Basis | Source |
|---|---|---|---|
| 8 fl oz made up (headline figure) | 62 (27–173) | Typical figure from the Mayo Clinic caffeine chart, as stored in the site data | Mayo Clinic |
| 8 fl oz made up, 238 g | 62 | 26 mg per 100 g (USDA, prepared with water) multiplied by 238.4 g (8 × 29.8 g per fl oz) | USDA FDC 174130 |
| 6 fl oz mug, 179 g | 47 | 26 mg per 100 g multiplied by the 179 g USDA serving | USDA FDC 174130 |
| 1 level teaspoon of powder, 1 g | 31 | 3,140 mg per 100 g, 15 data points; multiplied by 1 g | USDA FDC 171893 |
| 1 packet of powder, 2 g | 63 | Same figure multiplied by the 2 g packet listed by USDA | USDA FDC 171893 |
| Low end of the site range | 27 | About 0.9 g of powder at 31.4 mg per g, calculated by DozeClock | USDA FDC 171893 |
| High end of the site range | 173 | About 5.5 g of powder at 31.4 mg per g, calculated by DozeClock | USDA FDC 171893 |
| Decaf instant powder, 1.8 g rounded teaspoon | 2 | 122 mg per 100 g, 10 data points; multiplied by 1.8 g | USDA FDC 174133 |
Per-spoon and per-cup values are calculated by DozeClock from USDA mg per 100 g and the USDA gram weights listed on those pages. The 27 and 173 mg ends come from the site data; the gram amounts that would produce them are our arithmetic, not a measured recipe.
03Instant coffee 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)
Instant coffee lands between a cup of black tea and a cup of brewed coffee. In a single serving it is close to one espresso shot (64 mg), which is a handy way to size it: a spoonful of powder is roughly half a shot, so two spoonfuls make one.
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, instant, regular, powder (SR Legacy, FDC ID 171893) — U.S. Department of Agriculture
- FoodData Central: Beverages, coffee, instant, regular, prepared with water (FDC ID 174130) — U.S. Department of Agriculture
- FoodData Central: Beverages, coffee, instant, decaffeinated, powder (FDC ID 174133) — 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.