About Calculate Fasting
The free, real-time intermittent fasting tracker that tells you exactly what your body is doing — hour by hour.
What is Calculate Fasting?
Calculate Fasting is a free, no-login intermittent fasting tracker that tells you exactly what your body is doing right now based on when you last ate. Enter your last meal time — or tap a single button the moment you finish eating — and the tracker calculates your fasting hours in real time, shows you a live health milestone timeline, and explains what's happening inside your body at every stage: fat burning, ketosis, autophagy, and beyond.
Why we built this
Most fasting apps require an account, a subscription, or a download. We built Calculate Fasting because fasting is simple — and your tracker should be too. No app store. No login. No monthly fee. Just open the site, log your meal, and know exactly where you are in your fast. Your data never leaves your device.
What makes it different
Real-time body status
Know whether you're digesting, burning fat, in ketosis, or in autophagy — explained in plain language, updated every minute.
No account needed
Everything is stored locally on your device. Nothing is sent to any server. Your fasting data is 100% private.
Built for every protocol
Whether you do 16:8, 18:6, 20:4, OMAD, or extended fasting — Calculate Fasting tracks it and shows your progress toward your goal.
Who uses Calculate Fasting?
People who want to know if they're in ketosis yet. Beginners starting their first 16:8 window. Experienced fasters tracking autophagy. Anyone who has ever glanced at the clock and wondered, "how many hours have I been fasting?" Calculate Fasting was built for all of them — and for you. It doesn't matter whether this is day one of your very first fast or your thousandth clean 18:6. The tracker meets you exactly where you are and tells you what's happening inside, in language anyone can understand.
That's really the heart of it: fasting should feel empowering, not confusing. Whether you're chasing fat loss, cellular renewal, better focus, or simply a calmer relationship with food, knowing where you stand in your fast makes the whole thing easier to stick with. We built Calculate Fasting to be the simple, honest, always-free companion that's in your corner — one tap, every hour, on whatever device you already have.