Caffeine Crash Calculator
See how long your coffee really lingers — and the exact time to stop so it doesn't wreck your sleep.
How much caffeine?
mg
Still in your system at bedtime
72 mg
This will hurt your sleep
Last call for caffeine today
12:01 PM
to be under 50mg by bed
last drink+6h+12h
Estimate only. Caffeine's half-life averages ~5–6 hours but varies hugely with genetics, pregnancy, medication and smoking. The dashed line is the 50mg "sleep-safe" mark.