The Macro Calculator in the Nutrition module works in five steps: resting expenditure (BMR), total daily expenditure (TDEE), the adjustment for the goal, the calorie target with a reference minimum and, last, protein, fat and carbs. This page shows each step with the constants the app uses. The terms are also in the glossary.
Where the calculation is done
- On the web, in the professional's dashboard: in a meal plan, select Edit on the goals card (Daily Goals or, in Calendar mode, “Goals for day” with the day's number) and then Open calculator. The window's title changes to Macro Calculator.
- Apply to goals copies the calories and macros of the result into the fields of the goal you are editing, which you can still change by hand. In weekly and calendar plans, that goal is the one for the scope chosen in Apply goal to, which opens on This day. To apply the result to every day, choose Whole plan before opening the calculator: changing the scope afterwards fills the fields again with that scope's goal. The values are only saved when you select Save. Back returns to the goals without applying.
- The fields come already filled in: in a plan with only one client, with the data from that client's profile; in other plans, with starting values (75 kg, 175 cm, 30 years and Male). Check them before applying. The calculator does not change the client's profile.
- A team member without permission to edit Nutrition opens the plan read-only, without the calculator.
- If you are a client, you do not do this calculation: you see the goals your professional set, as explained in View your meal plan for the day and your goals.
Step 1: resting expenditure (BMR)
BMR, or basal metabolic rate, is the energy the body uses at complete rest. The formula is chosen in Calculation formula and the calculator always opens on Mifflin-St Jeor. In the formulas, weight is in kg, height in cm and age in years.
| Formula | Men | Women |
|---|---|---|
| Mifflin-St Jeor | 10 × weight + 6.25 × height − 5 × age + 5 | 10 × weight + 6.25 × height − 5 × age − 161 |
| Harris-Benedict (revised) | 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age | 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age |
| Katch-McArdle | 370 + 21.6 × lean mass | 370 + 21.6 × lean mass |
In Katch-McArdle, lean mass is weight × (1 − body fat % ÷ 100). This formula asks for the Body fat (%) field, which always opens empty, and does not use height, age or sex; the sex you choose still counts for the reference minimum in step 4. Under Calculation formula, the screen describes the chosen formula and who it suits.
Step 2: total daily expenditure (TDEE)
TDEE, or total daily energy expenditure, is BMR multiplied by the factor of the Activity Level. The calculator opens on Moderate (3-5x/week).
| Activity Level | Description on screen | Multiplier |
|---|---|---|
| Sedentary (little exercise) | Desk job, little or no exercise. | 1.2 |
| Light (1-3x/week) | Training or light walks 1-3x a week. | 1.375 |
| Moderate (3-5x/week) | Moderate training 3-5x a week. | 1.55 |
| Active | Hard training 6-7x a week. | 1.725 |
| Very Active | Training twice a day or a physical job. | 1.9 |
Step 3: adjustment for the goal
The Goal adds calories to TDEE or takes them away. With Lose and Gain, Intensity appears; with Maintain, the adjustment is 0. The calculator opens on Maintain and, when the intensity appears, on Moderate.
| Goal | Intensity | Adjustment per day |
|---|---|---|
| Lose | Mild | −250 kcal |
| Lose | Moderate | −500 kcal |
| Lose | Aggressive | −750 kcal |
| Maintain | No intensity | 0 kcal |
| Gain | Mild | +150 kcal |
| Gain | Moderate | +300 kcal |
| Gain | Aggressive | +500 kcal |
With Aggressive, the result shows a warning: “Aggressive deficit: watch fatigue, mood and lean-mass retention. Reassess in 2 weeks.” when losing and “Aggressive surplus: risk of excess fat gain. Check body composition every 2 weeks.” when gaining.
Step 4: calorie target and reference minimum
The target is TDEE plus the adjustment. If it comes to less than 1500 kcal with the sex set to Male or less than 1200 kcal with Female, the calculator uses that minimum as the target and shows a warning saying it adjusted it. The minimum is fixed, the same for everyone of the same sex, and is not a clinical recommendation. The macros in step 5 start from this target.
