Calculation sources
Where the numbers come from
No number in Swiip is asked of an AI. Every calorie, macro and load calculation comes from the published equations below. We also wrote down why we picked each one.
Last updated: 31 August 2026
Basal metabolic rate (BMR)
Mifflin-St Jeor
Used when your body fat percentage is unknown. It estimates resting energy expenditure from height, weight, age and sex.
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. “A new predictive equation for resting energy expenditure in healthy individuals.” The American Journal of Clinical Nutrition, 1990;51(2):241–247. doi:10.1093/ajcn/51.2.241
Katch-McArdle
Used when your body fat percentage is known (from photo analysis or a value you entered): because it accounts for lean mass directly, it tells apart two people of the same weight with different composition.
McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. 8th edition. Wolters Kluwer, 2015.
Total daily energy expenditure (TDEE)
BMR is multiplied by a physical activity level (PAL) factor determined by your job and training frequency.
FAO/WHO/UNU. Human Energy Requirements: Report of a Joint FAO/WHO/UNU Expert Consultation. Roma, 2004. fao.org
Why we show a range and not a single number: the reported standard error of Mifflin-St Jeor is around 10%, and the activity factor is itself an estimate. Together, your real expenditure can be a few hundred calories above or below the calculated value. Writing a single number would promise a precision that does not exist.
Body fat estimation
With no photo and no circumference measurements, body fat is estimated from body mass index. This is the coarsest method, which is why the result is always shown as a range.
Deurenberg P, Weststrate JA, Seidell JC. “Body mass index as a measure of body fatness: age- and sex-specific prediction formulas.” British Journal of Nutrition, 1991;65(2):105–114. doi:10.1079/BJN19910073
Protein and fat targets
Protein is 2.0 g per kilogram of lean mass, and 2.2 g while in a calorie deficit. In a deficit, high protein is the strongest nutritional lever against muscle loss. Fat never goes below 0.6 g per kilogram of body weight.
Jäger R, Kerksick CM, Campbell BI, ve ark. “International Society of Sports Nutrition Position Stand: protein and exercise.” Journal of the International Society of Sports Nutrition, 2017;14:20. doi:10.1186/s12970-017-0177-8
Hector AJ, Phillips SM. “Protein Recommendations for Weight Loss in Elite Athletes.” International Journal of Sport Nutrition and Exercise Metabolism, 2018;28(2):170–177. doi:10.1123/ijsnem.2017-0273
The limit on the calorie deficit
The deficit never exceeds a set share of daily expenditure. Fast weight loss brings muscle loss, a drop in resting metabolism and impaired recovery with it.
Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. “Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes.” International Journal of Sport Nutrition and Exercise Metabolism, 2011;21(2):97–104. doi:10.1123/ijsnem.21.2.97
Tek tekrar maksimum (1RM) tahmini
Estimated from the weight you lifted and the number of repetitions. Because the estimate degrades quickly above 12 repetitions, we cap the input at 12.
Epley B. “Poundage Chart.” Boyd Epley Workout. Body Enterprises, Lincoln, NE, 1985.
LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. “The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift.” Journal of Strength and Conditioning Research, 1997;11(4):211–213.
Weekly set volume
Weekly sets per muscle group are set by training age and increase gradually over the weeks. The upper bounds follow the range where the volume-to-gain relationship flattens and recovery starts to suffer.
Schoenfeld BJ, Ogborn D, Krieger JW. “Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis.” Journal of Sports Sciences, 2017;35(11):1073–1082. doi:10.1080/02640414.2016.1210197
American College of Sports Medicine. “Progression Models in Resistance Training for Healthy Adults.” Medicine & Science in Sports & Exercise, 2009;41(3):687–708. doi:10.1249/MSS.0b013e3181915670
Bunlar birer tahmin
Every equation above is an estimate derived from population averages; your real values may differ. Swiip is not a medical device, does not diagnose and does not prescribe treatment. If you have a health condition or take medication, discuss your nutrition and training plan with your doctor.
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