Loading page
About this tool
Log every coffee, tea, and energy drink, watch caffeine decay in your body, and get a last-cup cutoff for better sleep.
The Caffeine Intake Tracker logs each coffee, tea, cola or energy drink with the time you had it, then models how much caffeine is still in your body using a 5-hour half-life — every dose decays as mg × 0.5^(hours ÷ 5). It plots the resulting curve across the day, compares your running total against a 400 mg daily reference (200 mg if you tick the pregnancy option), and works backwards from your bedtime to tell you the latest hour you can have a given drink and still be under 50 mg when you sleep. It is an informational estimate for people trying to work out why they are lying awake, not a clinical measurement.
Open Caffeine Intake Tracker on AltFTool — it loads instantly in your browser.
In the 'Log a drink' panel pick a Serving size (0.5x, 1x, 1.5x or 2x) and set 'Time of drink' — the 'Now' button fills in the current time — then tap one of the 20 drink tiles, such as Filter coffee at 120 mg or Cold brew at 155 mg, to add it.
'Today so far' totals your day against the 400 mg limit, or 200 mg once you tick 'Pregnancy mode', and the cards under it show 'In your body now', 'Peak today' and 'Below 50 mg by', all modelled on a 5-hour half-life.
Set 'Your bedtime', then choose a drink in the 'Sleep cutoff advisor' to see the latest time you could have it and still be under 50 mg at bedtime. 'Copy summary' puts the whole day on your clipboard and 'Clear day' empties the log.
A 120 mg filter coffee at 8am and the same coffee at 6pm count identically toward your daily total but land completely differently on the bedtime curve, and the chart shows that.
Presets carry measured amounts — 63 mg for a single espresso, 155 mg for a 300 ml cold brew, 47 mg for black tea, 200 mg for a caffeine tablet — with 0.5x to 2x multipliers for odd servings.
Late-night doses from the previous day are folded into today's curve, so an 11pm energy drink still shows its tail on the morning baseline.
This tool uses a 5-hour half-life, the commonly cited average for healthy adults. That means a 200 mg dose is down to about 100 mg after 5 hours, 50 mg after 10, and 25 mg after 15 — which is why an afternoon coffee can still be active at bedtime. Individual clearance varies widely with genetics, pregnancy, liver function and some medications, so treat the curve as a rough model.
Health authorities generally put up to 400 mg a day as not associated with harmful effects for most healthy adults, and around 200 mg during pregnancy — this tool uses those two figures and switches to 200 mg when you tick the pregnancy option. Roughly 400 mg is three 240 ml filter coffees, or two large energy drinks plus a cola.
The tool computes your personal cutoff as bedtime minus 5 hours × log₂(drink mg ÷ your remaining budget), where the budget is 50 mg minus whatever your existing log already projects at bedtime. In practice a single 120 mg filter coffee on an otherwise clean day needs roughly six hours before sleep to fall under the 50 mg line.
In your browser's local storage only — the last 14 days are kept and older days are pruned automatically, with a 7-day bar showing recent totals. Nothing is uploaded. If caffeine is affecting your sleep, heart rate or anxiety, discuss it with a doctor rather than relying on this estimate.