Daily Calorie Calculator
How This Calculator Works
Two-step. Mifflin-St Jeor for BMR, multiplied by activity factor for TDEE, plus or minus the goal-based deficit or surplus. The 500 kcal/day rule for 1 lb/week comes from the classic 3,500 kcal-per-pound-of-fat approximation.
BMR = Mifflin-St Jeor (sex, age, height, weight)
TDEE = BMR × activity multiplier
Daily target = TDEE + goal adjustment
Goal adjustments:
Lose 1 lb/week −500 kcal/day
Lose 0.5 lb/week −250 kcal/day
Maintain 0
Gain 0.5 lb/week +250 kcal/day
Gain 1 lb/week +500 kcal/dayCitation: Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." American Journal of Clinical Nutrition, 1990;51(2):241–247. The 3,500 kcal-per-pound rule is an approximation; see Hall KD, et al., "Quantification of the effect of energy imbalance on bodyweight," The Lancet, 2011;378(9793):826–837 for a more dynamic model.
Using This Number
Eat at the recommendation for 3–4 weeks before adjusting. Real bodies don't drop weight in straight lines — water, glycogen, and digestive content swing pounds daily. Track weekly averages, not single weigh-ins. If your 4-week trend doesn't match the goal, adjust by 100–200 kcal. That's it. No need to overthink it.
Limitations
The 3,500 kcal-per-pound rule is an approximation that overestimates long-term loss because metabolism adapts as you get smaller. Hall et al.'s dynamic model (2011) describes this more accurately. For most people, the simple version is close enough for the first few months — just expect the rate to slow and recalculate every 5–10 lb.
Lower bounds: eating below ~1,200 kcal/day for women or ~1,500 kcal/day for men is generally not recommended without clinical supervision. If your math pushes the recommendation that low, add activity rather than cutting more.
Frequently Asked Questions
How do I lose weight with this calculator?
Pick a goal — losing 1 lb/week creates a 500 kcal/day deficit (3,500 kcal/week, the rough kcal-per-lb rule). Losing 0.5 lb/week is a 250 kcal/day deficit. Eat at the recommended number consistently and track results over 3–4 weeks. If the scale isn't moving, adjust by 100–200 kcal.
Is 1 lb per week a safe rate of weight loss?
For most healthy adults, yes. A 0.5 to 1 lb/week loss is the range most clinicians recommend — fast enough to see results, slow enough to preserve muscle and metabolic health. Faster loss (more than 1% of body weight per week) tends to come with more muscle loss and faster metabolic adaptation.
Why doesn't my weight drop linearly?
Because real bodies are messy. Glycogen and water swing daily by several pounds. Bowel content, sodium, hormones (especially around menstrual cycles) all add noise. Track weekly averages, not daily numbers. If your 4-week trend is flat at the calculator's recommendation, your real TDEE is probably lower than estimated — drop by 100–200 kcal.
Should I go below 1,200 kcal (women) or 1,500 kcal (men)?
Generally no, not without clinical guidance. These are the rough lower limits where most adults can still meet their nutrient needs from food. Below them, micronutrient gaps become hard to avoid, and metabolic adaptation kicks in faster. If your TDEE is so low that 1,200 kcal feels aggressive, consider adding activity instead of cutting more.
What activity level should I pick?
Be honest. Sedentary = desk job, no exercise. Lightly active = 1–3 light workouts/week or job on your feet. Moderately active = 3–5 workouts/week. Very active = hard exercise 6–7 days/week. Extra active = physical job plus daily training (rare). Most people overestimate by one tier — when in doubt, pick the lower one.
Can I really gain 1 lb of muscle per week?
Almost certainly not, beyond the first few months of training. Realistic muscle gain rates: beginners maybe 1–2 lb/month, intermediates 0.5–1 lb/month, advanced lifters far less. The 'gain 1 lb/week' goal will mostly produce fat gain. For lean muscle gain, 'gain 0.5 lb/week' is more realistic — and even that is generous after the beginner phase.
Why is my recommended calorie target lower than I expected?
Likely one of three reasons: you've overestimated your activity level, you're shorter or older than the population average, or you're going for an aggressive goal. The Mifflin-St Jeor equation is conservative and accurate within about 10%, so the number is usually correct — just maybe lower than what you've heard online.
Should I track every calorie?
Tracking accurately for the first few weeks is a useful learning experience — most people are surprised at how much (or how little) they're really eating. After that, a lot of people maintain by eating mostly the same meals on rotation and only tracking new or unfamiliar meals. Whatever's sustainable for you long-term is what works.