Intermittent fasting from 8 AM to 4 PM: your 16:8 day

    Stop eating at 8 PM on 16:8 and the window opened at noon. Pick a protocol and the time your last meal ends to get the eating window, meal times, the next opening and a check on your workout and bedtime.

    Eating from 8:00 AM to 4:00 PM is the 16:8 pattern: 8 hours to eat, then 16 hours of fasting until the window opens again at 8:00 AM the next day. So if your last meal is finished at 4:00 PM, you can eat again at 8:00 AM. Split into three meals for maintaining weight, the day runs 8:00 AM, 12:00 PM and 3:30 PM, with the fast starting at 4:00 PM. The calculator below is set to 16:8, a last meal at 4:00 PM and the maintain goal; pick another goal, add a workout time or your bedtime, or move the last meal, and press Calculate.

    Parameters

    Enter data for calculations

    Hours of fasting : hours of eating

    Sets the number of meals

    Form progress0 / 2 fields

    💡 Fill in all required fields to unlock the calculate button

    Your eating window, worked back from the last meal

    Finish dinner at 8:00 PM on a 16:8 schedule and the window opened at 12:00 PM; the fast then runs to 12:00 PM the next day. That is the whole trick of time-restricted eating, and also where most plans go wrong: people pick a start time they like and only later notice the window closes in the middle of family dinner. This intermittent fasting calculator starts from the meal you actually want to keep, the last one, and works backwards to the opening time, the meal times in between and the moment the next window opens. It covers 14:10, 16:8, 18:6, 20:4, one meal a day and the 5:2 plan.

    What you choose

    • A protocol, from the gentle 14:10 to one meal a day
    • The time your last meal is finished
    • A goal, which sets how many meals fit
    • Optionally a workout time and a bedtime

    What comes back

    • Opening and closing time, in AM and PM
    • A meal timetable and a 24-hour bar
    • Whether the workout falls in the window or the fast
    • The latest last meal for a 3-hour gap before bed

    Setting up a fasting day in six choices

    1. Fasting protocol - 14:10, 16:8, 18:6, 20:4, OMAD (read as 23:1) or 5:2. The first number is the hours of fasting, the second the hours of eating.
    2. Last meal finished at - in half-hour steps around the clock. This is the closing time of the window. Not asked for 5:2, which counts days, not hours.
    3. Goal - losing weight, maintaining or gaining muscle. It only changes the suggested number of meals.
    4. Sex - asked for 5:2 only, because the fast-day limit is 500 calories for women and 600 for men.
    5. Workout start time - optional, or "No workout that day". The calculator says whether you train fed or fasted and, if fasted, which last-meal times would fix it.
    6. Bedtime - optional, from 8:00 PM to 2:00 AM, to check the gap between the last meal and sleep.

    How the window is placed on the clock

    Every daily protocol splits 24 hours into two blocks. The calculator takes your last-meal time as the end of the eating block and subtracts its length to find the start. The fast is the remaining block, so the next window opens exactly 24 hours after the previous one did.

    window opens = last meal - eating hours; next window = last meal + fasting hours
    14:10 with dinner at 7:00 PM. 7:00 PM minus 10 hours puts breakfast at 9:00 AM, the same example window Cleveland Clinic gives for 14:10.
    18:6 with a late finish at 9:00 PM. The window runs from 3:00 PM to 9:00 PM and the fast to 3:00 PM the next day.
    Night shift, last meal at 1:00 AM on 20:4. The window opens at 9:00 PM the evening before. The bar in the result draws a window that crosses midnight in two pieces, so it still reads correctly.

    Inside the window the meals are spread from the opening time to half an hour before the close: two meals when losing weight on 14:10 or 16:8, three when maintaining or gaining, one or two on the short 20:4 window, and one on OMAD. The split is a planning default, not a rule; what matters for the fast is that nothing with calories is eaten outside the window.

    Six protocols with dinner at 8:00 PM

    Each row is the calculator run with the last meal finished at 8:00 PM. The 5:2 row counts days instead of hours.

