Free Tool
Free Calorie Calculator for Weight Loss
Find your maintenance calories and exactly how far below them to eat to lose fat at a pace you can live with. Built on the Mifflin-St Jeor equation and more than 20 years of real coaching. No email needed to see your numbers.
By Luke Thomas, NASM-CPT. Updated August 2026.
Calculate your daily calorie needs
This tool uses the Mifflin-St Jeor equation, the formula dietitians rely on. Be honest with the numbers and you will get an accurate result.
Your daily calorie needs
This is your maintenance level. Eat this much each day and your weight stays where it is.
For weight loss:
Food and movement do the work here, always. If cravings are what usually knock you off your number, LEAN is the one supplement I point people to while they hold a deficit. Read the full label and decide for yourself.
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Affiliate note: I may earn a commission at no extra cost to you. These statements have not been evaluated by the FDA. Not intended to diagnose, treat, cure, or prevent any disease.
Want the details first? See everything inside the free guide
Next step: split your calories into protein, carbs, and fat with the free macro calculator
How this calorie calculator works
The calculator uses the Mifflin-St Jeor equation, which estimates your basal metabolic rate, the calories your body burns at complete rest. Studies comparing the common formulas suggest Mifflin-St Jeor is the most reliable for most adults, which is why dietitians favor it. That resting number is then multiplied by an activity factor to estimate your total daily energy expenditure, the calories you actually burn in a normal day.
From there the math is simple. Eat at that number and your weight holds steady. Eat below it consistently and your body draws the difference from stored fat. A deficit of about 500 calories a day produces roughly one pound of loss per week for most people, though the exact pace varies from person to person.
What your three numbers mean
Maintenance
Your break-even point. This is what your body spends in a typical day. Weight loss math starts here, not at some universal 2,000 calories.
Mild deficit
About 250 calories under maintenance, roughly half a pound a week. The right pace if you have less than 15 pounds to lose, or you want to protect muscle and energy while you cut.
Moderate deficit
About 500 calories under maintenance, roughly a pound a week. The sweet spot for most women. Enough progress to stay motivated, not so steep that hunger takes over your evenings.
Five ways to make your calorie target actually work
1. Put protein first. Aim for 25 to 30 grams at each meal. Protein protects muscle while you lose and keeps you full on fewer calories.
2. Trust the weekly average, not the daily weigh-in. Your weight swings a few pounds day to day from water and food volume. Compare weekly averages before you change anything.
3. Count what you drink. Coffee drinks, juice, and wine can quietly claim 300 or more calories a day without making you any less hungry.
4. Leave room for real life. Keep 100 to 200 calories in reserve for the unplanned bite, the tasting spoon, the splash of oil. People who succeed plan for imperfection.
5. Recalculate as you lose. Your needs drop as your weight drops. Run the calculator again after every 10 pounds so your deficit stays honest.
Calorie calculator questions, answered
How many calories should I eat a day to lose weight?
Most women lose weight steadily eating 300 to 500 calories below their maintenance level, which often lands between 1,400 and 1,800 calories a day. Your exact number depends on your age, size, and activity, which is what the calculator above works out for you.
How accurate is this calorie calculator?
It uses the Mifflin-St Jeor equation, which research suggests is the most reliable of the standard formulas for estimating resting metabolism. It is still an estimate. Track your weight for two to three weeks, and if the scale is not moving, adjust your target by 100 to 200 calories.
Should I eat back the calories I burn exercising?
Usually no. Your activity level in the calculator already accounts for regular exercise. Eating back workout calories on top of that is one of the most common ways a deficit quietly disappears, especially since fitness trackers tend to overestimate what you burn.
Why am I not losing weight in a calorie deficit?
The most common reason is that the deficit only exists on paper. Untracked bites, cooking oils, dressings, and weekend meals add up faster than most people expect. Water retention can also hide fat loss on the scale for two or three weeks, especially around your cycle or after starting a new workout routine.
What is the lowest number of calories I should eat?
As a general guideline, women should not eat below about 1,200 calories a day without medical supervision. Very low targets tend to backfire: energy crashes, muscle loss, and rebound eating. If the calculator gives you an aggressive number below that line, choose the milder deficit instead. Slower is safer, and it lasts.
Do I have to count calories forever?
No. Counting works best as a short course in portion awareness, not a life sentence. Track carefully for a few weeks to calibrate your eye, then lean on habits: protein at every meal, vegetables for volume, and honest portions. That habit-first approach is exactly what the free 14-Day Reset teaches.
Your Next Step
Turn your number into results
The free 14-Day No-Gimmicks Weight-Loss Reset gives you one simple habit a day to put your calorie target to work. Same coach, same no-gimmicks approach.
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Questions? Learn how the three planning calculators work together in the Help Docs.
Practical health and fitness for women who want to feel strong at any age. Coached by Luke — NASM-certified (CPT, CES, PES) with 20+ years in the field.