Tracking macros without a calorie target is guesswork with more arithmetic. The target comes first, and it comes from your total daily energy expenditure, which is your resting metabolism plus everything you do on top of it. The calculator below works out both, then divides the result into protein, fat, and carbohydrate.
Our step-by-step guide to tracking macros covers the logging habit and how to hold to it.
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TDEE and macro calculator
Enter your details and goal. The tool returns your resting metabolic rate, your total daily energy expenditure, a calorie target, and the protein, fat, and carbohydrate grams that fit it.
Resting metabolic rate
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TDEE (maintenance)
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Your calorie target
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Protein
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Fat
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Carbohydrate
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Predictive equations estimate energy expenditure to within roughly 10 percent for most people and can be further out at the extremes of body size.1 Treat the figure as a starting point and adjust it against what the scale actually does over two to three weeks.
How the calculation works
Three steps sit behind the numbers above.
1. Resting metabolic rate
The tool uses the Mifflin-St Jeor equation, which estimates the calories your body burns at rest from weight, height, age, and sex. It was validated against measured resting energy expenditure and predicted it more accurately than the older Harris-Benedict equation in a systematic review of the available formulas.1 For men the equation is 10 × weight in kg, plus 6.25 × height in cm, minus 5 × age, plus 5.
2. Total daily energy expenditure
Resting rate is multiplied by an activity factor between 1.2 and 1.9. This is the weakest link in every TDEE calculator, because the factor compresses training, walking, fidgeting, and job movement into one number. Non-exercise activity varies by hundreds of calories a day between people of similar size, which is a large share of the error in any predicted figure.2
3. The calorie target and the split
A deficit or surplus is applied as a percentage of TDEE rather than a flat number, so it scales with body size. Protein is set first, at 1.8 g/kg for maintenance and gaining or 2.2 g/kg in a deficit, where protein needs are higher to protect lean mass.3 Fat is set at 0.8 g/kg, comfortably above the level at which hormone production is affected. Carbohydrate takes whatever is left.
Practical takeaway: use the number for two to three weeks and weigh yourself under the same conditions. Adjust by 100 to 200 calories based on the trend, not on any single morning.
Why fat is set before carbohydrate
Carbohydrate is treated as the flexible macro here for a specific reason. There is no dietary requirement for carbohydrate in the sense there is for protein and fat, but there is a floor below which dietary fat starts to interfere with hormone production. Very low fat intake, in the region of 20 percent of calories or less, has been associated with lower total testosterone in men. Effect sizes across studies are small and the evidence is mixed.4 Setting fat at 0.8 g/kg keeps you clear of that floor without spending the whole calorie budget on it.
Below roughly 50 g of carbohydrate a day the tool will tell you it has cut fat to make room. That is a signal, and the useful response is usually a smaller deficit rather than a more aggressive split.
Picking the right activity multiplier
The activity factor is the weakest input in the calculation and the one people most often overstate. Four training sessions a week is a small share of a 168-hour week, and what you do in the other 164 hours moves the total more than the sessions do. Use the descriptions below rather than the label that sounds most like how you think of yourself.
| Multiplier | What it assumes about a normal day | Rough daily steps |
|---|---|---|
| 1.2 | Desk work, car commute, no structured training, no manual tasks at home | Under 5,000 |
| 1.375 | Desk work plus 1 to 3 training sessions, some walking built into the day | 5,000 to 7,500 |
| 1.55 | Desk work plus 3 to 5 sessions, or a job with regular movement | 7,500 to 10,000 |
| 1.725 | 6 to 7 sessions a week, or a moderately physical job plus training | 10,000 to 15,000 |
| 1.9 | A genuinely physical job on top of daily training | Over 15,000 |
Two rules make this easier. If you are between two levels, take the lower one, since overestimating activity is the more common error and it produces a target that quietly removes your deficit. And if you wear a tracker, use its step count rather than your impression of the week.
