Common fasting schedules compared (16:8, 18:6, OMAD)

How to read the numbers

The first number is hours without food. The second number is hours when you eat. 14:10 is a shorter fast than 16:8. 18:6 is a shorter eating window than 16:8. OMAD means one meal a day. People sometimes write it as about 23:1. It is not 16:8 with a louder name.

Two people on 16:8 can eat at different times. Noon to 8 p.m. and 10 a.m. to 6 p.m. are both 16:8. The numbers say how long the fast is. You still choose when those hours sit in your day.

Food in the eating hours is still food. Black coffee and unsweetened tea are common in the fasting hours. A drink with calories usually ends a strict fast. What counts as ending a fast is in our article What usually ends a fast.

16:8: the common daily default

16:8 is the schedule most people mean when they say intermittent fasting. A common pattern is eating from noon to 8 p.m., or from 10 a.m. to 6 p.m. Fit it to sleep and shared meals.

Eight eating hours is enough for two or three ordinary meals, or two meals plus a snack. That is why many people can keep 16:8 longer than a tighter window.

16:8 is not required. If 16 hours wrecks your sleep or training, 14 hours is a complete plan. 16:8 is popular, which is not the same as best for you. The 16:8 fasting timer starts with 16:8 already chosen.

18:6: a shorter eating window

18:6 is 18 hours without food and 6 hours when you eat. Meals have to sit closer together. Some people like the simplicity. Others find it hard to eat enough, especially around training or family dinners.

Treat 18:6 as a possible next step after 16:8 already feels ordinary. It is not the “real” version of fasting. If you get there by skipping meals you needed, the schedule is too tight.

OMAD: one meal, higher demand

OMAD means one meal a day. That can make a day simple. It can also make it hard to get enough protein, vitamins, and energy. Shared meals become all-or-nothing.

It is a hard first try for most people, and a poor default if you are still finding 12 to 16 hours, or if you use less food as punishment. If you try it, pick a stop date rather than treating it as a badge.

On this timer, OMAD is about 23 hours. That is a setting, not a recommendation that you should live there. The OMAD fasting timer starts with that button already chosen.

12:12 and 14:10

12:12 is often dinner to breakfast: finish dinner, eat breakfast about twelve hours later. 14:10 is a bit longer. Both are complete plans. They are not leftovers for beginners.

These hours are usually the right place to start, and a valid place to stay. If you have not picked hours yet, start with Choosing a starting window.

Daily windows vs 24-hour and multi-day fasts

A daily window (12:12 through OMAD) repeats most days. A 24-hour, 36-hour, or 48-hour fast is one long stretch. Water, risk, and how you eat after are not the same.

A 48-hour fast is not two 16:8 days. You do not eat in the middle. If you already mean more than a day, start with Before a longer fast.

Choosing without ranking “best”

Pick the shortest window that still does the job you want — simpler evenings, less late-night snacking, curiosity — and that you can keep on a normal week.

Medicines, diabetes, pregnancy, a history of disordered eating, night shifts, and hard training can make a popular ratio a bad idea. The useful schedule is one you can shorten or drop. See Who should be careful with fasting if that list includes you.

Night shifts, travel, and a late dinner: read Keeping a window in real life for more information.

On this timer, 16:8, 18:6, OMAD, Custom, and Open are hour buttons, not a ranking. Read Presets on this clock for how those buttons work. Open the [online fasting timer](/) if you already have a plan.