Use our BMI Calculator to determine your Body Mass Index and understand where you fall on the weight spectrum. Whether you're monitoring your health, starting a fitness journey, or working with a healthcare provider, knowing your BMI provides a quick snapshot of your weight relative to your height. Enter your height and weight to see your BMI score, weight category (underweight, normal, overweight, or obese), and your healthy weight range. Our calculator uses the standard BMI formula recognized by healthcare professionals worldwide, giving you the same results your doctor would calculate. Understanding your BMI helps you set realistic weight goals and track progress over time. While BMI isn't perfect—it doesn't account for muscle mass or body composition—it remains the most widely used screening tool for weight-related health risks due to its simplicity and strong correlation with health outcomes for most people.
Saved Presets is a Supporter feature.
Tool History is a Supporter feature.
Tool Notes is a Supporter feature.
Choose between metric (kg/cm) or imperial (lbs/ft/in).
Input your weight in kilograms or pounds.
Input your height in centimeters or feet and inches.
See your BMI value, category, and healthy weight range.
Body Mass Index (BMI) is a simple calculation using height and weight that estimates body fat and assesses health risks related to weight. Developed in the 1830s by Belgian mathematician Adolphe Quetelet, BMI became the standard screening tool because it's easy to calculate, doesn't require expensive equipment, and correlates reasonably well with body fat percentage for most adults. BMI works by comparing your weight to your height squared, creating a number that indicates whether you're underweight, normal weight, overweight, or obese. The formula adjusts for height, recognizing that taller people naturally weigh more than shorter people even at healthy body compositions. Healthcare providers use BMI as a screening tool, not a diagnostic tool. A high BMI suggests you may have excess body fat, which increases risk for conditions like heart disease, diabetes, high blood pressure, and certain cancers. However, BMI alone doesn't diagnose health—it identifies who should undergo further assessment.
The calculator uses the standard BMI formula: BMI = weight (kg) / height² (m²). For imperial units, we convert pounds to kilograms (÷ 2.205) and inches to meters (× 0.0254) before calculating. For example, someone who is 5'10" (70 inches / 1.778 meters) and weighs 170 pounds (77.1 kg) has a BMI of: 77.1 / (1.778²) = 77.1 / 3.16 = 24.4, which falls in the "Normal weight" category.
The World Health Organization established BMI categories based on mortality and morbidity data from millions of people. Underweight (BMI < 18.5) indicates insufficient body mass, potentially signaling malnutrition, eating disorders, or underlying health conditions. Risks include weakened immune system, osteoporosis, and fertility issues. Normal weight (BMI 18.5-24.9) represents the healthiest range associated with lowest mortality rates and lowest risk for weight-related diseases. Most people in this range have appropriate body fat levels for optimal health. Overweight (BMI 25-29.9) indicates excess body weight that may lead to health problems if maintained long-term. Risks increase gradually—someone with BMI 25 has lower risk than someone with BMI 29. Obese (BMI ≥ 30) represents significant excess body fat associated with substantially elevated health risks. Obesity is further categorized into Class I (30-34.9), Class II (35-39.9), and Class III (≥ 40), with risks increasing at each level.
Our calculator determines your healthy weight range based on BMI 18.5-24.9—the range associated with optimal health outcomes. For someone 5'10" tall, the healthy range is 129-174 pounds. This 45-pound range recognizes that healthy body composition varies between individuals based on frame size, muscle mass, and body type. If your current weight exceeds the healthy maximum, the calculator shows pounds to lose to reach the top of your healthy range. If your weight falls below the healthy minimum, it shows pounds to gain to reach the bottom of your range. These are targets, not requirements—work with healthcare providers to set appropriate personal goals.
Select your preferred unit system—metric (kg/cm) or imperial (lbs/ft). Enter your height in feet and inches or centimeters. Be as accurate as possible—even one inch can change your BMI by 1-2 points. Measure height without shoes, standing straight against a wall. Enter your current weight in pounds or kilograms. Use your morning weight after using the bathroom but before eating for most consistent results. Weight fluctuates 2-5 pounds daily due to water retention and food volume, so don't obsess over daily changes. Click calculate to see your BMI, weight category, and healthy weight range. Compare your BMI to the WHO categories and consider whether your classification aligns with how you feel physically.
Sarah is 5'4" (64 inches), weighs 150 pounds, and lifts weights 5 days/week with visible muscle definition. Online forums say her BMI is "too high" but she feels healthy and strong. - Input: 64 inches, 150 lbs, 28, Female - Result: BMI 25.7 (Overweight), Healthy range: 108-145 lbs, Weight to lose: 5 lbs Sarah's BMI technically classifies her as overweight, but this likely reflects muscle mass rather than excess fat. Athletes, bodybuilders, and very muscular individuals often have "high" BMI despite low body fat. Her doctor measures body fat percentage (18%, excellent for women) and confirms she's healthy. BMI fails for muscular builds—body composition measurements are more appropriate.
David is 6'0" (72 inches), weighs 140 pounds, and is recovering from a lengthy illness that caused significant weight loss. He was 180 pounds before illness and wants to regain weight healthily. - Input: 72 inches, 140 lbs, 52, Male - Result: BMI 19.0 (Normal weight), Healthy range: 137-185 lbs, Weight to gain: 0 lbs David's BMI of 19.0 technically falls in normal range, but just barely (0.5 points above underweight). While not clinically underweight, he lost 40 pounds and feels weak. His doctor recommends gaining 20-30 pounds through strength training and increased calorie intake to restore muscle mass and strength. BMI shows he's "normal" but doesn't capture his significant muscle loss.
Jennifer is 5'5" (65 inches), weighs 260 pounds, and is 42 years old. She has type 2 diabetes, sleep apnea, and joint pain. Her doctor discusses bariatric surgery eligibility. - Input: 65 inches, 260 lbs, 42, Female - Result: BMI 43.2 (Obese Class III), Healthy range: 111-150 lbs, Weight to lose: 110 lbs Jennifer's BMI of 43.2 indicates Class III (severe) obesity, typically the threshold for bariatric surgery consideration along with obesity-related health conditions. Losing 110 pounds seems overwhelming, but her doctor explains even 50-60 pound loss (getting BMI under 35) would significantly improve health conditions. Weight loss surgery helps achieve 60-70% excess weight loss when diet and exercise alone haven't succeeded.
No—BMI has significant limitations. It doesn't distinguish muscle from fat, so very muscular people (athletes, bodybuilders) may have "overweight" or "obese" BMI despite low body fat. It doesn't account for bone density, body frame, or fat distribution (belly fat is riskier than hip/thigh fat). Elderly people may have "normal" BMI but high body fat due to muscle loss. BMI also doesn't adjust well for certain ethnicities—Asian populations face health risks at lower BMI thresholds than Caucasians. Use BMI as one screening tool among many, not a definitive health measure.
