Free Health & Fitness Calculators
Understand your body's numbers — BMI, metabolism, body fat, calories, hydration and more. Accurate, private, and free.
Last updated: June 2026
BMI Calculator
Body Mass Index with category, healthy weight range and a colour-coded scale.
Open toolBMR & Calorie Calculator
Basal metabolic rate and daily calorie targets using the Mifflin-St Jeor formula.
Open toolBody Fat Percentage
Estimate body fat with the US Navy method, plus fat mass and lean mass.
Open toolIdeal Weight Calculator
Your healthy weight range from four medical formulas at once.
Open toolCalorie Deficit Calculator
How many calories to eat daily to lose weight safely, with a timeline.
Open toolWater Intake Calculator
Daily hydration target based on weight, activity and climate.
Open toolPregnancy Due Date
Due date, week and trimester from your last period or conception date.
Open toolOvulation Calculator
Fertile window and ovulation date with a 3-month calendar view.
Open toolMacro Calculator
Daily protein, carb and fat targets for your goal, with a donut chart and food equivalents.
Open toolPeriod Tracker
Predict your next period, fertile window and PMS days, with a 3-month calendar. Private, on-device only.
Open toolChild BMI Calculator
BMI percentile for children and teens aged 2–19 using CDC growth charts, by age and sex.
Open toolCarbon Footprint Calculator
Estimate your annual CO2 from transport, flights, home energy and diet, with reduction tips.
Open toolTry these examples
Know your numbers, take charge of your health
Good health decisions start with good information. CrispToolHub's free health and fitness calculators turn your basic measurements into the numbers that actually guide weight management, nutrition and fitness — your BMI, your metabolism, your body composition, your calorie and hydration needs — all in one private place, with no sign-up and nothing uploaded.
The BMI calculator is the classic starting point, placing your weight-to-height ratio on a category scale and showing the healthy weight range for your height. To understand the energy side, the BMR and calorie calculator uses the trusted Mifflin-St Jeor equation to estimate how many calories your body burns at rest and across your activity level, then translates that into daily targets for losing, maintaining or gaining weight.
For a fuller picture of body composition, the body fat percentage calculator uses the US Navy circumference method to estimate your fat and lean mass, and the ideal weight calculator averages four respected medical formulas to suggest a healthy weight range. When your goal is fat loss, the calorie deficit calculator shows exactly how many calories to eat each day to reach your target safely, with a realistic timeline and a macro breakdown.
Rounding out the suite, the water intake calculator sets a daily hydration goal adjusted for your weight, activity and climate, while the pregnancy due date and ovulation calculators support family planning with due dates, trimesters and fertile windows. Every tool is an educational estimate, not medical advice — always consult a healthcare professional for decisions about your health. Pick a calculator above to begin.
Medical Disclaimer: These tools provide general health information for educational purposes only. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment.
How to get started
Three quick steps — no account, nothing uploaded to a server.
Choose a tool from below
Browse the tools on this page and pick the one that fits what you need.
Use it instantly — no account needed
Open it and start right away; everything runs free in your browser.
Download or copy your results
Save, copy or share your output in a click — nothing is uploaded to a server.
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FAQ
Frequently asked questions
Are these health calculators a substitute for medical advice?
No. Every tool here provides general health information for educational purposes only — useful for tracking and understanding your numbers, but not a diagnosis or treatment plan. Always consult a qualified healthcare professional for medical advice, and treat any result as a starting point for that conversation rather than a definitive figure.
Which health metrics can I calculate?
The hub covers Body Mass Index (BMI), Basal Metabolic Rate (BMR) and daily calorie needs, body fat percentage, ideal weight, the calorie deficit needed to lose weight, daily water intake, pregnancy due date, ovulation and fertile windows, and daily macros (protein, carbs and fat). Each tool explains the formula it uses and what the result means.
Do the calculators work in both metric and imperial units?
Yes. The weight and height tools let you switch between metric (kilograms and centimetres) and imperial (pounds, feet and inches), and the results are shown in the units you choose, so they work wherever you are in the world.
Which formulas do the tools use?
BMR and calorie tools use the widely trusted Mifflin-St Jeor equation; body fat uses the US Navy circumference method; ideal weight averages the Hamwi, Devine, Robinson and Miller formulas; and BMI uses the standard weight-over-height-squared formula. These are well-established estimates, though individual bodies vary.
Is my health data private?
Completely. Every calculation runs in your browser with JavaScript — the figures you enter, including weight, measurements and health details, are never uploaded, stored or shared. Nothing leaves your device.