Espresso vs Flat white: caffeine compared
Flat white (12 oz) has 130 mg of caffeine, 67 mg more than Espresso (single shot, 63 mg) — 2.1× as much per serving. Per fluid ounce, Espresso is the stronger drink: 63 mg/oz versus 10.8 mg/oz.
| Espresso | Flat white | |
|---|---|---|
| Serving | single shot | 12 oz |
| Caffeine per serving | 63 mg | 130 mg |
| Per fl oz | 63 mg | 10.8 mg |
| Share of 400 mg/day | 16% | 32% |
| Servings to reach 400 mg | 6.3 | 3.1 |
| Hours until under 50 mg | 1.7 h | 6.9 h |
| Last one for an 11 PM bedtime · standard (50 mg) | 9:20 PM | 4:06 PM |
| Last one for an 11 PM bedtime · sensitive (25 mg) | 4:20 PM | 11:06 AM |
| Share of the 200 mg pregnancy limit | 32% | 65% |
One serving of each, over 16 hours
Common questions
Which has more caffeine, Espresso or Flat white?
Flat white (12 oz) has about 130 mg versus 63 mg in Espresso (single shot): 67 mg more, or 2.1× as much.
Which is stronger per ounce, Espresso or Flat white?
Espresso: about 63 mg per fl oz versus 10.8 mg for Flat white. Serving size decides the total you actually drink.
How many Espresso servings equal one Flat white?
About 2.1 servings of Espresso (single shot) match the caffeine in one Flat white (12 oz).
When should I stop drinking Espresso or Flat white before bed?
For an 11 PM bedtime with a 50 mg limit and a 5-hour half-life: last Espresso by 9:20 PM, last Flat white by 4:06 PM. Half-life varies from about 1.5 to 9.5 hours between people.
Method
Caffeine per labeled serving, from the same drink table every calculator here uses (FDA/USDA reference amounts and manufacturer labels; see caffeine content of every drink). Brewed drinks vary batch to batch, so read these as typical values. Decay uses a 5-hour average half-life with a 45-minute absorption ramp; cutoff = bedtime − 5 h × log₂(dose ÷ limit). Percentages use the FDA's 400 mg/day figure for healthy adults and the 200 mg/day limit ACOG gives for pregnancy.
Source — Espresso: USDA FoodData Central (SR Legacy 171891), checked 2026-10-13. 212 mg per 100 g × 30 g (1 fl oz shot).
Source — Flat white: Starbucks — Flat White nutrition (Tall 12 oz), checked 2026-10-13.