Calorie Calculator

About Calorie Calculator

Your Total Daily Energy Expenditure (TDEE) — the total number of calories your body burns in a day — is the single most important number in any nutrition plan. If you eat below your TDEE, you lose weight. Above it, you gain. At it, you maintain. The challenge is that TDEE is genuinely difficult to determine without laboratory measurements, so we rely on validated equations that use age, sex, height, weight, and activity level as inputs. This free calorie and TDEE calculator supports both metric (kg/cm) and imperial (lbs/ft/in) inputs and uses the Mifflin-St Jeor equation by default — the most extensively validated formula for estimating Basal Metabolic Rate (BMR, the calories your body burns at complete rest) in general populations. That BMR is multiplied by your chosen activity multiplier (sedentary through extra active) to produce your TDEE. For users who know their body fat percentage, enabling the advanced mode switches to the Katch-McArdle formula, which derives BMR from lean mass alone, making it significantly more accurate for highly muscular individuals or those with very low body fat. Beyond the single TDEE number, the calculator outputs four practical calorie targets: aggressive fat loss (TDEE minus 1,000 kcal), moderate fat loss (TDEE minus 500 kcal), maintenance, and lean bulk (TDEE plus 500 kcal), along with a personalised macronutrient breakdown in grams and percentages. Everything runs in your browser with no account required.

How to Use Calorie Calculator

1. Enter Your Stats: Input your age, gender, height, and weight in your preferred unit system.
2. Select Your Activity Level: Choose the activity level that best describes your typical week — sedentary, lightly active, moderately active, very active, or extra active. This has the largest effect on your TDEE.
3. Read Your TDEE and Targets: See your maintenance TDEE, the four calorie targets, and your macro breakdown. Use maintenance for tracking, the deficit targets for fat loss, or the surplus for muscle building.

Key Features

• TDEE Calculation with Activity Multiplier: Calculates your Total Daily Energy Expenditure by multiplying your Basal Metabolic Rate by your activity level: from sedentary (desk job, no exercise) to extra active (intense physical job plus exercise). The activity multiplier is the biggest source of variation between people with similar weights.
• Mifflin-St Jeor and Katch-McArdle Formulas: Uses the Mifflin-St Jeor equation (the most validated formula for general populations) by default. Enable the advanced mode and enter your body fat percentage to switch to Katch-McArdle, which derives BMR from lean mass alone — more accurate for muscular individuals.
• Four Practical Calorie Targets: Shows ready-to-use calorie targets: aggressive fat loss (−1,000 kcal), moderate fat loss (−500 kcal), maintenance (TDEE), and lean bulk (+500 kcal). No manual arithmetic required.
• Personalised Macro Breakdown: Generates a protein, carbohydrate, and fat breakdown in grams and percentages, scaled to your activity level. Protein targets range from 0.8 g/kg (sedentary) to 1.6 g/kg (extra active) based on evidence-based muscle preservation research.
• Metric and Imperial Support: Enter height and weight in kg/cm or lbs/ft/in. Switch between systems without re-entering values.
• 100% Browser-Based: All calculations are local. No personal health data (age, weight, height, body fat) is transmitted to any server.

Benefits

• Set a Data-Driven Calorie Target: Rather than following a generic 2,000 kcal/day recommendation that assumes an average person with an average lifestyle, calculate your personal TDEE and set a target based on your actual body size and activity level.
• Understand the Rate of Expected Weight Change: A 500 kcal/day deficit typically produces about 0.5 kg (1 lb) of fat loss per week. The calculator quantifies this: if your TDEE is 2,400 kcal and you eat 1,900 kcal, you know to expect roughly 0.5 kg/week loss.
• Calibrate Macros for Your Training: Protein targets are scaled by activity level. At sedentary, 0.8 g/kg preserves muscle. At very active, 1.6 g/kg supports muscle synthesis. The macro breakdown adjusts automatically based on your input.
• More Accurate Results for Athletes: The Katch-McArdle mode (enabled by entering body fat %) calculates BMR from lean mass rather than total weight, which is substantially more accurate for muscular individuals where Mifflin-St Jeor tends to underestimate.

