Transparent calculations

How CaffCalc works

The calculator is an educational model. It estimates caffeine remaining; it cannot measure blood caffeine or predict how you will sleep.

The formula

Each drink is calculated independently at its local consumption time, then the estimates are added together. The tracker samples the same equation every 30 minutes; changing the half-life redraws the estimate.

Why half-life is adjustable

Caffeine clearance differs between people and circumstances. The default is five hours, while the results also show three-, five- and seven-hour scenarios to make that uncertainty visible.

Tracker dates and history

The tracker assigns an entry to a calendar day using the time zone reported by the browser. Seven-day statistics are descriptive summaries of the entries stored on that device. They are not physiological measurements or health targets.

What the thresholds mean

The 50, 25 and 10 mg times are navigation aids, not medically validated sleep or safety limits. The coffee equivalent uses 95 mg as a representative brewed-coffee serving.

Limitations

• Absorption is treated as immediate.
• The model assumes exponential clearance at a constant rate.
• Drink caffeine values are estimates unless you enter a labelled dose.
• Pregnancy, medicines, smoking, genetics and health conditions may change clearance.

For medical or pregnancy-specific advice, speak to a qualified healthcare professional.