Step 5: protein, fat and carbs
The macros split the target calories, at 4 kcal per gram of protein and of carbs and 9 kcal per gram of fat.
| Macro | How it is calculated |
|---|---|
| Protein | Weight × 2.2 g/kg when losing, × 1.6 g/kg when maintaining and × 2.0 g/kg when gaining. It uses total weight and is the same for both sexes. |
| Fat | The higher of two values: 0.8 g per kg of weight or 25% of the target calories ÷ 9. |
| Carbs | The target calories left after protein and fat, ÷ 4. Never less than 0. |
When the 0.8 g/kg minimum applies, the result shows “Fat raised to the minimum of 0.8 g/kg for hormonal health.”. If protein and fat already go past the target calories, carbs stay at 0 and the macros add up to more than the target.
The calculations use unrounded values. The screen shows the result rounded to whole numbers, so the macros can add up to a few kcal more or less than the target.
Accepted values
A field the formula uses that is empty or out of range shows “Between 30 and 300”, with that field's limits. While any field is like that, the result does not appear and Apply to goals is disabled.
| Field | Range | When it counts |
|---|---|---|
| Weight (kg) | 30 to 300 | In every formula |
| Height (cm) | 100 to 250 | Mifflin-St Jeor and Harris-Benedict (revised) |
| Age | 14 to 120, in whole years | Mifflin-St Jeor and Harris-Benedict (revised) |
| Body fat (%) | 3 to 70 | Katch-McArdle only |
An example
A 32-year-old man, 80 kg and 178 cm, with Mifflin-St Jeor, Moderate (3-5x/week), Lose and intensity Moderate:
| Value | Calculation | On screen |
|---|---|---|
| BMR | 10 × 80 + 6.25 × 178 − 5 × 32 + 5 = 1757.5 | 1758 |
| TDEE | 1757.5 × 1.55 = 2724.125 | 2724 |
| Adjustment | Lose, intensity Moderate | −500 |
| Target | 2724.125 − 500 = 2224.125, more than the 1500 minimum | 2224 |
| Protein | 80 × 2.2 = 176 | 176 g |
| Fat | 0.8 × 80 = 64 g against 2224.125 × 25% ÷ 9 = 61.8 g: the higher one applies | 64 g |
| Carbs | (2224.125 − 176 × 4 − 64 × 9) ÷ 4 = 236.03 | 236 g |
Because the fat minimum applies, the result also shows the note about the adjusted fat.
How far to trust the result
- The formulas estimate the average of groups of people. In a systematic review, Mifflin-St Jeor was the equation that came within 10% of measured resting expenditure in more people than the others, but with meaningful errors for individual people (Frankenfield et al., 2005).
- In a meta-analysis of 49 studies on strength training, protein beyond 1.62 g per kg per day brought no further gain in fat-free mass (Morton et al., 2018). The calculator uses 1.6 g/kg with Maintain and higher values with Lose and Gain.
- The note at the end of the result suggests tracking for 2 to 3 weeks and adjusting if needed.
Questions
Which formula should I choose?
According to the description on screen, Mifflin-St Jeor is the most accurate choice for most people, Harris-Benedict (revised) tends to give a slightly higher value and Katch-McArdle suits lean or athletic people better, because it uses body fat percentage.
Can I change the values after applying?
Yes. Apply to goals only fills in the fields: you can change them before Save and later, in Edit.
Why does the free calculator on the website give a different value?
The BMR calculator on MyFitnessClient's public website uses the same Mifflin-St Jeor and the same activity multipliers, but only gives resting expenditure and daily expenditure. It does not have the other formulas, the goal adjustment, the reference minimum or the macros. With the same data, BMR and TDEE come out the same.
Why does fat not go lower than 0.8 g/kg?
It is the calculator's minimum: when 25% of the target calories gives fewer grams than 0.8 g per kg of weight, the minimum applies. After applying, you can change the fat by hand in the goals.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. A study of 498 healthy adults aged 19 to 78. PubMed
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182. PubMed
- 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. PubMed
- Morton RW et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. PubMed