About FitWijzr
Clear calculators, no miracle products.
FitWijzr is a Belgian project that helps athletes get stronger and avoid injuries, with calculators, explained exercises and nutrition knowledge that holds up.
Who is behind it?
FitWijzr was created in Belgium by Finn Inghelbrecht. The calculators, the exercises and the calculation of your personal program are free. An account is optional: it saves your profile on every device.
Guidelines, not medical advice
The calculators give a grounded estimate, not a diagnosis. FitWijzr does not replace a doctor, dietitian or physiotherapist. If you have a condition or pain, talk to your healthcare provider first.
Every result explained
For each calculator you can read which formula is behind it, with a worked example and the limits of the estimate.
No miracle products
For supplements and nutrition we look at what the evidence says, even when that means something does not work.
How the calculators work
One line per calculator. Click through for the full explanation with an example.
- BMI Calculator
Weight divided by height squared, with the WHO categories for adults.
- Calorie Calculator
Resting metabolism with the Mifflin-St Jeor formula, multiplied by an activity factor. Protein at 1.8 to 2 g per kilo, fat about a quarter of your calories.
- 1RM Calculator
The Epley formula: weight × (1 + reps ÷ 30). Most accurate at 3 to 8 reps.
- Water Calculator
A rule of thumb of 33 ml per kilo, plus 400 ml per half hour of training, with a small extra for warm weather and a lot of caffeine.
- Heart Rate Zones
Maximum heart rate by Tanaka (208 − 0.7 × age) or Fox (220 − age), zones via the Karvonen method using your resting heart rate.
- Protein Calculator
A guideline in grams per kilo of body weight, depending on your goal and eating pattern, spread over your eating occasions.
- Pace Calculator
Your pace per kilometer and finish time from distance and time, with a prediction for other distances.
Sources
The research and guidelines the calculators and texts are based on.
- BMIWorld Health Organization (2000). Obesity: preventing and managing the global epidemic. WHO Technical Report Series 894.
- CaloriesMifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51(2):241–247.
- 1RMEpley B (1985). Poundage chart. In: Boyd Epley Workout. Lincoln, NE: Body Enterprises.
- Heart rateTanaka H, Monahan KD, Seals DR (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology 37(1):153–156.
- Heart rateFox SM, Naughton JP, Haskell WL (1971). Physical activity and the prevention of coronary heart disease. Annals of Clinical Research 3(6):404–432.
- Heart rateKarvonen MJ, Kentala E, Mustala O (1957). The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae 35(3):307–315.
- ProteinMorton RW et al. (2018). 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. British Journal of Sports Medicine 52(6):376–384.
- ProteinJäger R et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition 14:20.
- HydrationSawka MN et al. (2007). American College of Sports Medicine position stand: exercise and fluid replacement. Medicine & Science in Sports & Exercise 39(2):377–390.
- Training and injury preventionAmerican College of Sports Medicine (2009). Position stand: progression models in resistance training for healthy adults. Medicine & Science in Sports & Exercise 41(3):687–708.
All formulas are estimates. Your actual values may differ.
Found a mistake or a better source?
See something that is not right, or know research we should use? Let us know. We update calculators and texts when the sources call for it.