Calculate your fasting schedule
Your eating window, from a start time and a fasting pattern.
Try our other calculators
How the windows work
Each pattern names the fasting hours first and the eating hours second: 16:8 means 16 hours fasting and an 8-hour eating window, and so on down to 20:4, which leaves a single 4-hour window a day.
None of it is a fixed rule. Pick a start time that matches your actual schedule; a window that fights your normal mealtimes rarely lasts.
What it does and does not do
Fasting changes when you eat, not automatically how much: most of the evidence for weight loss comes from people naturally eating less inside a shorter window, not from any special metabolic effect of the fast itself.
It is not a fit for everyone, including anyone pregnant, with a history of disordered eating, or managing diabetes on medication that requires food alongside it. Check with a doctor first if any of that applies.
