Caffeine calculator

How much caffeine is still in you

Pick what you drank and when. See what is left at bedtime, and how late the same drink still lets you sleep.

Free on the App StoreGet Cira for iPhone Try the calculator
  • No account
  • Nothing leaves your iPhone
  • Free reminder before your last cup

Last drink before bed

Half-life 5.7 h · peak at 45 min · sleep threshold 40 mg
At bedtime
—mg
Below 40 mg at
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Latest for tonight
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Cira runs this on every drink you log and tells you the hour to stop. Get Cira free →
Caffeine in drinks

How much is in your cup

Espresso
64mg

1 oz shot (30 ml), clears in 4 hours

Filter coffee
96mg

8 oz cup (240 ml), clears in 7 and a half hours

Flat white
125mg

5.4 oz cup (160 ml), clears in 9 and a half hours

Monster
160mg

16.9 oz can (500 ml), clears in 11 and a half hours

Matcha
67mg

8 oz cup (240 ml), clears in 4 and a half hours

Red Bull
80mg

8.4 oz can (250 ml), clears in 6 hours

All 36 drinks, with the numbers →

Look it up

By dose, by bedtime, side by side

How long a dose lasts

From 50 mg to 600 mg, hour by hour

Cutoff by bedtime

The last coffee for a bedtime from 9 pm to 1 am

Drink against drink

Red Bull or Monster, matcha or coffee, side by side

Guides

Questions people ask

When should you stop drinking coffee before bed?For a mug of filter coffee and an 11 pm bedtime, about half past three. Here is how to work out your own cutoff from the cup you actually drink.How long does caffeine last?Caffeine peaks 45 minutes after you drink it, halves every 5.7 hours, and is effectively gone in about a day. What that means hour by hour.Caffeine half-life, with the actual numbersAbout 5 to 6 hours for a healthy adult, 1.5 to 9.5 from person to person, up to 15 in pregnancy. The formula, the table and what changes it.How much caffeine is too much in a day?400 mg is the healthy adult limit, 200 mg in pregnancy, 200 mg in one sitting. What those numbers look like in real drinks.Espresso or filter coffee: which has more caffeine?Per millilitre espresso wins by five to one. Per cup filter coffee wins by half. Both facts are true and the cup is the one that matters.I fall asleep fine after coffee. Is it still hurting my sleep?Almost certainly yes. Caffeine six hours before bed cuts deep sleep measurably in people who report sleeping normally.
The app

Cira does this all day

The calculator answers one drink at a time. Cira keeps the whole day in view, on your iPhone, in a Home Screen widget and on the Lock Screen.

  1. Log a drink in one tap36 drinks built in, from espresso to pre-workout.
  2. Watch your own curveTuned to how fast your body clears caffeine.
  3. Know your last cupA reminder arrives before the one that would cost you sleep.
Free on the App StoreGet Cira for iPhone
CiraCaffeine tracker for iPhone Get