Last updated: June 14, 2026
Our database uses lab-verified HPLC data from published studies and manufacturer specifications. However, actual caffeine content varies by brand, roast level, brewing method, and serving size. Use these numbers as estimates, not exact measurements.
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 (genetic variant *1A/*1A) clear caffeine in 1.5-3 hours. Slow metabolizers (*1F/*1F) take 8-10 hours. If you are slow, 200mg feels like 400mg to a fast metabolizer. Genetics determine which type you are.
Our Pregnancy Limit Tool is designed to help you stay within the 200mg NHS/FDA recommendation. However, always consult your healthcare provider for personalized advice. Every pregnancy is different.
Web-based tools work on every device without downloads, updates, or app store approvals. More importantly, browser-based localStorage keeps your data on your device — no cloud servers, no data breaches, no privacy concerns.
Each tool has a "Clear All" button that removes all saved data for that tool. You can also clear all site data through your browser settings: Settings > Privacy > Clear browsing data > Cookies and site data.
Not currently. CaffeineCheck is designed for individual browser-based use. If you are a researcher interested in our dataset, contact us directly.