Calorie & TDEE Calculator

What this calculator does

The Calorie & TDEE Calculator estimates your Total Daily Energy Expenditure — the total calories your body burns in a normal day — from five inputs: gender, age, height, weight, and activity level. It then converts that number into practical daily calorie targets for losing weight slowly, losing weight at a steady clip, maintaining, or gaining weight.

TDEE is the number you actually care about when you sit down to plan a diet. Your body weight moves based on how the calories you eat compare to the calories you burn. Eat less than your TDEE and you lose weight over time. Eat more and you gain. The calculator gives you the maintenance line and the three most common offsets from it, so you can pick a starting calorie goal without doing the arithmetic yourself.

Who actually needs this

A few real situations where this is the right tool:

• You want to start a cut and need a sensible calorie target — not a guess pulled off a magazine cover.
• You're trying to gain muscle and want to know what a small surplus actually looks like in kcal/day.
• You've been eating the same way for years and your weight has drifted; you want to see what maintenance probably is now.
• You're returning to training after a long break and your old calorie targets no longer match your activity.
• You're tracking macros in an app and need a daily calorie budget to work back from.

If you're an athlete on a structured plan with a coach, or you have a medical condition that affects metabolism (thyroid disease, chronic medication that changes appetite or body composition, recovery from an eating disorder), a generic equation is a starting point at best. Talk to a professional who can look at your numbers.

How to use it

Pick a gender (the BMR formula uses a different constant for men and women), then fill in height in centimeters, age in years, and weight in kilograms. The inputs are metric only — there is no unit toggle. If you work in pounds and feet, convert before typing:

• Pounds to kilograms: multiply by 0.4536. So 165 lb is about 74.8 kg.
• Feet/inches to centimeters: turn it all into inches, then multiply by 2.54. So 5'10" is 70 in × 2.54 = 177.8 cm.

Then pick the activity level that honestly matches your average week, not your best one:

• Sedentary (office job) — desk work, little walking, no structured exercise.
• Light (1–3 days/week) — light exercise or sport a couple of days a week, mostly seated otherwise.
• Moderate (3–5 days/week) — regular gym, running, or sport most weekdays. This is the default.
• Active (6–7 days/week) — daily training, or a physically demanding job plus exercise.
• Very Active (athlete) — twice-a-day training, hard manual labor, or competitive sport.

There is no submit button. The result card appears the moment age, weight, and height all hold valid numbers and updates live as you change anything. The age field accepts 1–120, weight 1–500 kg, and height 50–300 cm — wide enough that almost everyone fits without hitting the bounds.

How it works under the hood

The calculator runs the Mifflin-St Jeor equation for Basal Metabolic Rate. BMR is the calories you'd burn if you spent the entire day lying still — just the energy cost of running your organs, maintaining body temperature, and keeping cells working.

The two formulas are:

• Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
• Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

The only structural difference is the trailing constant: +5 for men, −161 for women. That 166-kcal gap captures the average difference in lean body mass between men and women at the same height and weight.

TDEE is then BMR multiplied by an activity factor:

• Sedentary: ×1.2
• Light: ×1.375
• Moderate: ×1.55
• Active: ×1.725
• Very Active: ×1.9

That multiplier covers everything BMR doesn't: walking, fidgeting, the thermic effect of digesting food, structured exercise, and recovery from it. The gap between Sedentary and Very Active is huge — close to a 60% swing on the same person — which is why honest activity self-reporting is the single biggest lever in the whole calculation.

The three weight-change targets are fixed daily calorie offsets from TDEE:

• Mild Weight Loss (−0.25 kg/week): TDEE − 250 kcal/day
• Weight Loss (−0.5 kg/week): TDEE − 500 kcal/day
• Weight Gain (+0.5 kg/week): TDEE + 500 kcal/day

Those offsets come from the rule of thumb that a kilogram of body fat stores roughly 7,700 kcal, so a 500 kcal/day deficit predicts about half a kilogram of fat loss per week. Reality is messier than that — water shifts, glycogen changes, and adaptive thermogenesis all blur the picture — but it's a reasonable starting estimate over a multi-week stretch.

A worked example

Let's run it for a 30-year-old man, 80 kg, 180 cm, training moderately four times a week.

BMR: 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day.

TDEE: 1,780 × 1.55 ≈ 2,759 kcal/day. That's the maintenance line.

From there the targets fall out:

• Mild loss: 2,759 − 250 = 2,509 kcal/day for roughly 0.25 kg lost per week.
• Steady loss: 2,759 − 500 = 2,259 kcal/day for roughly 0.5 kg lost per week.
• Gain: 2,759 + 500 = 3,259 kcal/day for roughly 0.5 kg gained per week.

Same person, same height, different gender — a 30-year-old woman at 80 kg and 180 cm — has BMR = 800 + 1,125 − 150 − 161 = 1,614 kcal/day, and TDEE around 2,502 kcal/day at the same activity factor. That 166 kcal/day gap propagates through every downstream number.

What the result is and isn't

It's an estimate, not a measurement. Mifflin-St Jeor was published in 1990 and validated against indirect calorimetry, and it's usually within about 10% of measured BMR for healthy adults. Ten percent of a 1,800 kcal BMR is 180 kcal — about a large banana — which sounds small but accumulates. Two people who look identical on paper can have BMRs that differ by a couple of hundred calories because of body composition, gut microbiome, NEAT (the calories you burn fidgeting and pacing), and dozens of smaller factors the equation can't see.

