Fasting calculator
Pick a protocol, tell us when you wake up, and see your exact fasting and eating windows.
Your first meal is placed ~2 hours after waking — an easy, sustainable default. General information, not medical advice.
A window is just the start
Kairo also sets your calorie target, tells you what to eat, and shows the smartest way to break your fast — personalized and explained.
Build my full plan — freeHow the fasting calculator works
Choose a protocol (16:8, 18:6, 20:4, or OMAD) and enter your usual wake time. The calculator places your first meal about two hours after waking, then maps your eating window and the fasting window that wraps around it. Ending your window a few hours before bed supports deeper sleep and steadier morning energy.
Which fasting schedule should I pick?
Beginners do best on 16:8; step up to 18:6, 20:4, or OMAD once your current window feels automatic. Read the complete beginner's guide for how to ease in.