Caffeine Intake Calculator

Caffeine scales with dose

Caffeine content tracks coffee dose, not cup folklore: a 23 g pour-over extracts ~230 mg; a 36 g double espresso ~110–130 mg (per-cup extraction is lower); cold brew runs highest per gram (long extraction). "A cup of coffee" is a unit of folklore, not chemistry.

The 400 mg guideline

FDA guidance caps healthy adults at 400 mg/day — roughly two large pour-overs or four espressos. Above it, anxiety, sleep fragmentation, and the 3 pm crash compound. The guideline is a ceiling, not a target: many people feel best at 150–250 mg.

The half-life connects everything

Caffeine's ~5-hour half-life (variable by genetics) means the 3 pm brew is a 10 pm presence and an 8 pm brew is a 3 am one. The sleepmath caffeine-cutoff calculator on this network computes exact cutoffs — the daily total and the timing are two halves of the same ledger.