How accurate are TDEE calculators?

Within 10% for most people. Real-world variation comes from differences in NEAT (non-exercise activity), thermogenesis, and recovery costs from training.

Why is my TDEE not matching my scale?

TDEE is an estimate. If you're not losing on a 500 kcal deficit after 4 weeks, drop another 200. If you're gaining on a "maintenance" target, bump activity multiplier down a tier.

Should I use BMR or TDEE for weight loss?

Use TDEE — eating only at BMR is far below your true expenditure and almost always too aggressive. The Academy of Nutrition and Dietetics suggests deficits of 500–750 kcal/day below TDEE for sustainable loss of 0.5–1 kg per week.

Does TDEE change as I lose weight?

Yes — both BMR and the activity multiplier scale down as weight drops. Recompute every 4–6 kg of weight change, or whenever a 4-week trend stalls at the same deficit.

Which BMR formula should I use — Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle?

Mifflin-St Jeor (default) is the best general-purpose BMR formula and what most clinicians use; it averages within 10% of measured BMR for typical adults. Harris-Benedict revised (1984) is the older standard and runs about 5% higher — listed for reference. Katch-McArdle is the most accurate IF you know your body fat % (e.g. from a DEXA scan or bioimpedance reading), because it uses lean body mass instead of total weight — particularly important for athletes, bodybuilders, and very lean people where Mifflin overestimates BMR by ignoring their muscle-to-fat ratio. Enter your body fat % above to auto-switch to Katch-McArdle.

How do I measure my body fat % accurately?

Best: DEXA scan (~$50-150) — clinical gold standard, ±1-2% accuracy. Good: BodPod (~$50), Bioelectrical Impedance Analysis (BIA) scales (Tanita, Inbody — ~$50-300 device, ±3-5%). OK: Navy tape method (free, ±4-6% — try our body-fat-calculator). Avoid: visual estimates and consumer-grade BIA scales, which can be off by 5-10%. If you can not measure accurately, leave the field blank and use Mifflin-St Jeor.

Calorie Calculator (TDEE) — embedded

Result

TDEE (maintain weight)

2,633 kcal/day

Using Mifflin-St Jeor BMR × 1.55 activity

BMR (rest only) — Mifflin-St Jeorcalories burned doing nothing — used to compute your TDEE above1,699 kcal/day
— BMR formula comparison —
Mifflin-St Jeor (1990)Most accurate for general population1,699 kcal/day
Harris-Benedict revised (1984)Older formula; runs ~5% higher than Mifflin-St Jeor1,763 kcal/day
Katch-McArdle (1973)Requires body fat % for lean-body-mass calculation. Most accurate for athletes and lean individuals.Enter body fat % to compute
Activity multiplier× 1.55
Mild weight loss (−250 kcal/day)~0.5 lb / week2,383 kcal/day
Weight loss (−500 kcal/day)~1 lb / week2,133 kcal/day
Lean bulk (+250 kcal/day)~0.5 lb / week2,883 kcal/day
Bulk (+500 kcal/day)~1 lb / week3,133 kcal/day

BMR (Mifflin-St Jeor)

rest-only baseline — primary formula used

1,699 kcal/day

TDEE (your activity)

maintenance

2,633 kcal/day

Cut: −500 kcal/day

~1 lb / week loss

2,133 kcal/day

Aggressive cut: −750 kcal/day

~1.5 lb / week (only if obese)

1,883 kcal/day

Lean bulk: +250 kcal/day

~0.5 lb / week gain

2,883 kcal/day

Sedentary multiplier ×1.2

desk job baseline

2,039 kcal/day

Very active multiplier ×1.725

6-7 days hard exercise

2,930 kcal/day

Source: Mifflin-St Jeor BMR equation (Mifflin et al., Am J Clin Nutr 1990)

Not medical advice — TDEE is a population estimate (±10%). Real burn varies with NEAT, thermogenesis, and recovery costs. Treat the number as a 7-day average target and adjust based on actual scale change after 2-4 weeks.

How to use this calculator

Enter your sex, age, weight, and height.
Pick activity level honestly — most people overestimate (use Sedentary if you sit at a desk, even with daily walks).
Use the maintain figure as your daily target, then adjust up or down for your goal.

About this tool

Total Daily Energy Expenditure (TDEE) is what you burn in 24 hours including activity — the calorie target for maintaining your current weight. Calculated by multiplying your Basal Metabolic Rate (BMR — calories burned at complete rest) by an activity factor. The Mifflin-St Jeor equation (used here) is the most accurate of the common BMR formulas for most adults. Real-world calorie burn varies day to day; treat the number as a 7-day average target, not a daily ceiling. To lose weight: eat 250–500 kcal/day below TDEE. To gain: 250–500 above.

How it works — the formula

Mifflin-St Jeor BMR:
  Men:   10·weight(kg) + 6.25·height(cm) − 5·age + 5
  Women: 10·weight(kg) + 6.25·height(cm) − 5·age − 161
TDEE = BMR × activity factor (1.2 sedentary → 1.9 very active)

Mifflin-St Jeor (1990) replaced the older Harris-Benedict equation as the most accurate BMR estimate for healthy non-obese adults; it tracks indirect-calorimetry measurements within ~5%. The activity factor scales BMR up to total daily expenditure, including non-exercise thermogenesis (NEAT), digestion (TEF), and exercise. Multipliers come from the FAO/WHO/UNU Human Energy Requirements report.

