Tools — CaffeineCheck

Caffeine Tools

All data stays in your browser. We never see your numbers.

Caffeine Intake Calculator

Track your daily caffeine from coffee, tea, energy drinks, and more. Compare against the FDA 400mg limit.

Half-Life Tracker

Visualize caffeine clearance from your body based on your CYP1A2 metabolizer status. See when you're truly caffeine-free.

Tracker SVG Chart

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Sleep Impact Estimator

Estimate how your afternoon coffee affects tonight's sleep. Get a personalized cutoff time based on your sensitivity.

Estimator Personalized

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Pregnancy Caffeine Limit

Stay within the 200mg NHS/FDA pregnancy limit. Budget your daily caffeine by beverage type and trimester.

Safety Trimester-aware

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Energy Drink Comparator

Compare caffeine, taurine, sugar, and stimulants across popular energy drinks. Cost-per-mg analysis included.

Comparison Database

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Withdrawal Timeline

Plan your caffeine taper. See symptom severity by daily dose and generate a personalized tapering schedule.

Planner Taper Schedule

Which Tool Do You Need?

🌅 Morning Routine

Caffeine Calculator — Log your coffee, tea, and pre-workout. See your running total vs the 400mg FDA limit before you reach for that second cup.

🌙 Sleep Worries

Sleep Estimator + Half-Life Tracker — It's 4pm. Should you have that latte? Check your predicted sleep latency and when caffeine actually clears your system.

🤰 Expecting?

Pregnancy Limit Tool — Budget your 200mg daily allowance across beverages. Know exactly which drinks are safe and which push you over.

🔍 Shopping Aisle

Energy Drink Comparator — Compare caffeine-per-dollar, sugar content, and crash risk before you buy. No marketing hype, just numbers.

🔒 Privacy First

All calculations happen in your browser. Your caffeine data is stored in your device's localStorage — we never send it to any server. No accounts, no tracking, no data collection.

12 Caffeine, Fat Oxidation, and the Overweight Athlete — CaffeineCheck

I asked him how much caffeine. “200 mg,” he said. “Sometimes 400.”

May 24, 2026 2026-02-07

07 Growing Brains on Caffeine — CaffeineCheck

The research monkey sat in a cage with a feeding tube. I saw the video during a lecture at a neuroscience conference in 2019.

May 03, 2026 2026-02-07

10 Pre-Workout Powder: 400mg Caffeine + ?? — CaffeineCheck

The scoop was larger than I expected. I’d bought the tub online after reading reviews that promised “laser focus” and “unstoppable energy.” The label ...

March 26, 2026 2026-02-07

14 Pregnancy: When Caffeine's Half-Life Triples — CaffeineCheck

The pregnancy test had two lines. Sam held it up to the light. “Is that positive?” she asked. I took it from her. The second line was faint but there....

March 18, 2026 2026-02-07

08 School Lunch’s Hidden Caffeine — CaffeineCheck

It sold energy drinks. Not the small cans. The tall ones. Sixteen ounces. Labels that screamed “EXTREME” and “POWER” and “ZERO SUGAR.” Bright neon col...

March 15, 2026 2026-02-07

03 Slow Metabolizer‘s Dilemma: CYP1A2 CC and Heart Risk — CaffeineCheck

The mother’s name was Denise. Her son, Tyler, was seventeen. He played football. He was six feet tall, two hundred pounds, no known health problems.

March 13, 2026 2026-02-07