How much caffeine is safe?
For most healthy adults, up to about 400 mg of caffeine a day is considered safe — roughly four 8 oz cups of brewed coffee. Going over that regularly can bring on jitters, a racing heart, and trouble sleeping. If you're pregnant, the usual advice is to stay under about 200 mg a day.
Everyone processes caffeine a little differently, so the right amount for you may be lower. Use the numbers above as a starting point and pay attention to how you feel.
Caffeine & sleep
Caffeine has a half-life of roughly 5–6 hours, which means half of it is still in your body that long after your last sip. To protect your sleep, many people set a cutoff time and have their last caffeine at least 8 hours before bed.
Typical caffeine content
- Brewed coffee (8 oz): ~95 mg
- Espresso (1 shot): ~63 mg
- Black tea (8 oz): ~47 mg
- Energy drink (8 oz): ~80 mg
- Cola (12 oz): ~34 mg