Choosing a deficit size
| Approach | Deficit | Typical rate | Who it suits |
|---|---|---|---|
| Slow cut | 10% below TDEE | ~0.25 to 0.5 lb a week | Already lean, wants to keep training quality and strength |
| Standard cut | 20% below TDEE | ~0.5 to 1 lb a week | Most people with 15 lb or more to lose |
| Maintenance | At TDEE | Stable | Recomposition, or holding a result after a cut |
| Lean gain | 10% above TDEE | ~0.25 to 0.5 lb a week | Building muscle without adding much fat |
Larger deficits produce faster weight loss and a larger share of that loss from lean tissue, particularly when protein is not held high and resistance training is not part of the plan.3 A slower rate with adequate protein and lifting preserves more of what you want to keep.
What the number cannot account for
Predicted TDEE is an estimate, and three things move real expenditure away from it.
- Adaptive thermogenesis. Energy expenditure falls during sustained weight loss by more than the change in body mass alone predicts, so the target that worked at the start of a cut overshoots by the end of it.5
- Non-exercise activity. People unconsciously move less in a deficit, and the size of that reduction differs a great deal between individuals.2
- Body composition. Equations based on total weight do not know how much of it is lean tissue. A very muscular man is usually underestimated, and a man carrying a lot of fat mass is usually overestimated. If you know your body-fat percentage, the FFMI calculator gives you the lean-mass figure that explains the gap.
When the arithmetic is right and the weight will not move
A stall at a correctly calculated deficit, held for a month with accurate logging, is worth investigating rather than answering with a further calorie cut. Untreated hypothyroidism lowers resting expenditure and causes weight gain.6 Low testosterone shifts body composition toward fat mass and away from lean mass at any given calorie intake.7 Poor sleep raises appetite-driving hormones and lowers satiety signalling.8 None of those is fixed by a smaller number in a tracking app.
Frequently asked questions
Total daily energy expenditure: the calories you burn in a day from your resting metabolism, the food you digest, your training, and everything else you do. It is the number a calorie target is set against.
Roughly 10 to 20 percent below your TDEE, which the tool calculates for you. For most men that lands between 400 and 600 calories below maintenance and produces about half a pound to a pound a week.
Mifflin-St Jeor predicted measured resting energy expenditure more accurately than the alternatives in a systematic review, and it is the equation used here.1 It still carries roughly 10 percent error in either direction for any individual.
Calories determine the direction of weight change. Macros determine a good deal of what the change is made of. In a deficit, higher protein plus resistance training shifts the loss toward fat and away from lean mass.3
Every 10 to 15 lb of weight change, or whenever your training volume changes meaningfully. TDEE falls as you lose weight, so an old target eventually stops producing a deficit.5
The bottom line
Take the target, hold it for three weeks, and let the scale trend correct the estimate. Protein first, fat above the floor, carbohydrate in the remaining space. If the trend does not follow accurate logging over a full month, the problem is upstream of the arithmetic.
When the plan is right and the results are not
A deficit held accurately for a month that produces no weight change is a finding, not a failure of willpower. Thyroid function, testosterone, and sleep all move the number this calculator can only estimate. Opt Health measures them and puts a physician on the result. Become a member.
References
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789.
- Levine JA. Non-exercise activity thermogenesis (NEAT). Best Pract Res Clin Endocrinol Metab. 2002;16(4):679-702.
- Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138.
- Whittaker J, Wu K. Low-fat diets and testosterone in men: systematic review and meta-analysis of intervention studies. J Steroid Biochem Mol Biol. 2021;210:105878.
- Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010;34(suppl 1):S47-S55.
- Jonklaas J, Bianco AC, Bauer AJ, et al. Guidelines for the treatment of hypothyroidism. Thyroid. 2014;24(12):1670-1751.
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744.
- Spiegel K, Tasali E, Penev P, Van Cauter E. Brief communication: sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004;141(11):846-850.
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