Supported Formats & Capabilities

• Metric input: kg, cm, age
• Imperial input: lbs, feet, inches, age
• Optional: body fat percentage for Katch-McArdle mode

Common Problems & Solutions

I'm eating below my TDEE but not losing weight. Why?

Calculators provide an estimate with ±10–15% individual variance. Track your actual food intake precisely with a calorie tracking app for 2–3 weeks and compare to your scale weight trend. If weight is stable, your actual TDEE is roughly equal to your intake regardless of what the calculator says.

What activity level should I choose?

Most people overestimate their activity level. Sedentary = desk job, no gym. Lightly active = desk job plus 1–2 exercise sessions/week. Moderately active = active job or 3–4 gym sessions/week. Very active = physical job or 5–6 intense sessions/week. Extra active = physically demanding job plus daily intense training.

Should I eat below 1,200 kcal to lose weight faster?

No. Eating below 1,200 kcal/day (women) or 1,500 kcal/day (men) risks nutrient deficiencies, muscle loss, metabolic adaptation, and is unsustainable. Very low calorie diets (VLCDs) should only be done under medical supervision.

The Katch-McArdle result is very different from Mifflin-St Jeor. Which is correct?

If your body fat percentage is accurate, Katch-McArdle is likely more precise for you. Mifflin-St Jeor was validated on general populations including average body compositions — it tends to be less accurate at the extremes (very lean or very high body fat).

Pro Tips & Best Practices

• The activity multiplier is the biggest variable in your TDEE. When in doubt, choose one level lower than you think — most people overestimate their daily activity and then wonder why they are not losing weight despite eating at their 'calculated' TDEE.
• Use the TDEE as a starting point, then track your actual weight for 2–3 weeks. If you are gaining at maintenance, reduce by 100–200 kcal. If losing faster than intended, increase by the same amount. Real-world calibration beats any formula.
• For muscle building, a 250–500 kcal surplus is recommended for most people — enough to support protein synthesis without excessive fat gain. Eating 1,000+ kcal above maintenance mostly adds fat, not muscle.
• Protein is the most important macro to hit accurately during any calorie deficit. Adequate protein (1.6–2.2 g/kg of bodyweight during cutting) minimises muscle loss while dieting.

Privacy & Data Security

All TDEE, BMR, and macro calculations run entirely in your browser using standard nutritional science formulas. Your age, weight, height, gender, and body fat percentage are processed locally in JavaScript memory and are never transmitted to any server. No personal health data is collected or stored.

Frequently Asked Questions

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep organs functioning. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to account for daily movement, exercise, and work. TDEE is the number to base your diet on.

When should I use Katch-McArdle instead of Mifflin-St Jeor?

Katch-McArdle calculates BMR from lean mass rather than total body weight, making it more accurate for people who carry significant muscle mass or have very low body fat. If you know your body fat %, enable the advanced mode.

How are the macros calculated?

Protein is scaled by activity level: 0.8–1.6 g/kg bodyweight. Fat is set at 25% of total calories for hormonal health. Remaining calories go to carbohydrates. These are evidence-based starting targets — individual needs vary by training type and goals.

How many calories should I eat to lose weight?

A 500 kcal/day deficit below TDEE typically produces around 0.5 kg (1 lb) of fat loss per week. A 1,000 kcal deficit can produce ~1 kg/week but risks muscle loss without sufficient protein. Never go below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.

How accurate is this calorie calculator?

Mifflin-St Jeor has a mean error of ±10% in healthy adults. Individual metabolic rates vary due to genetics, hormones, and adaptation. Treat the result as a calibrated starting point and adjust by 100–200 kcal based on 2–3 weeks of real-world tracking.

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