Calorie Calculator

It's a two-step process. First, it calculates your BMR (Basal Metabolic Rate) using the Mifflin-St Jeor equation, based on your age, sex, height, and weight — this is the energy your body burns at complete rest. Second, it multiplies your BMR by an activity factor (ranging from 1.2 for sedentary up to 1.9 for extra active) to estimate your TDEE (Total Daily Energy Expenditure) — your true maintenance calories including movement and exercise. From there, it adjusts up or down based on your stated goal (typically ±250–500 kcal/day) to give you a target calorie intake.

Activity level is the single biggest multiplier in this calculation, and picking the wrong one is the most common reason people end up with an inaccurate calorie target. Sedentary means little to no structured exercise (desk job, minimal walking). Lightly active means light exercise 1–3 days/week. Moderately active means moderate exercise 3–5 days/week. Very active means hard exercise 6–7 days/week. Extra active is reserved for very hard daily training combined with a physically demanding job. Most people overestimate their activity level — if in doubt, choose the lower of two options and adjust based on real-world results over 2–3 weeks.

A few common explanations: activity level may be set too high relative to your actual movement, leading to an overestimated calorie target; food tracking accuracy issues (unlogged bites, inaccurate portion estimates, and untracked cooking oils/sauces commonly add 100–300 unaccounted calories per day); water retention masking genuine fat loss trends over short periods (weigh weekly averages, not single days); or your TDEE has genuinely decreased somewhat as you've lost weight (a smaller body burns fewer calories, so your deficit shrinks over time even at a constant intake — recalculate periodically as you lose weight).

500 kcal/day is a very commonly used deficit because it corresponds to roughly 0.5kg (1lb) of fat loss per week (since approximately 7,700 kcal equals 1kg of body fat), which is considered a sustainable, evidence-supported rate for most people. A gentler 250 kcal/day deficit gives a slower, sometimes more sustainable rate of about 0.25kg/week — a reasonable choice for people wanting a lower-stress approach or with a smaller amount to lose. Larger deficits (750–1000+ kcal/day) can work short-term but increase risk of muscle loss, metabolic adaptation, and rebound hunger, and are generally not recommended for extended periods.

Both approaches (consistent daily calories versus cycling higher on training days and lower on rest days) can work equally well for weight management, since what ultimately matters most is your total weekly calorie balance rather than daily precision. Consistent daily intake is simpler to plan and track. Calorie cycling (eating more on harder training days) can help performance and recovery around workouts and may feel more intuitive to some people. Neither is objectively superior for fat loss or muscle gain outcomes — choose whichever approach you can sustain most consistently over time.

Recalculate whenever your weight changes meaningfully (roughly every 5–7kg lost or gained), since your BMR and TDEE both shift as your bodyweight changes — a lighter body burns somewhat fewer calories at rest and during activity. Also recalculate if your activity level changes significantly (starting or stopping a training programme, changing job type). For most people actively working toward a goal, checking in and recalculating every 4–6 weeks alongside a broader progress review (weight trend, measurements, photos) is a reasonable cadence.

This calculator provides a starting calorie target for weight gain (+500 kcal/day by default) but cannot itself determine what proportion of gained weight will be muscle versus fat — that depends heavily on your training programme, protein intake, and how large a surplus you use. A smaller, more controlled surplus (roughly 200–300 kcal/day above maintenance) combined with consistent progressive resistance training and adequate protein (1.6–2.2g/kg) tends to produce a higher proportion of lean muscle gain relative to fat gain, compared to a larger, more aggressive surplus.

Mifflin-St Jeor (1990) is generally considered the most accurate widely available BMR formula for the general population, validated against indirect calorimetry across a broad range of body types. Using a more accurate BMR formula as the foundation of this calculation means your resulting calorie target starts from a more reliable baseline than older formulas like the original 1919 Harris-Benedict equation, which tends to run 5–15% higher, particularly for those with more body fat. Since every subsequent number (TDEE, deficit, surplus) is built on this base BMR figure, starting with a more accurate formula improves the reliability of your final calorie target.

Yes — many people successfully lose weight through less precise approaches like intuitive eating adjustments, portion control, or simply reducing intake of ultra-processed and calorie-dense foods, without formally tracking every calorie. However, having an approximate calorie target (like the one this calculator provides) gives you a concrete reference point to sanity-check your intake against, particularly useful if progress stalls and you want to identify whether the issue is portion sizes, meal frequency, or specific high-calorie foods creeping into your diet without you fully realising it.

General guidelines suggest not going below approximately 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision, as intakes below these levels risk inadequate micronutrient intake, excessive muscle loss, hormonal disruption, and unsustainable hunger. These are rough population guidelines rather than precise individual thresholds — very small or short individuals may have genuinely lower BMRs, while larger or more active individuals should generally eat considerably more than these floor values. If your calculated target from this calculator falls near or below these minimums, consider a more modest deficit or consult a registered dietitian rather than pushing calories lower.

Small discrepancies (100–200 kcal) between different calculators and apps are normal and expected — they often use slightly different BMR formulas (Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle), different activity factor definitions, or round numbers differently. Larger discrepancies usually stem from different activity level selections between the tools, or one tool factoring in additional variables (like tracked exercise calories from a wearable device) that another doesn't. Treat any calculator's output as a reasonable starting estimate to be refined by 2–3 weeks of real-world tracking against your actual weight trend, rather than an exact, unquestionable number.

Not necessarily, and very low intakes can backfire. Severe, sustained calorie restriction triggers metabolic adaptation — your body reduces its energy expenditure beyond what weight loss alone would predict, partly through hormonal changes and partly through reduced spontaneous movement — meaning the "faster" deficit shrinks over time even at a constant low intake. Very low intakes also increase muscle loss risk, hunger and cravings, and the likelihood of abandoning the diet altogether. A moderate, sustainable deficit maintained consistently over months typically produces better long-term fat-loss outcomes than an aggressive short-term crash approach.

Start eating consistently at your calculated target for 2–3 weeks while tracking your weight (ideally daily, then averaged weekly to smooth out normal fluctuations). If your weight trend matches your goal (losing at your intended rate, maintaining, or gaining at your intended rate), your target is working well. If not, adjust calories up or down by 100–200 kcal and reassess after another 2–3 weeks. Pair your calorie target with our Protein Calculator to set an adequate protein intake, and our Macro Calculator to fill in the rest of your nutrition plan.