16:8 fasting timer
16:8 means 16 hours fasting and 8 hours eating. A common window is noon to 8pm. This page is a free 16:8 timer in the browser — no app, no signup, not medical advice.
This URL is the 16:8 clock.
The timer on this page has 16:8 pre-selected. Use Start Fast when JavaScript is on.
The 16:8 chip is pre-selected here: sixteen hours on the ring, then eat in the next eight. 10am to 6pm is the same duration as noon to 8pm on a different clock. Fit the window to sleep and shared meals, not to a screenshot. Keeping a window in real life is that page.
Who 16:8 is for
People who already eat on a daily window — skip breakfast, or stop after dinner — and want a clock for that 16/8 split. It is not a multi-day fast. It is not OMAD.
If you wanted one meal a day, use the OMAD timer. If you only wanted elapsed time with no 16:8 target, use the online fasting timer.
For how to pick hours, read Choosing a starting window. Common fasting schedules compares daily windows without a ranking. What is intermittent fasting? is the definition.
The 8-hour side is still meals, not a prize binge: Eating in the window. Training beside a daily window: Exercise and fasting. What human TRE trials actually measured: Time-restricted eating in humans.
16:8 questions
What is 16:8?
16:8 means about 16 hours without calories and an 8-hour eating window. It is a daily time-restricted pattern, not a 48-hour fast and not one meal a day. See What is intermittent fasting?.
What is an example 16:8 window?
Noon to 8pm is a common example: last calories at 8pm, next meal at noon. 10am to 6pm or 12pm to 8pm are the same 16/8 split on a different clock. Fit the window to sleep and shared meals.
Can I drink water or black coffee on 16:8?
Water is the default during the 16 fasting hours. Black coffee or unsweetened tea are optional. Drinks with meaningful calories end a strict 16:8 window.
When does the eating window open?
After about 16 hours on this clock, the 8-hour eating window is when you eat. The timer is a clock, not a lock. End Fast when you eat, or sooner if you should stop.
I started the wrong preset. Am I stuck?
No. Use Change mode under End Fast. The start time stays; only the goal changes. If you meant Open or OMAD instead of 16:8, switch there. If you meant 16:8 and tapped another chip, switch back.
I forgot to start on time. Can I fix it?
Yes. While the clock is running, use Edit Start Time next to the started time. Set when you actually stopped eating. The elapsed hours jump to match. You cannot pick a time in the future.
Is a longer fast better than 16:8?
No. Longer is not automatically better. 16:8 is a daily window, not a ladder to 24h or 36h. Stay with the eating window you can keep, or stop if you should stop.
Is this medical advice?
No. This URL is a 16:8 browser timer. It cannot see your medicines or labs. If you are pregnant, under 18, underweight, or managing diabetes or an eating disorder, do not treat Start as clearance.
Do not start unsupervised if
You are pregnant or breastfeeding, under 18, underweight, or living with an eating disorder (now or in recovery). Diabetes, kidney disease, and medicines that lower blood sugar or blood pressure also move this out of “try a window” and into a conversation with a clinician who knows you.
End the fast if
- Dizziness on standing, confusion, fainting, chest pain, or severe weakness
- A tremor or dread that is not ordinary hunger
- You take glucose-lowering medicine and feel low
- Food distress shows up: panic, numbness, or a pull toward bingeing or purging
Fasting Library · Fasting Fundamentals · How to make fasting easier · Longer fasts · Very long fasts · Using the Clock · Everyday Fasting · Questions from the community · History of Fasting · Humans, Food & Feast–Famine · What Research Suggests