Useful numbers, honestly explained.
Sixteen free calculators for nutrition, body composition, training and everyday health. Every result shows the method, its limits and the next practical step—without asking for an email address.
Calculator collections
Start with the right tool, then compare related measures and guides inside one focused topic hub.
Nutrition Calculators
Turn nutrition questions into useful starting ranges without pretending that an equation knows your body perfectly.
6 tools →02Body Composition Calculators
No single body-composition number tells the whole story. Use complementary measures, consistent technique and trends.
5 tools →03Fitness & Performance Calculators
Translate a workout into pace, intensity, capacity and load—then use the result to plan rather than judge.
5 tools →All calculators
The number takes seconds; understanding it takes minutes. Every tool is built to do both.
Calorie needs
Estimate resting metabolism, maintenance calories and a measured starting target for your goal.
Open calculator→Macro split
Turn a calorie target into practical protein, carbohydrate and fat ranges.
Open calculator→BMI
Calculate adult BMI, its screening category and the corresponding reference weight interval.
Open calculator→Body-fat estimate
Estimate body-fat percentage and lean mass from consistent tape measurements.
Open calculator→Healthy weight range
See the BMI reference interval for your height without pretending there is one perfect weight.
Open calculator→Protein needs
Estimate a useful daily protein range for maintenance, fat loss or muscle gain.
Open calculator→Water intake
Get a practical hydration starting range adjusted for body weight, exercise and heat.
Open calculator→Calorie deficit
Model a daily deficit, theoretical weekly rate and a cautious timeline to a target.
Open calculator→Waist-to-height ratio
Compare waist circumference with height as a simple central-fat screening signal.
Open calculator→Heart-rate zones
Estimate maximum heart rate and five personalised zones using resting pulse.
Open calculator→One-rep max
Estimate maximal strength and training loads from a controlled multi-rep set.
Open calculator→Running pace
Convert distance and time into pace, speed and same-pace race equivalents.
Open calculator→FFMI and lean mass
Calculate fat-free mass index from weight, height and an estimated body-fat percentage.
Open calculator→VO₂ max estimate
Estimate relative and absolute aerobic capacity from a properly performed 12-minute run.
Open calculator→Daily fibre target
Estimate a practical daily fibre target from energy intake, age and sex.
Open calculator→Activity calories
Estimate gross and net energy use for common activities with current Compendium MET values.
Open calculator→No calculator matches that search.
A calculation starts it. Tracking shows what works.
Kivawell keeps meals, macros, movement, sleep and your progress together—so a one-time calculation becomes useful data.