Caffeine cut off

Caffeine from an afternoon coffee can still affect you at bedtime. Find the latest time for your last cup.

Your details

Bedtime
Caffeine in the drink
Caffeine half-life
Most you want left at bedtime
Planned last coffee (optional, to check it)

A mug of filter coffee is about 140 mg, instant 100 mg, tea 75 mg. EFSA puts the average half-life at about 4 hours (2 to 8 is normal).

Bed at 23:00, a 140 mg drink

17:00

your last caffeine of the day

  • Planning a coffee?pick its time below to check it against your cut off
  • Hours before bed6 h (the NHS 6 hour rule)
  • Left at bedtime with your half life of 4.0 h49 mg
  • If you clear caffeine fast (2 h half life)18 mg left
  • If you clear it slowly (8 h half life)83 mg left

Caffeine halves in the body roughly every 4 hours, but anywhere from 2 to 8 is normal, and pregnancy and some medicines slow it a lot. EFSA says 100 mg close to bedtime can disturb sleep in some adults. If you are a slow clearer, an earlier cut off may suit you better.

See your GP if changing your sleep habits has not helped, you have had trouble sleeping for months, or it is making it hard to cope. If you feel sleepy while driving, stop somewhere safe.

Check a planned coffee

Is a 4pm coffee too late?

Pick the time of the coffee you have in mind and the result tells you how much time you have to spare before your cut off, or how far past it you are, and how many milligrams would still be in your body at bedtime. A 140 mg coffee at 16:00 with a 4 hour half life leaves about 44 mg at 23:00. Bedtimes after midnight are included for late shifts and weekends.

The working

Bed at 23:00, a 140 mg filter coffee

With a 4 hour half-life, 140 mg needs about 6 hours to fall to 50 mg (140, then 70 after 4 hours, then 49.5 after 6). The NHS rule is also no caffeine in the 6 hours before bed, so the cut off is 17:00. A fast clearer (2 hour half-life) would have about 18 mg left at bedtime; a slow one (8 hours) about 83 mg, close to the 100 mg EFSA says can disturb sleep.

Half-life

Why it varies

Half-life is the time your body takes to clear half of the caffeine. EFSA says it averages about 4 hours in healthy adults but ranges from 2 to 8, and it is longer in pregnancy and with some medicines. If you sleep badly even with a 6 hour gap, try putting 6 or 8 in the half-life box.

Better sleep

Beyond the coffee

  • Remember tea, cola, energy drinks and dark chocolate count too
  • Keep a regular bedtime and wake time
  • No alcohol or smoking in the 6 hours before bed either
  • Avoid exercise in the 4 hours before bed, as the NHS suggests

Read with care

What this cannot tell you

  • Know your half-lifeIt changes with genes, pregnancy, smoking and medicines.
  • Fix every sleep problemStress, light, noise and health all play a part.
  • Replace your GPLong term sleep problems are worth a proper chat.

Questions

Common questions

Is my afternoon coffee too late?

Pick its time in the planned coffee box. If it lands after your cut off, a decaf, a short walk in daylight or a few minutes of slow breathing gives a lift without the late night cost.

What time should I stop drinking coffee?

The NHS suggests at least 6 hours before bed, so about 5pm for an 11pm bedtime. Slow clearers may need longer.

What is caffeine's half-life?

About 4 hours on average in healthy adults, with a normal range of 2 to 8 hours, according to EFSA.

Does decaf after dinner matter?

Decaf has only a little caffeine, so it is a good evening swap for most people.

Can caffeine affect sleep even if I fall asleep fine?

Yes. EFSA notes 100 mg close to bedtime can change sleep length and patterns in some adults, even if you drop off easily.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

If sleep is a struggle

See your GP if changing your habits has not helped, you have had trouble sleeping for months, or it is making it hard to cope. If you feel sleepy while driving, stop somewhere safe.

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