Example data table
| Weight |
Body fat |
Lean mass |
BMR estimate |
Activity factor |
TDEE estimate |
| 70 kg |
15% |
59.5 kg |
1,655 calories |
1.55 |
2,565 calories |
| 85 kg |
22% |
66.3 kg |
1,802 calories |
1.375 |
2,478 calories |
| 95 kg |
28% |
68.4 kg |
1,847 calories |
1.725 |
3,185 calories |
Katch McArdle calorie planning guide
Why this method helps
A Katch McArdle calorie calculator is useful when body fat is known. It starts with lean body mass instead of total body weight. This makes the estimate more personal for lifters, athletes, and people changing body composition. Two people can weigh the same amount. One may carry more muscle. The other may carry more fat. Their resting needs can differ. This method tries to reflect that difference.
How the estimate works
The calculator first estimates lean body mass. It removes the entered fat percentage from body weight. It then applies the Katch McArdle resting energy formula. The result is basal metabolic rate. That value is the energy needed at rest. It does not include training, walking, work, or daily movement. For daily calories, the calculator multiplies BMR by an activity factor. A desk job uses a lower factor. Heavy training uses a higher factor.
Goal and macro planning
Goal calories are then built from TDEE. A fat loss goal subtracts energy. A gaining goal adds energy. A maintenance goal keeps calories close to daily output. This page also estimates protein, fat, and carbohydrate targets. Protein is based on lean mass. Fat can be set as a percentage of calories. Carbohydrates receive the remaining energy. This makes macro planning easier.
Using results wisely
Use the result as a planning guide, not a medical rule. Body fat measurements can contain error. Activity factors are also estimates. Track body weight, training, hunger, and energy for two to four weeks. Then adjust calories by a small amount. A steady trend matters more than a single day. The projection panel shows possible weekly change from the chosen deficit or surplus. It uses a simple energy balance assumption. Real changes can differ because water, glycogen, digestion, and adaptation shift over time.
Better tracking habits
This calculator works best with honest inputs. Enter a realistic body fat percentage. Choose the activity level that matches your normal week. Use goal adjustment slowly. Large cuts can reduce performance. Large surpluses can add excess fat. Small changes are easier to follow. Clear records help you refine decisions. Recalculate after major weight changes. Lean mass and fat mass may shift. New numbers can improve targets. Pair the estimate with sleep, steps, resistance training, and balanced meals. Consistency makes the calculation more useful over time too.
Formula used
The Katch McArdle equation estimates resting energy from lean body mass. It is useful when body fat percentage is available.
Lean Body Mass: LBM = body weight in kg × (1 − body fat percent ÷ 100)
BMR: BMR = 370 + (21.6 × LBM in kg)
TDEE: TDEE = BMR × activity factor
Loss target: Target calories = TDEE × (1 − adjustment percent ÷ 100)
Gain target: Target calories = TDEE × (1 + adjustment percent ÷ 100)
Protein: Protein grams = lean body mass × protein rate
Fat: Fat grams = target calories × fat percent ÷ 100 ÷ 9
Carbs: Carb grams = remaining calories ÷ 4
How to use this calculator
- Select the unit system you want to use.
- Enter your body weight and optional height.
- Enter your estimated body fat percentage.
- Choose the method used for your body fat estimate.
- Select the activity level that matches your normal week.
- Pick maintenance, fat loss, or lean gain.
- Adjust protein, fat, projection days, and rounding.
- Press Calculate and review the results above the form.
- Use the CSV or PDF button to save your result.
FAQs
What is the Katch McArdle calorie formula?
It estimates basal metabolic rate from lean body mass. The formula is BMR = 370 + 21.6 × lean body mass in kilograms.
Who should use this calculator?
It suits people who know their body fat percentage. Athletes, lifters, and body recomposition users may find it more useful than weight-only equations.
Is body fat percentage required?
Yes. This method depends on lean body mass. You need a reasonable body fat estimate for the calculation to work.
What is BMR?
BMR means basal metabolic rate. It estimates calories your body uses at rest before activity and exercise are added.
What is TDEE?
TDEE means total daily energy expenditure. It multiplies BMR by an activity factor to estimate daily maintenance calories.
Are macro targets exact?
No. They are planning estimates. Adjust them based on progress, training, hunger, digestion, and your nutrition preferences.
Why can projected weight change differ?
Water, glycogen, sodium, digestion, and metabolic adaptation can shift scale weight. Use trends over several weeks instead of one weigh-in.
Can I save my results?
Yes. After calculation, use the CSV button for spreadsheet records or the PDF button for a simple printable report.