Health & Fitness Tools
18 calculators for body composition, daily nutrition targets, and training — built from standard, published formulas so you can see exactly how each number was reached.
None of this is medical advice. These tools apply standard published formulas (like the Mifflin-St Jeor equation for BMR, or the Navy method for body fat) to the numbers you enter — they don't know your medical history, and estimates from a formula are not a diagnosis. For anything involving a real health decision, medication, or an existing condition, talk to a clinician. See the full disclaimer for details.
Everything below runs in your browser; nothing you enter is sent to or stored on a server.
Body composition
6 toolsBMI Calculator
Check BMI against standard categories.
HLTBMR Calculator
Basal metabolic rate at rest.
HLTTDEE Calculator
Total daily energy expenditure.
HLTBody Fat Calculator
Navy and IOM method estimates.
HLTIdeal Weight Calculator
Compare several standard formulas.
HLTLean Body Mass Calculator
Body mass minus estimated fat mass.
Nutrition & intake
5 toolsMacro Calculator
Protein, carb and fat split for a target.
HLTProtein Intake Calculator
Daily protein target from weight and goal.
HLTCarb Cycling Calculator
High/low carb day split for a weekly plan.
HLTWater Intake Calculator
Daily hydration target by weight and activity.
HLTCalorie Burn Calculator
Estimate calories burned by activity.
Training & other
7 toolsHeart Rate Zone Calculator
Training zones from age and rest rate.
HLTOne Rep Max Calculator
Estimate a 1RM from a lighter set.
HLTVO2 Max Estimator
Rough aerobic fitness estimate.
HLTSleep Cycle Calculator
Optimal wake times by sleep cycle.
HLTMedication Dosage Calculator
Reference only — confirm with a pharmacist.
HLTIV Drip Rate Calculator
Reference only — for clinical professionals.
HLTPet Age Calculator
Convert a pet's age to human-equivalent years.
Frequently asked
Can I use the Medication Dosage or IV Drip Rate calculators to actually dose a patient?
No — treat both as reference-only calculators for checking arithmetic, not as clinical decision tools. Dosing decisions should always be verified against a pharmacist, a physician's order, or your facility's own protocols.
Why do the results from BMI or body fat calculators sometimes seem off for athletes?
These formulas were developed from general population data and don't account for unusually high muscle mass — a muscular athlete can show as "overweight" by BMI despite low body fat. The Body Fat and Lean Body Mass calculators are a better fit in that case.