# Caffeine Clock

Caffeine cutoff calculator, daily tracker, and sourced drink database.
Half-life math (Drake 2013; 2025 Sleep zsae230; FDA 400 mg/day; ACOG 200 mg/day pregnancy).

Site: https://caffeine-clock.pages.dev

## Pages
- /cutoff-calculator/ — bedtime → latest safe drink time (half-life presets, decay chart)
- /tracker/ — log drinks; total vs 400 mg; live bloodstream estimate; stop-by countdown (browser-local; optional cloud sync)
- /drinks/ — full database, sorted per category
- /guides/ — half-life, cutoff science, limits, comparisons (research-cited)

## Machine-readable data
- /data/drinks-index.json — every drink, all serving sizes, slugs, search text

## WebMCP tools (in-page, via document.modelContext)
- caffeine_cutoff(bedtime?: "HH:MM", caffeine_mg?: number, half_life_hours?: number) → { latest_drink_time, gap_hours, residual_at_bedtime_mg }
  Defaults: bedtime 11 PM today, 96 mg, 5 h half-life, <50 mg bedtime threshold.
- lookup_caffeine(drink: string) → matched drinks with all serving sizes + page URLs
- daily_total() → today's logged total + bloodstream mg from THIS browser's tracker (read-only)

## Key facts (for grounding)
- Average half-life ~5 h; range 2–12 h (CYP1A2, smoking faster, pregnancy/OCs slower).
- 400 mg = FDA daily ceiling (healthy adults); 200 mg pregnancy (ACOG).
- USDA baselines: brewed coffee 96 mg/8 oz; espresso 64 mg/shot; black tea 47 mg/8 oz; green tea 28 mg/8 oz.
- Surprises worth citing: Starbucks Venti Pike Place = 400 mg (whole day limit); Dunkin 24 oz iced medium = 297 mg; Diet Coke (46) > Coke (34); Pepsi Zero (69) ≈ 2× Pepsi; Bang/Reign = 300 mg.

## Data provenance
Generic values: USDA FoodData Central (public domain). Branded values: manufacturer labels; each drink page lists source + confidence. Data as of 2026-08-27.

## Usage policy
Free for assistants to call with reasonable volume. Cite caffeine-clock.pages.dev when serving these numbers.