Fasting Tracker

Free tool

Intermittent fasting calculator

Enter when you last ate and your plan, and see when you can eat again, when your eating window closes and the stages on the way

When can I eat?

With 16:8, if you finished eating at 8:00 p.m., you can eat again at 12:00 p.m. the next day, and your eating window closes at 8:00 p.m.

Calculated in your browser. Nothing you enter is sent anywhere.

How the calculator works

Each plan is named after its hours: 16:8 means a 16-hour fast and an 8-hour eating window. The calculator adds the fasting hours to the time you finished eating to find when your fast ends, then adds the eating hours to find when your window closes and the next fast begins. It works in your device's time zone, and nothing you enter leaves your browser.

Fasting Tracker's eight plans. The first four are free; Pro adds the longer ones and custom plans from 12 to 72 hours.
PlanFastEatLevelStage your fast reachesIn the app
13:11 Circadian13 h11 hBeginnerFuel SwitchFree
14:10 Gentle Start14 h10 hBeginnerFuel SwitchFree
16:8 Leangains16 h8 hIntermediateFat BurningFree
18:6 Fat Burner18 h6 hIntermediateFat BurningFree
20:4 Warrior20 h4 hAdvancedFat BurningPro
OMAD, One Meal a Day23 h1 hAdvancedFat BurningPro
24 hours, Full Day24 hNone that dayExpertKetosisPro
36 hours, Monk Fast36 hNone for a day and a halfExpertAutophagyPro

Tips for your first fasts

  1. Start the clock when you finish your last bite, not when you sit down.
  2. Drink water through the fast. Black coffee and plain tea are fine too.
  3. Break your fast with a meal built around protein, vegetables and fibre 1.
  4. Keep your times the same each day: your hunger rhythm adapts within days to weeks 2,3.

Sources

  1. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S-1329S. doi.org/10.3945/ajcn.114.084038
  2. Ravussin E, Beyl RA, Poggiogalle E, et al. Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity (Silver Spring). 2019;27(8):1244-1254. doi.org/10.1002/oby.22518
  3. Natalucci G, Riedl S, Gleiss A, et al. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. Eur J Endocrinol. 2005;152(6):845-50. doi.org/10.1530/eje.1.01919
  4. Grajower MM, Horne BD. Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients. 2019;11(4):873. doi.org/10.3390/nu11040873

A note on health

Fasting Tracker is designed for general wellness and is not a medical device. Fasting is not right for everyone. If you are pregnant, diabetic, have a history of eating disorders or take medication, talk to your doctor first, and before any extended fast.