Caffeine Half-Life Calculator
See how much caffeine from your matcha is still in your system at bedtime, with a 12-hour decay curve based on caffeine's roughly five-hour half-life.
By WhiskMetrics Editorial Team · Last reviewed
Usucha (2 g) ≈ 70 · Latte (3 g) ≈ 105 · Koicha (4 g) ≈ 140 — estimates
Typical adult ≈ 5 h (range ~1.5–9.5 h); longer in pregnancy or with oral contraceptives
Caffeine from matcha clears like caffeine from any drink: about half is gone every ~5 hours. L-theanine does not speed that up, so an afternoon cutoff still matters.
How to estimate caffeine at bedtime
- 1
Enter your dose
Enter the caffeine in your drink, about 70 mg for a 2 g bowl of usucha.
- 2
Set the times
Enter when you drank it and when you plan to sleep.
- 3
Adjust half-life
Keep the 5-hour default or move it if you are pregnant, take oral contraceptives, or know you are sensitive.
- 4
Read the curve
Check the milligrams remaining at bedtime and shift your cutoff time if needed.
Other versions
How long does caffeine stay in your system?
Caffeine's half-life, the time it takes your body to clear half of a dose, averages about five hours in healthy adults, according to the Institute of Medicine's review of caffeine pharmacology. Individual values range widely, from roughly 1.5 to 9.5 hours. The calculator uses that average as a default, and you can adjust it.The math is simple exponential decay: remaining caffeine = dose × 0.5 ^ (hours ÷ half-life). A 70 mg serving of matcha at 2 pm leaves about 20 mg at 11 pm, nine hours later. A 105 mg latte at 4 pm leaves about 43 mg at 10:30 pm.
Typical matcha doses
Matcha is about 19 to 44 mg of caffeine per gram, so as rough estimates:- Usucha, 2 g: about 70 mg (range 38–89 mg)
- Matcha latte, 3 g: about 90–105 mg (range 57–133 mg)
- Koicha, 4 g: about 140 mg (range 76–178 mg)
What changes your half-life?
The IOM review lists several factors that change caffeine clearance:- Pregnancy slows it substantially, especially later in pregnancy
- Oral contraceptives can roughly double the half-life
- Smoking speeds clearance
- Liver disease and some medications can slow it markedly
Does L-theanine cancel the caffeine?
No. Matcha's L-theanine may smooth how caffeine feels, but it does not remove caffeine or speed its elimination. If an afternoon latte keeps you up, the caffeine is still there, even if you don't feel jittery.Reading the result
- Under about 25 mg at bedtime: unlikely to disturb most people
- 25 to 50 mg: some sensitive sleepers may notice lighter sleep
- Over 50 mg: comparable to drinking half a cup of coffee before bed
Practical cutoffs for matcha drinkers
With a five-hour half-life, it takes roughly ten hours to get down to a quarter of a dose. For an 11 pm bedtime, finishing your last usucha by early afternoon keeps the bedtime residue near or below 20 mg. If you love an afternoon latte, a smaller 2 g serving or a lighter strength helps.Sources
Frequently asked questions
What is the half-life of caffeine?
About five hours on average in healthy adults, with a wide individual range of roughly 1.5 to 9.5 hours, according to the Institute of Medicine.
How long before bed should I stop drinking matcha?
Many people do well with a cutoff 8 to 10 hours before bed. With a five-hour half-life, a 70 mg bowl of usucha drops to about 20 mg after nine hours.
Does matcha caffeine wear off faster than coffee?
No. Caffeine clears at the same rate regardless of source. L-theanine may change how it feels but not how long it lasts.
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