Intermittent Fasting Calculator
Plan an intermittent-fasting schedule from common protocols, eating-window start time, wake time, and calories per meal window.
Last updated: 2026-03-27
Intermittent fasting calculator
Enter your values
Set the eating window first, then turn it into a practical meal-timing plan.
Eating Window
--
Enter a protocol, wake time, first meal time, calories, and meal count to build a fasting schedule.
Calculation History(0)
Example calculations
Tap an example to prefill the calculator with sample values.
Standard 16:8 workday
Wake at 6:30 AM, first meal at noon, two meals
A common time-restricted-eating rhythm that keeps the feeding window aligned with lunch and dinner.
Result: A fixed window makes the meal-timing side clear even before deciding what foods belong inside it.
18:6 training day
Later first meal with three smaller meals
Useful for people who prefer a tighter eating window but still want more than two feedings inside it.
Result: More meals can fit inside a shorter window if the schedule is tight and intentional.
OMAD experiment
Single evening meal after a long fasting period
A more aggressive schedule where meal size and daily sustainability deserve extra caution.
Result: Very narrow windows can look simple on paper but still require a more careful sustainability check.
How the fasting schedule is built
The calculator uses the chosen protocol to set the length of the eating window and fasting window. Your first meal time anchors the start of the eating window, and the window end time is calculated by adding the allowed feeding hours.
Daily calories are divided by the number of meals you plan to eat inside that window so the schedule is easier to use in practice. The tool is intentionally limited to timing and rough meal sizing rather than claiming that any fasting pattern is right for every person.
Intermittent fasting FAQs
This tool helps with timing and planning. Suitability still depends on your health context and how well the pattern fits your life.
What does this calculator actually tell me?
It schedules the timing side of intermittent fasting. You enter a protocol and your first meal time, and the calculator shows the eating window, fasting window, and calories per meal based on the daily intake you plan to eat.
Does intermittent fasting automatically cause weight loss?
Not automatically. Time-restricted eating can help some people reduce intake or improve consistency, but weight change still depends on total intake, adherence, food quality, sleep, stress, medication use, and individual response.
Who should talk to a clinician before trying fasting?
Anyone who is pregnant or breastfeeding, takes insulin or glucose-lowering medication, has a history of eating disorder, is underweight, or has a medical condition that makes long fasting periods risky should speak with a healthcare professional first.
Embed this calculator
Copy the code below to embed this calculator on your website or blog. It's free — no API key needed.
<iframe src="https://calc.mintloop.dev/embed/health/intermittent-fasting-calculator" width="100%" height="600" frameborder="0" title="Intermittent Fasting Calculator" loading="lazy"> </iframe>
Optional: auto-resize script
<script>
var CALC_HUB_ORIGIN = 'https://calc.mintloop.dev';
window.addEventListener('message', function(e) {
if (e.origin !== CALC_HUB_ORIGIN) return;
if (!e.data || e.data.type !== 'calc-hub-resize') return;
var frames = document.querySelectorAll('iframe[src*="calc.mintloop.dev"]');
frames.forEach(function(f) {
if (f.contentWindow === e.source) {
f.style.height = String(Math.max(0, Number(e.data.height) || 0)) + 'px';
}
});
});
</script> Related tools
Pair fasting-window timing with maintenance calories and hydration planning.
TDEE Calculator
Set a maintenance-calorie baseline before deciding how much to eat inside the fasting window.
Calorie Calculator
Turn maintenance calories into practical fat-loss or training-support targets.
Water Intake Calculator
Pair tighter eating windows with a hydration plan that still covers the full day.
Get more nutrition and recovery calculators
Join the Calc Hub newsletter for new calculators covering calories, hydration, recovery, and practical health planning.
Join the Calc Hub newsletterWas this calculator helpful?
Your feedback helps us improve future calculators.
Medical disclaimer
This calculator is for schedule planning only and does not determine whether intermittent fasting is safe or appropriate for you. Talk to a healthcare professional before using fasting if you are pregnant, breastfeeding, on diabetes medication, underweight, or have a medical condition that affects eating safety.
If fasting causes dizziness, disordered eating thoughts, persistent fatigue, or training performance problems, stop and seek clinical guidance.