    Protocol Fast Eat Window Next window opens
    14:1014 h10 h10:00 AM to 8:00 PM10:00 AM
    16:816 h8 h12:00 PM to 8:00 PM12:00 PM
    18:618 h6 h2:00 PM to 8:00 PM2:00 PM
    20:420 h4 h4:00 PM to 8:00 PM4:00 PM
    OMAD (23:1)23 h1 h7:00 PM to 8:00 PM7:00 PM
    5:22 days5 days500 or 600 calories on fast daysat least 1 regular day between

    Cleveland Clinic calls 14:10 and 16:8 the safer bet for a first try at intermittent fasting, which is why the result adds a note on 18:6, 20:4 and OMAD.

    Training fed or fasted, and the gap before bed

    Cleveland Clinic advises exercising before or after a fast instead of in the middle of it, when you can still drink and refuel. Enter a workout time and the result tells you which side of the line it falls on. A 7:00 AM run on a 12:00 PM to 8:00 PM window is in the middle of the fast; on 16:8, any last-meal time from 7:00 AM to 3:00 PM would bring that run inside the window. Inside the window, the result counts how many planned meals come after the workout.

    The same source suggests starting the fast at least 3 hours before bedtime. Here is what that means for the latest last meal.

    Bedtime Last meal finished by 16:8 window then opens
    9:30 PM6:30 PM10:30 AM
    10:00 PM7:00 PM11:00 AM
    11:00 PM8:00 PM12:00 PM
    12:00 AM (midnight)9:00 PM1:00 PM
    1:00 AM10:00 PM2:00 PM

    The 5:2 plan and who should skip fasting

    On 5:2 you eat as usual five days a week and keep two days at 500 calories for women or 600 for men. Cleveland Clinic calls at least one regular day between the two fast days essential, so the result lists pairs such as Monday and Thursday, and advises eating your normal recommended amount on the other days rather than making up for the fast.

    Fasting is not for everyone. Cleveland Clinic names people who are pregnant or nursing, malnourished, with hypoglycemia or with certain chronic diseases, and children; with a history of an eating disorder it should happen only under medical supervision. If you take medication at set times, talk to your health care provider before you move them around a new eating window.

    Fasting window questions, briefly

    If I stop eating at 8 PM, when can I eat again?
    On 16:8 at 12:00 PM the next day, on 14:10 at 10:00 AM, on 18:6 at 2:00 PM. The table above lists all five daily protocols.
    How long should my eating window be?
    For a first try, 10 or 8 hours (14:10 or 16:8), the schedules Cleveland Clinic considers the safer start. Shorter windows make it harder to fit enough food and protein, which the result points out for muscle gain.
    Does black coffee break a fast?
    Cleveland Clinic lists water, carbonated water, black coffee and unsweetened tea as fine during the fast, and suggests limiting artificial sweeteners.
    How many calories do I eat on 5:2 fast days?
    500 for women and 600 for men, on two days that are not back to back.
    Does the calculator tell me how much weight I will lose?
    No. It plans the timing. Weight change depends on how much you eat in the window, which the calorie deficit calculator below can estimate.

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    See also

    Intermittent Fasting 1020: 16:8 Meal TimesIntermittent Fasting 1080: 16:8 Meal TimesIntermittent Fasting 1140: 16:8 Meal TimesIntermittent Fasting 1200: 16:8 Meal TimesIntermittent Fasting 1260: 16:8 Meal Times14:10 Intermittent Fasting Schedule: Eat 10:00 AM to 8:00 PM18:6 Intermittent Fasting Schedule: Eat 2:00 PM to 8:00 PM20:4 Intermittent Fasting Schedule: Eat 4:00 PM to 8:00 PMOMAD Schedule: One Meal a Day From 7:00 PM to 8:00 PM

    Calculator verified by the LiczGrupa.pl team

    Content, formulas and results have been reviewed for accuracy and relevance by our team of specialists.

    Natalia Skrzek

    Reviewed by: Natalia Skrzek

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