BMR
Estimated energy used at rest for essential body functions. It excludes daily movement and exercise.
Understanding the results
Four numbers, four different questions
TDEE
BMR after the selected activity factor. It is the starting estimate for maintaining current weight.
BMI
A screening ratio of weight to height. It cannot distinguish muscle from fat, so read it alongside other information.
WHR
Waist-to-hip ratio, a screening measure of fat distribution. Measurement technique affects the result.
Transparent methodology
How the calorie estimate works
Resting energy expenditure is estimated with the Katch–McArdle equation from your weight and body-fat percentage, which is why body fat is a required input. Fat-free mass is weight × (1 − body fat %), and BMR = 370 + 21.6 × fat-free mass.
BMR is multiplied by the selected activity factor to estimate total daily energy expenditure (TDEE). The goal then applies a moderate adjustment: −15% for fat loss, 0% for maintenance and +10% for muscle gain.
BMI uses weight divided by squared height. WHR uses waist divided by hip circumference and compares the result with WHO adult screening thresholds of 0.85 for females and 0.90 for males. Both are screening measures, not diagnoses.
The highlighted target is the mathematical centre of the estimate. Because the underlying BMR and TDEE are themselves approximations from prediction equations and broad activity categories, treat the ±10% band as a practical working range rather than a precise figure, and adjust it against a stable 2–4 week trend.
The goal-based macro split is a practical starting distribution, not a clinical prescription. Grams are derived with 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat; fibre is shown as an adult minimum of 25 g/day.
Katch–McArdle
BMR = 370 + 21.6 × fat-free mass (kg)Fat-free mass = weight × (1 − body fat %).TDEE a cíl
TDEE = BMR × activity; target = TDEE × goal adjustmentFat loss −15%, maintenance 0%, muscle gain +10%.BMI a WHR
BMI = kg ÷ m²; WHR = waist ÷ hipsThese are screening measures, not diagnoses.FAQ
Good to know
Is TDEE an exact number?
No. It is a starting estimate. Sleep, spontaneous movement, training, health and measurement error all affect real expenditure. The range is more useful than treating one calorie value as exact.
Why do you ask for sex?
Biological sex selects the waist-to-hip ratio screening thresholds and the matching body-composition illustration. It is not a statement about gender identity.
Which BMR equation does the calculator use?
Katch–McArdle, based on fat-free (lean) mass. It uses your weight and body-fat percentage rather than age and height, which is why body fat is a required input. Because a body-fat estimate is only as good as its measurement, treat the result as an approximation.
How should I measure waist and hips?
Measure the waist horizontally halfway between the lowest rib and the top of the hip bone, and hips at the widest point, with the tape snug but not compressing skin. Use the same technique when comparing changes.
How do I translate calories into food?
Treat the target as a daily average. Build meals around vegetables or fruit, a protein source, a suitable carbohydrate source and fats, then compare your recorded 2–4 week average with the calculated range.
What is a calorie deficit?
A deficit means average energy intake is below average expenditure. This tool uses a moderate 15% starting deficit; faster is not automatically better or more sustainable.
What is the difference between kcal and kJ?
They are two units of energy. One kilocalorie equals exactly 4.184 kilojoules, so both figures describe the same calculated target.
Should I eat below my BMR?
BMR is not a personal safety threshold by itself, but aggressive restriction can be harmful. If the target feels unsustainable, you are pregnant, under 18, have a medical condition or an eating-disorder history, use professional guidance.