How much caffeine is in your cup?

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6
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400mg
FDA Daily Limit
5h
Avg Half-Life
0
Data Sent to Server

Quick Tools

Most popular calculators and trackers.

Caffeine Calculator

Log beverages and track against the 400mg FDA limit.

Calculator
⏱️

Half-Life Tracker

Visualize caffeine clearance based on your genetics.

Tracker
😴

Sleep Estimator

Get your personal caffeine cutoff time for better sleep.

Estimator

All Tools

Every calculator, tracker, and comparator in one place.

Caffeine Calculator

Track daily intake vs FDA limit.

Calculator
⏱️

Half-Life Tracker

Caffeine clearance by metabolizer type.

Tracker
😴

Sleep Estimator

Personalized cutoff time.

Estimator
🤰

Pregnancy Limit

200mg daily budget by trimester.

Safety
🥤

Energy Drink Comparator

Caffeine, sugar, cost comparison.

Comparison
📉

Withdrawal Timeline

Personalized taper schedule.

Planner
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Seattle Heat Wave Caffeine Toxicity 2026
Caffeine Science

Seattle Heat Wave Caffeine Toxicity 2026

Seattle hit 95°F last Tuesday. I know that doesn't sound like much to people in Phoenix or Dallas. But Seattle is not built for 95 degrees. We don't h...

July 23, 2026 6 min read
Afternoon Coffee Cost Three Nights Sleep
Caffeine Science

Afternoon Coffee Cost Three Nights Sleep

I used to think caffeine had a six-hour half-life. That was the number I carried in my head, the one that let me drink coffee at 3 PM and tell myself ...

July 06, 2026 6 min read
Seattle Heat Wave Caffeine Toxicity
Caffeine Science

Seattle Heat Wave Caffeine Toxicity

My Caffeine Habit Nearly Sent Me to the ER During Seattle's Hottest June on Record Alex Morgan I was on my third cold brew of the day when the dizzine...

July 06, 2026 6 min read
The Monday I Accidentally Drank 600Mg Of Caffeine
Caffeine Science

The Monday I Accidentally Drank 600Mg Of Caffeine

The Monday I Accidentally Drank 600mg of Caffeine Before Noon The pipette did not slip this time. The mistake was much bigger than a smeared calibrati...

June 30, 2026 6 min read
That Pre Workout Powder Has 400Mg Of Caffeine And Thats Not
Caffeine Science

That Pre Workout Powder Has 400Mg Of Caffeine And Thats Not

That Pre-Workout Powder Has 400mg of Caffeine. And That's Not Even the Worst Part. 400 milligrams. That's what the label said. One scoop. Four hundred...

June 24, 2026 6 min read
13 Age Slows Your CYP1A2 — CaffeineCheck
Caffeine Science

13 Age Slows Your CYP1A2 — CaffeineCheck

The first time I noticed it, I was thirty-three. I’d had my usual morning coffee – a 16-ounce pour‑over, about 200 mg of caffeine – and then a second ...

June 03, 2026 6 min read

Common Questions

The FDA recommends 400mg per day for healthy adults. That is about 4 cups of brewed coffee. Pregnant women should stay under 200mg. Teenagers should limit to 100mg.
Yes. All calculations happen in your browser. Your data is stored in localStorage on your own device. We never send it to any server. No accounts, no cookies, no tracking.
CYP1A2 is the liver enzyme that metabolizes caffeine. Fast metabolizers clear caffeine in 1.5-3 hours. Slow metabolizers take 8-10 hours. If you are slow, 200mg feels like 400mg to a fast metabolizer. Genetics determine which type you are.
Yes. All tools are fully responsive and work on mobile, tablet, and desktop. Your localStorage data syncs across sessions on the same device.
Our database uses lab-verified HPLC data from published studies and manufacturer specifications. Actual caffeine content varies by brand, roast level, and brewing method. Use these numbers as estimates, not exact measurements.
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