16:8 Fasting Schedule Calculator

About this calculator

16:8 time-restricted eating compresses all daily calorie intake into an 8-hour window and fasts for the remaining 16 hours, making it the most widely studied schedule in the broader intermittent-fasting family that also includes 5:2 and alternate-day fasting. The approach was popularized by Martin Berkhan's “Leangains” protocol and has since been examined in circadian-biology research, including time-restricted-eating studies from Dr. Satchidananda Panda's lab at the Salk Institute, which link meal timing to metabolic markers independent of what is eaten.

Because the 16:8 window is defined relative to when someone wakes, works, or trains rather than a fixed clock time, people following it need to translate “16 hours fasted” into actual start and stop times for their own day — for example, a last meal at 8 PM means the eating window reopens at noon the next day.

This calculator takes your chosen start of eating (or end of fasting) and instantly lays out your full daily fasting and eating windows, so you can see exactly when your 16-hour fast begins and when your 8-hour eating window opens and closes.