カフェイン即時蓄積計算機 手動記録で半減期カーブと就寝前の目安を確認
Step 1: Add a manual intake record
This is a manual log, not a background tracker. Once the page is closed, it cannot keep monitoring you; add a record after each drink.
1 means one default serving; use 0.5 or 1.5 for a half cup or a large drink.
Default is 5 hours; real values vary widely by metabolism, medication, age and genetics.
Default 50 mg is only a general reference, not a safety or medical line.
Current estimate
Estimated with Σ dose × 0.5^((now−intake time)/half-life).
Below the common adult 400 mg/day reference limit.
Uses 50 mg as a bedtime remaining-caffeine reference line.
Records are stored only in this browser's localStorage. They may disappear if you switch devices, clear data, or use private browsing.
Next 24 hours caffeine decay curve
The curve uses only the records you manually entered and the half-life setting; it cannot know about drinks you did not log.
Today's records
Honest disclaimer and health notes
- A common adult reference limit is about 400 mg/day (FDA/EFSA), but individual tolerance varies greatly.
- This tool is for manual logging and general information only. It is not medical advice and cannot diagnose sleep, anxiety, or cardiovascular issues.
- Pregnancy, trying to conceive, breastfeeding, teens, arrhythmia, medication use, or caffeine sensitivity may require different limits; follow medical or local official guidance.
カフェイン即時蓄積計算機
このツールは「手動記録＋減衰曲線」に特化しており、常時バックグラウンドで動く健康トラッカーではありません。コーヒー、紅茶、緑茶、エナジードリンク、コーラ、または任意のmg量を飲むたびに自分で追加してください。ページを閉じると静的なフロントエンドは追跡を継続できません。
Caffeine half-life / 咖啡因半衰期
カフェインの半減期は数時間単位で語られることが多いものの、年齢、肝臓での代謝、薬、遺伝的要因によって大きく変わります。このツールは5時間を初期値にし、成人の一般的な目安として400mg/日前後も表示します。参考資料： Wikipedia: Caffeine、FDA caffeine guidance、EFSA caffeine topic
How the 24-hour decay curve works
The calculator uses remaining = Σ dose × 0.5^((t−intakeTime)/halfLife) for the records you manually enter. The dashed line is a bedtime reference threshold, defaulting to about 50 mg. It is a planning aid, not a medical safety line, and it cannot include drinks you forgot to record.
Privacy and related tools
記録はこのブラウザのlocalStorageにだけ保存されます。ブラウザデータを消したり端末を変えたりすると失われる可能性があります。 You can also compare food and drink context with 日本語 Food Calories tool.
Important disclaimer
This is not medical advice. Pregnancy, breastfeeding, teens, heart rhythm issues, anxiety sensitivity, liver conditions, and medication interactions may require different caffeine limits; follow a qualified clinician or your local official guidance.