Sources: Mifflin MD et al. — A new predictive equation for resting energy expenditure in healthy individuals (Am J Clin Nutr 51(2) 1990) · FAO/WHO/UNU — Human Energy Requirements (Rome, 2004) · Academy of Nutrition and Dietetics — Position: Interventions for the Treatment of Overweight and Obesity in Adults (J Acad Nutr Diet 2016)

Worked examples

Example 1

30-year-old male, moderate activity

Inputs:: sex = male, age = 30, weight = 75 kg, height = 178 cm, activity = moderate (×1.55)
Output:: BMR ≈ 1,718 kcal/day; TDEE ≈ 2,663 kcal/day

Example 2

40-year-old woman, sedentary desk job

Inputs:: sex = female, age = 40, weight = 65 kg, height = 165 cm, activity = sedentary (×1.2)
Output:: BMR ≈ 1,320 kcal/day; TDEE ≈ 1,584 kcal/day

Example 3

Weight-loss target

Inputs:: TDEE = 2,500 kcal/day, deficit = 500
Output:: Cut target ≈ 2,000 kcal/day → ~0.45 kg / 1 lb loss per week

What TDEE means

Total Daily Energy Expenditure (TDEE) is the number of calories your body burns in a full 24 hours to sustain all its functions and activities. It combines four components: BMR (basal metabolic rate — the ~60-75%% burned at complete rest for organ function), EAT (exercise activity thermogenesis), NEAT (non-exercise activity thermogenesis — walking, fidgeting, standing), and TEF (thermic effect of food, ~10%% of calories consumed).

This calculator estimates TDEE from the Mifflin-St Jeor BMR formula multiplied by a physical activity factor. The activity factor is the largest source of estimation error — most people overestimate their activity level, resulting in TDEE estimates 100-300 kcal higher than reality.

How to actually use TDEE

For weight maintenance: eat approximately your TDEE each day. Weight fluctuates 2-5 lb daily from water and gut content even at perfect energy balance — track weight over 2-4 week windows, not day-to-day.

For weight loss: subtract 500 kcal/day from TDEE for approximately 1 lb/week fat loss (a 3,500 kcal weekly deficit). Deficits above 750-1,000 kcal/day risk muscle loss, metabolic adaptation, and unsustainability.

For muscle building: add 250-500 kcal/day above TDEE, combined with progressive resistance training and adequate protein (0.7-1.0 g/lb of lean body mass). Faster surpluses produce more fat gain per pound of muscle. Realistic muscle-building rate: 0.5-2 lb/mo for men, 0.25-1 lb/mo for women.

Why the calculator is only a starting point

TDEE formulas capture only about 70-80%% of variance in actual measured energy expenditure. Individual metabolic variation of ±200-300 kcal/day is normal, driven by mitochondrial efficiency differences, thyroid function, gut microbiome, and adaptive thermogenesis responses to prior diet history.

The right approach: use the calculator to get a starting estimate, eat at that level for 2-4 weeks tracking weight carefully, then adjust up or down based on actual weight trend. If you gain weight at the calculated "maintenance" level, your actual TDEE is lower — reduce intake by 100-200 kcal and retest. If you lose weight, actual TDEE is higher.

The macronutrient split debate

Once calorie target is set, macronutrient composition (protein / carb / fat split) has modest but real effects on body composition, satiety, and adherence.

Protein is the most-established macro to prioritise. Higher protein (0.7-1.0 g/lb of lean body mass, or 25-35%% of calories) preserves muscle during weight loss, increases satiety, and has higher TEF (~20-30%% vs ~5-10%% for carbs and ~3%% for fat). Almost all successful weight-loss protocols include adequate protein.

Carbs vs fat split is more individual. Endurance athletes benefit from higher carbs (55-65%%); people with insulin resistance often do better on lower carbs (25-35%%); most sedentary or moderately-active people work well with anything from 30-50%% carbs. The best split is one you can sustain.

Common calorie-tracking mistakes

Under-reporting food intake by 20-40%% is documented across many food-tracking studies. Common under-reporters: cooking oils and dressings, sauces and marinades, portion sizes eyeballed rather than weighed, alcoholic drinks, small snacks, "just tastes" while cooking.

Over-reporting exercise burn is similarly common. Fitness trackers overestimate calorie burn by 25-90%% depending on activity. Machine displays at the gym typically overestimate by 25-50%%.

The combination — under-reporting intake and over-reporting output — produces an apparent 300-600 kcal/day gap that consistently prevents weight loss. If your calculated deficit is not producing weight loss after 3-4 weeks, the most likely cause is measurement error, not "broken metabolism".

Limitations

BMR equations are calibrated on healthy adults aged 19–78; pregnancy, lactation, hyperthyroidism, and sarcopenia all shift the answer.
Activity multipliers assume honest self-assessment — most people overestimate by one tier.
TDEE drops as you lose weight; the same multiplier applied to a smaller body burns fewer calories.
NEAT can vary day to day by 300–800 kcal in the same individual — never treat the daily target as exact.

Calorie targets are starting points, not prescriptions. Adjust based on 2–4 weeks of actual weight trend. This calculator does not provide medical or dietetic advice — consult a registered dietitian or physician for clinical needs.

Frequently asked

BMR is just rest. Walking, fidgeting, digestion (TEF), and exercise all add to it. The activity multiplier captures that — without it, you'd under-eat by 30–80%.