Caffeine Cutoff Calculator: Last Coffee Before Bed
Enter your bedtime and the caffeine dose. The calculator gives the latest safe time to take it and shows how much caffeine is still in your body at bedtime.
Based on Gardiner et al. (2023, Sleep Medicine Reviews): a standard coffee (about 107 mg) should be taken at least 8.8 hours before bed and a typical pre-workout (about 217 mg) at least 13.2 hours before bed. The decay curve assumes a 5-hour half-life, which varies widely between people. Pregnancy and some medicines slow caffeine clearance a lot.
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