Common health tasks
Relate adult height and weight and view the screening category limits.
Open calculator Calorie CalculatorEstimate energy needs from a population equation and activity assumption.
Open calculator Pace CalculatorConnect distance, time and pace for training planning.
Open calculator Pregnancy CalculatorEstimate obstetric dates from standard calendar assumptions.
Open calculatorHow to use these calculators
Health calculators summarize measurements with published equations. They cannot examine symptoms, confirm a diagnosis or know whether a population reference applies to an individual. Check the stated age, sex, pregnancy, training or measurement scope before interpreting a category.
Measurement technique matters. Height, waist, heart rate and food intake can vary with equipment and timing. Repeat important measurements under similar conditions and discuss concerning or unexpected results with a qualified clinician. HitEquals labels screening outputs as estimates and links reviewed guides to the source used for the equation or threshold.
Three checks that change the answer
Check the population
Adult BMI categories do not replace child percentiles, and predictive equations may exclude pregnancy or specific medical conditions.
Treat estimates as ranges
Metabolism, body composition and training response vary beyond what an equation can capture.
Escalate symptoms, not scores
Urgent or persistent symptoms require professional care regardless of a calculator result.
Before you use the answer
- Confirm the equation applies to the person and age group.
- Use consistent measurement technique and units.
- Read the limitation beside the output.
- Do not change medication or treatment from a calculator alone.
Browse all 40 health calculators
Every tool calculates in your browser. Pages marked “Reviewed guide” also include topic-specific explanations and source checks.
- BMI CalculatorReviewed guideCalculate adult body mass index, weight category and the weight range associated with BMI 18.5–24.9.
- BMR CalculatorReviewed guideEstimate adult resting energy expenditure with the Mifflin–St Jeor equation.
- TDEE CalculatorReviewed guideEstimate total daily energy expenditure from resting energy and an explicit activity factor.
- Calorie CalculatorReviewed guideEstimate adult maintenance calories and transparent intake scenarios for gradual weight change.
- Body Fat CalculatorReviewed guideEstimate adult body fat percentage from BMI, age and sex using the published Deurenberg equation.
- Macro CalculatorReviewed guideConvert a calorie target and macronutrient percentages into grams of protein, carbohydrate and fat.
- Height CalculatorReviewed guideConvert adult height or estimate a child's adult height from parental heights with the mid-parental method.
- Pregnancy CalculatorReviewed guideEstimate a due date and gestational timeline from LMP, conception or an IVF transfer date.
- Ideal Weight CalculatorReviewed guideCompare four historical adult reference-weight equations with a BMI-based range for height.
- Calories Burned CalculatorReviewed guideEstimate activity energy expenditure from body weight, duration and a published MET value.
- Pace CalculatorReviewed guideCalculate running or walking pace, speed and projected finish times from distance and elapsed time.
- Protein CalculatorReviewed guideCalculate a transparent daily protein reference from body weight, life-stage factors or a custom grams-per-kilogram target.
- Bra Size CalculatorReviewed guideEstimate a starting bra size from underbust and full-bust measurements, with US, UK and EU displays.
- Pregnancy Conception CalculatorReviewed guideEstimate conception timing from a last menstrual period or due date using transparent obstetric dating assumptions.
- Ovulation CalculatorReviewed guideEstimate ovulation, the fertile interval and upcoming cycle dates from LMP and average cycle length.
- Body Type CalculatorReviewed guideCompare shoulder, bust, waist and hip proportions using a transparent apparel-shape heuristic.
- Period CalculatorReviewed guideProject upcoming period dates and cycle days from a recorded start date, average cycle and bleeding length.
- Sleep CalculatorReviewed guidePlan an evidence-based bedtime from wake time or calculate sleep duration after latency and awake time.
- One Rep Max CalculatorReviewed guideEstimate one-repetition maximum with four published equations and build a percentage-based load table.
- Army Body Fat CalculatorReviewed guideCalculate the U.S. Army's current waist-to-height ratio and compare the superseded multi-site body-fat equation.
- BAC CalculatorReviewed guideEstimate blood alcohol concentration from beverage strength, serving size, body weight and elapsed time.
- Pregnancy Weight Gain CalculatorReviewed guideCompare current singleton-pregnancy weight gain with BMI-based guideline ranges by gestational week.
- Carbohydrate CalculatorReviewed guideConvert a daily calorie target and carbohydrate percentage into grams and calories from carbohydrate.
- Lean Body Mass CalculatorReviewed guideEstimate adult lean body mass with the sex-specific Boer height-and-weight equations.
- Healthy Weight CalculatorReviewed guideCalculate the adult weight interval corresponding to BMI 18.5 through 24.9 for a stated height.
- Target Heart Rate CalculatorReviewed guideEstimate an age-predicted maximum heart rate and Karvonen target zone using resting heart rate.
- Fat Intake CalculatorReviewed guideConvert a daily calorie target and fat percentage into grams and calories from fat.
- GFR CalculatorReviewed guideEstimate adult eGFR with the race-free 2021 CKD-EPI creatinine equation published by NIDDK.
- Body Surface Area CalculatorReviewed guideEstimate body surface area with the Mosteller height-and-weight formula.
- Low BMI and Eating-Disorder Screening ReferenceReviewed guideCalculate adult BMI and explain why BMI cannot diagnose anorexia nervosa or any eating disorder.
- Weight Watcher Points CalculatorReviewed guideProvide an unofficial transparent legacy-style food-point estimate from nutrition-label values.
- Overweight CalculatorReviewed guideCalculate adult BMI and the weight difference from the BMI 25 screening boundary.
- Waist-to-Height Ratio CalculatorReviewed guideCalculate waist circumference divided by height using matching units.
- Waist-to-Hip Ratio CalculatorReviewed guideCalculate waist circumference divided by hip circumference using matching units.
- VO₂ Max CalculatorReviewed guideEstimate aerobic capacity from distance covered in a 12-minute Cooper field test.
- Race Time PredictorReviewed guideProject an equivalent race time with the Riegel endurance equation.
- Hydration CalculatorReviewed guideBuild a planning estimate from body weight, exercise duration and measured sweat loss.
- Creatinine Clearance CalculatorReviewed guideEstimate adult creatinine clearance with the Cockcroft–Gault equation from age, weight, sex and serum creatinine.
- Corrected Calcium CalculatorReviewed guideApply a conventional albumin-adjustment equation to total serum calcium.
- Steps to Miles CalculatorReviewed guideConvert steps to miles and kilometers, or miles to steps, using your own step length and walking pace.
Frequently asked questions
Can these calculators diagnose a condition?
No. They provide mathematical estimates or screening context and cannot replace clinical evaluation.
Why might two health calculators disagree?
They may use different validated equations, populations, thresholds or activity assumptions.
Are more decimal places more accurate?
No. Display precision cannot remove biological variation or measurement error.
What should I do with an unexpected result?
Check the inputs and scope, repeat the measurement if appropriate and discuss concerns with a qualified health professional.
Reference starting points
Individual reviewed guides cite the equation or standard used by that calculator. These authorities provide broader context for this collection.