OKTO How many calories do I need per day?
Your calories per day are your basal metabolism times an activity factor from 1.2 to 1.9, then adjusted for your goal. For example, a moderately active 35-year-old woman at 150 lb and 5 ft 5 in burns about 2,133 kcal a day.
Free, no sign-up. The math runs in your browser: nothing is sent anywhere.
these calculations are built into OKTO fit, for every client
- Age, sex, height and weight come from the client's file.
- Calorie and macro targets go onto the client's meal plan in one click.
- The result is saved to the client's file, with the date.
- Seven calculators with their sources: calories, one-rep max, heart rate zones, body fat percentage, water and protein, load progression and BMI.
Nothing is saved to the file without the client's health consent. OKTO Fit costs $29.99 a month plus taxes, no matter how many clients you have.
how the calculation works
The calculation has three steps: basal metabolism, total expenditure, then the target for your goal.
10 × kg + 6.25 × cm - 5 × age - 161
That's the Mifflin-St Jeor formula for a woman. For a man, the constant is +5 instead of -161. With no sex declared, the calculation uses the average of the two, -78.
Katch-McArdle: 370 + 21.6 × lean mass (kg)
Katch-McArdle starts from lean mass, meaning your weight minus your fat. So it needs a body fat percentage.
Total expenditure = basal metabolism × activity factor
The factor runs from 1.2 (sedentary) to 1.9 (extremely active). These factors are common practice in sports nutrition; their origin varies by author. To lose or gain weight, the target subtracts or adds a difference in kcal or as a percentage. Protein is set in grams per kilo, fat as a percentage of calories, and carbs take the rest, at 4, 9 and 4 kcal per gram.
These are the same formulas and the same rounding as in OKTO Fit, so you get the same number.
its limits
- It's an estimate: two people with the same age, weight and height can burn different amounts.
- The activity factor is the biggest source of error. Your weight over two or three weeks tells you whether the target is right.
- Katch-McArdle is only as good as the body fat measurement behind it.
- Below 1,200 kcal a day for a woman or 1,500 kcal for a man, you need a health professional's supervision.
sources
- Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990, 51(2), 241-247. doi.org/10.1093/ajcn/51.2.241
- The so-called Katch-McArdle formula, published by Cunningham JJ. Body composition as a determinant of energy expenditure. Am J Clin Nutr, 1991, 54(6), 963-969. doi.org/10.1093/ajcn/54.6.963
- Harvard Health Publishing, Calorie counting made easy. health.harvard.edu
Estimate only. This is not medical advice. Pregnant, under treatment or living with a health condition? Talk to a doctor or a registered dietitian before changing how you eat.
frequently asked questions
How many calories per day to lose weight?
The calculation starts from your total expenditure and subtracts a deficit, 500 kcal by default. Without a health professional's supervision, don't go below 1,200 kcal a day for a woman or 1,500 kcal for a man.
Mifflin-St Jeor or Katch-McArdle: which one should I use?
Mifflin-St Jeor if you don't know your body fat percentage: it uses sex, age, weight and height. Katch-McArdle starts from lean mass and makes sense when your body fat percentage is measured reliably.
Which activity level should I pick?
The factor, from 1.2 to 1.9, counts all the moving you do in a day, work included. When in doubt, pick the lower level, then adjust after two or three weeks based on how your weight moves.
Why is my result different from another calculator?
Calculators don't all use the same formula, the same activity factors or the same rounding. The result is still an estimate, a starting point to adjust based on what actually happens.
What's your one-rep max?Our 1RM calculator also gives the load to use from 50 to 95%, in kg or lb.
Calculate my 1RMevery client's targets, in one place
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