Free tools • no account required
Calculate calories, body measurements, hydration, and pregnancy dates—then see the formula, assumptions, limitations, and practical next step.
Calculators
Each tool stays focused on one question and keeps results hidden until valid information is entered.
Get a practical starting estimate for calories and macros—plus the context needed to adjust it without treating a formula like a prescription.
Use calculator BMICalculate body mass index in U.S. or metric units, then interpret the number as a broad screening measure—not a diagnosis.
Use calculator EnergyEstimate the calories your body may use at rest before walking, working, training, and digestion are added.
Use calculator HydrationEstimate fluids in liters, ounces, cups, and milliliters—then adjust for the factors a simple formula cannot measure.
Use calculator Body compositionUse a Navy-style circumference formula for a repeatable estimate that is most useful for tracking a trend.
Use calculator Body compositionCompare waist circumference with height to add body-fat distribution context beyond body weight alone.
Use calculator Pregnancy datingEstimate the pregnancy timeline using the information you have, while keeping the result separate from an official clinical due date.
Use calculatorHow it works
Enter information in U.S. or metric units. Validation catches unrealistic or incomplete entries.
Read the formula, worked examples, common mistakes, and factors that may change the estimate.
Treat the output as education and planning—not a diagnosis, prescription, or replacement for professional care.
Featured guides
These guides answer the questions most calculators leave unresolved.
Learn how daily calorie needs are estimated for maintenance, weight loss, or gain—and how to adjust the estimate using your real trend.
Read guide Calories & macrosChoose a realistic calorie-calculator activity multiplier using work, steps, training, recovery, and examples for seated and physical jobs.
Read guide Body compositionUse a flexible tape, repeatable body landmarks, correct tension, and consistent timing for body-fat and waist-to-height estimates.
Read guide HydrationPlan hydration for outdoor labor, heat, humidity, protective clothing, and prolonged sweating while recognizing heat-illness warning signs.
Read guide Pregnancy datingLearn how clinicians estimate due dates from LMP, conception, early ultrasound, and IVF transfer timing—and why the date may change.
Read guide BMILearn why BMI cannot measure body fat, distinguish muscle, locate fat, or diagnose individual health—and which measurements can add context.
Read guideResponsible use
WellnessCalcs tools process entries in the browser and provide general educational estimates. They cannot review symptoms, medication, medical history, laboratory results, pregnancy health, or individual nutrition needs.
Use professional guidance for pregnancy care, children, eating-disorder history, chronic disease, fluid restrictions, unexplained weight change, or any result that conflicts with medical advice.
Read our editorial process