Coffee Data Lab
The Caffeine Calculator
Pick a drink, set how many cups you have a day, and see your total against the 400 mg guideline used by food-safety authorities. Every figure below is sourced, and where our sources disagree, we show the range instead of pretending there's one true number.
The Caffeine Calculator
Every drink in our database is sourced from lab analyses and manufacturer disclosures — and when the sources disagree, we show you the range, not a guess. Compare your daily intake against the 400 mg guideline used by food-safety authorities.
How we source these numbers
Three inputs, one reconciled range.
Lab analyses
Independent testing (typically HPLC) gives the most granular per-batch numbers — but sample sizes are small, and results shift with bean origin, roast level and brew method, so a single lab result is a data point, not a verdict.
Manufacturer disclosures
Brand-published labels and regulatory filings are consistent and easy to cite, but they're often rounded conservatively and don't capture how your local café or your own kitchen actually brews the drink.
Reconciled ranges
When lab data and manufacturer numbers disagree — which happens more than you'd think — we publish the full spread with every source cited, and use the midpoint as our default estimate above.
The database, in brief
Six drinks, sourced and ranged.
| Drink | Typical | Sourced range |
|---|---|---|
| Espresso — single shot | 63 mg | 58–69 mg |
| Espresso — double shot | 126 mg | 116–138 mg |
| Drip coffee — 250 ml | 145 mg | 120–180 mg |
| Cold brew — 300 ml | 200 mg | 155–280 mg |
| Black tea — 250 ml | 47 mg | 40–60 mg |
| Energy drink — 250 ml | 80 mg | 70–100 mg |
Questions people actually ask
Is 400 mg of caffeine a day safe?
For most healthy adults, food-safety authorities cite roughly 400 mg a day — about four 250 ml cups of drip coffee — as an amount not generally associated with adverse effects. It's a population guideline, not a personal limit: pregnancy, certain medications, anxiety sensitivity and individual metabolism all shift where "too much" starts for any one person. Some people feel jittery well under 400 mg; others sit comfortably above it. Treat the number as a reference point, not medical advice — for specific health concerns, a doctor is the right person to ask.
Does espresso have more caffeine than drip coffee?
Per ounce, yes — espresso is far more concentrated, extracted at roughly ten times the strength of drip. But per typical serving, drip usually wins on total caffeine: a 250 ml cup of drip (around 145 mg) contains more than a single espresso shot (about 63 mg), simply because you're drinking a much larger volume. A double shot (about 126 mg) gets closer. So the honest answer depends on what you're comparing — concentration favors espresso, total dose per cup usually favors drip.
What does caffeine's half-life actually mean?
Half-life is the time it takes your body to clear half of the caffeine you consumed. The commonly cited figure is 5–6 hours, meaning a 200 mg dose leaves roughly 100 mg still active five-plus hours later. But that's a population average — genetics, pregnancy, smoking status and other factors can push individual half-lives from under 3 hours to over 9. It's why an identical afternoon coffee wrecks one person's sleep and barely registers for another.
Curious about the mechanism behind that half-life number? Read the sourced breakdown in the Journal.