Health Calculators
BMI Calculator
Calculate your BMI instantly. Enter your height and weight in imperial or metric units to get your Body Mass Index, weight category, and healthy weight range.
Body Fat Percentage Calculator
Calculate your body fat percentage using the US Navy Method. Enter your waist, neck, and hip measurements to estimate body fat and lean mass. Free, no sign-up required.
Calorie Deficit Calculator
Calculate exactly how many calories to eat each day to lose weight at your chosen pace. Enter your maintenance calories or let us estimate your TDEE, then pick your weekly goal. Free, browser-based, no signup.
Calories Burned Calculator
Estimate calories burned during exercise and everyday activities using MET values. Enter your weight, activity type, and duration. Supports imperial and metric. Free, no signup.
Due Date Calculator
Calculate your estimated due date from your last menstrual period. See your current week of pregnancy, trimester, and key milestones. Based on Naegele's rule. Free, no sign-up.
Heart Rate Zone Calculator
Calculate your maximum heart rate and all 5 heart rate training zones — fat burn, cardio, peak, and more. Free heart rate zone calculator by age and resting heart rate.
Ideal Weight Calculator
Calculate your ideal body weight using four proven formulas: Hamwi, Devine, Robinson, and Miller. Enter your height and sex for an instant ideal weight range in lbs or kg.
IV Drip Rate Calculator
Calculate IV drip rate in drops per minute (gtt/min) or flow rate in mL per hour for gravity and infusion pump setups. Includes drop factor selection and dosage-by-weight calculations for nursing students and healthcare professionals.
Macronutrient Calculator
Calculate your ideal daily macronutrient targets — protein, carbohydrates, and fat — based on your TDEE, body goal, and diet preference. Free macro calculator, no sign-up.
Ovulation Calculator
Calculate your ovulation date and fertile window based on your last menstrual period and average cycle length. Identify your most fertile days to help plan or avoid pregnancy. Free and private — nothing is sent to a server.
Pregnancy Weight Gain Calculator
Calculate your recommended pregnancy weight gain based on pre-pregnancy BMI and current week. Based on ACOG and IOM guidelines. Includes week-by-week tracking chart. Free, private, browser-based.
Running Pace Calculator
Calculate your running pace, estimated finish time, or distance covered. Supports miles and kilometers and common race distances from 5K to marathon. Free, instant, browser-based running calculator.
Sleep Calculator
Calculate the ideal bedtime or wake-up time based on 90-minute sleep cycles. Get personalized sleep schedule suggestions to wake up refreshed. Free, instant, no signup.
TDEE Calculator
Calculate your Total Daily Energy Expenditure (TDEE) and daily calorie needs. Find how many calories to eat for weight loss, maintenance, or muscle gain based on your stats and activity level.
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio (WHR) and see your cardiovascular health risk category. Enter waist and hip measurements in inches or centimeters. Free, instant, browser-based.
Water Intake Calculator
Calculate your daily water intake needs based on your weight, activity level, and climate. Get personalized hydration recommendations in oz, cups, and liters. Free online tool.
About These Health Calculators
These free health calculators help you understand your body's numbers — from whether your weight falls in a healthy range to how many calories you need each day to reach your goals, how much water to drink, and what heart rate zones to train in. All calculators support both imperial (lbs, feet/inches) and metric (kg, cm) units.
All calculators run entirely in your browser. Nothing you enter is sent to a server or stored anywhere.
Tools in This Category
- BMI Calculator — Calculate your Body Mass Index, see your weight category, and find your healthy weight range for your height.
- Body Fat Percentage Calculator — Estimate your body fat percentage using the U.S. Navy circumference method with just a tape measure. See your lean mass, fat mass, and fitness category.
- Ideal Weight Calculator — Run four proven medical formulas (Hamwi, Devine, Robinson, Miller) to find the ideal weight range for your height and sex.
- TDEE Calculator — Calculate your Total Daily Energy Expenditure and get daily calorie targets for weight loss, maintenance, or muscle gain.
- Macronutrient Calculator — Split your daily calorie target into protein, carbohydrate, and fat grams based on your goal and diet preference (balanced, low-carb, keto, high-protein, or low-fat).
- Water Intake Calculator — Get a personalized daily hydration target in ounces, cups, liters, and bottles based on your weight, activity level, and climate.
- Heart Rate Zone Calculator — Find your five heart rate training zones for fat burn, cardio, threshold, and peak. Supports the standard, Tanaka, and Karvonen formulas.
- Due Date Calculator — Estimate your pregnancy due date and key milestones from your last menstrual period or conception date.
Important Disclaimer
These calculators are informational tools based on widely used formulas (such as the Mifflin-St Jeor equation for BMR, the standard WHO BMI categories, and the U.S. Navy body fat method). They are not a substitute for advice from a qualified healthcare provider. Individual results vary based on factors these formulas cannot account for, including medical conditions, medications, body composition, and activity patterns.
How to Use These Calculators Together
Each calculator answers a specific question, and they're most powerful when used together as a system:
- Start with BMI and Body Fat. BMI gives you a quick weight-to-height snapshot; body fat percentage tells you what that weight is actually made of. Athletes often have a high BMI but healthy body fat.
- Find a realistic target. The Ideal Weight Calculator gives you a science-based range — not a single number — to aim for based on four clinical formulas.
- Calculate your energy needs. The TDEE Calculator tells you exactly how many calories you burn per day. This is the foundation of any effective nutrition plan.
- Break calories into macros. The Macronutrient Calculator splits your calorie target into daily protein, carb, and fat targets matched to your goal and dietary preference.
- Optimize your training. The Heart Rate Zone Calculator ensures your workouts are at the right intensity — whether you're building aerobic base in Zone 2 or pushing VO₂ max in Zone 5.
- Stay hydrated. The Water Intake Calculator gives you a daily fluid target adjusted for your body weight, activity, and climate.
How to Use These Calculators
Each calculator is designed to answer one specific question. For best results:
- Use accurate, current measurements — weigh yourself in the morning before eating for the most consistent results.
- For body fat measurements, use a flexible tape measure and follow the measurement instructions exactly — small errors in technique can shift the result by 1–2%.
- Choose the activity multiplier honestly for TDEE — most people are more sedentary than they think.
- Use the results as a starting point, track your actual progress over 2–3 weeks, and adjust from real-world data rather than solely from calculated estimates.