The TDEE number inherits that uncertainty and adds more, because the activity multiplier is broad. A 1.55 factor lumps everyone from "I walk my dog and go to the gym Tuesday and Thursday" together with "I run 40 km a week." There's no way a five-bucket dropdown captures real activity precisely.

What this means in practice: use the number as a starting point for two to three weeks, weigh yourself consistently (same time of day, same conditions), and see what your weight trend does. Then adjust.

Common pitfalls

• Overestimating activity. Most people overshoot. "Active" sounds modest but is six to seven days of real training. If you're sedentary at a desk for nine hours and then go to the gym four times a week, you're probably Moderate, not Active.
• Forgetting to recalculate. If you lose 10 kg, your BMR drops because there's less of you to keep alive. Re-run the calculation every 4–6 kg of body weight change.
• Treating the loss targets as ceilings. The −500 kcal/day target is a deficit, but you still have to actually eat that many calories. Eating well below the loss target isn't faster progress — it's a recipe for losing muscle alongside fat and rebounding when the diet ends.
• Forgetting drinks and condiments. Olive oil, dressings, milk in coffee, juice, and beer add up quickly. A "small" pour of olive oil is 240 kcal. The TDEE number is honest; food tracking has to be honest too.
• Ignoring scale noise. Day-to-day weight swings of 1–2 kg from water, sodium, and gut contents are normal. Trend over 2–3 weeks beats any single weigh-in.
• Cutting and bulking at the same time. If your weight isn't moving in either direction over a month at a chosen target, you're at maintenance — that's information, not failure.

What to do if the number looks wrong

Two failure modes are common:

"This is way more than I eat." Either your tracking is leakier than you think (very common — restaurant portions, oils, and snacks are routinely undercounted by 20–40%), or your activity multiplier is too high, or both. Drop the multiplier one notch, log every bite and sip for a week, and reweigh.

"There's no way I'd lose weight on that." Possible reasons: your activity multiplier is too low, you're underweighing your portions, or there's a real metabolic adaptation from a long previous diet. Eat at the calculated TDEE for 2–3 weeks at a consistent multiplier and watch the scale. If you're maintaining, the number is approximately right. If you're gaining, the true TDEE is lower than estimated and you should adjust intake down by 100–200 kcal and reassess.

Either way: the calculator gives you a hypothesis. Your scale and a food log tell you whether the hypothesis is right.

When not to use it

• Pregnancy or breastfeeding. Both raise energy needs substantially, and Mifflin-St Jeor wasn't built for them. Ask your OB or a registered dietitian.
• Children and teenagers. Growth changes the equation. The activity factors assume an adult body.
• Recovery from an eating disorder. Algorithmic calorie targets can be actively harmful here. Work with a clinical team.
• Thyroid disease, medication changes, or other conditions that alter metabolism. The equation can't see your endocrine profile.
• Very high body fat or very low body fat. Mifflin-St Jeor assumes typical body composition; at extremes (BMI under ~18.5 or over ~40) accuracy drops, since BMR tracks lean mass more than total mass.
• Elite athletes or people with very large muscle mass. Equations based on total body weight tend to overestimate BMR for very heavy, very lean people. The Katch-McArdle formula (which uses lean body mass directly) is a better fit if you know your body fat percentage.

Related calculators and concepts

TDEE is the calorie budget. Most people want to know what to do with it next:

• Macro Calculator — splits your daily calories into protein, carbs, and fats. Protein is the macro most worth setting first; carbs and fats fill in around it.
• BMI Calculator — quick screen for whether your weight is in a healthy range for your height. Blunt instrument but a useful sanity check.
• Ideal Weight Calculator — estimates a target weight using classical formulas. Useful for setting a long-term direction.
• Body Fat Calculator — if you can estimate body fat percentage, lean body mass becomes available and Katch-McArdle gets you a slightly more personal BMR.

A couple of related concepts worth naming explicitly:

• NEAT (Non-Exercise Activity Thermogenesis) — the calories you burn fidgeting, pacing, standing, gesturing. NEAT varies wildly between people and is mostly what makes one office worker's TDEE 300 kcal higher than another's. The activity factor tries to absorb it, imperfectly.
• TEF (Thermic Effect of Food) — about 10% of what you eat goes to digesting it, and protein has a higher TEF than carbs or fat. This is already baked into the activity multipliers.
• Metabolic adaptation — your body fights long calorie deficits by lowering BMR slightly. After a long cut, your real TDEE is usually a bit lower than the formula predicts. Diet breaks and slow refeeds help.

Sensible defaults to start with

If you're new to all this, start here:

• Pick the activity level one notch below what feels right. Most people overshoot.
• For weight loss, start at the Mild (−250 kcal/day) target. It's slower but easier to stick with, preserves more muscle, and leaves room to drop further if progress stalls.
• For weight gain, the +500 kcal/day target is fine for a true bulk; if you're recomping and care about leanness, a smaller surplus of 200–300 kcal/day above TDEE is gentler.
• Weigh yourself daily, average the week, and look at the trend month over month — not day over day.
• Re-run the calculator every 4–6 kg of weight change, or every couple of months if your training volume changes meaningfully.

The number on screen is a hypothesis. Your scale and a food log over a few weeks tell you whether the hypothesis fits you. Treat it as a starting point and iterate from there.