Weight Calculator
Use this calculator to estimate your BMI, a healthy weight range, and an ideal body weight estimate based on height.
Note: BMI and ideal weight formulas are screening tools, not medical diagnoses.
Why learning to calculate weight matters
When people search for “calculate weight,” they often want one simple answer. In reality, weight can be looked at from several useful angles. Your current scale reading is one number, but it doesn’t automatically tell you whether that number is healthy for your height, body composition, goals, or age.
A better approach is to use a few practical calculations together. That is why this page combines body mass index (BMI), healthy weight range, and ideal body weight estimate. Used together, these numbers give a clearer picture than any single metric on its own.
What this calculator gives you
- BMI: A quick ratio of your body weight to your height.
- BMI category: Underweight, normal, overweight, or obesity class ranges.
- Healthy weight range: Estimated range based on BMI 18.5 to 24.9.
- Ideal body weight estimate: A classic formula-based target (Devine formula).
The formulas behind the calculator
1) BMI formula
BMI is calculated as weight divided by height squared:
- Metric: BMI = kg / (m²)
- Imperial conversion is done first (lb to kg, ft/in to cm), then the same formula is used.
Typical BMI categories:
- Underweight: below 18.5
- Normal weight: 18.5–24.9
- Overweight: 25.0–29.9
- Obesity Class I: 30.0–34.9
- Obesity Class II: 35.0–39.9
- Obesity Class III: 40+
2) Healthy weight range by height
The tool uses your height and computes the body weight that corresponds to BMI 18.5 and 24.9. This creates a practical “healthy range” benchmark. It’s a common public health method for quick screening.
3) Ideal body weight estimate (Devine)
The ideal body weight estimate shown here uses the Devine formula, one of the most common formula-based methods:
- Male: 50 kg + 2.3 kg for each inch over 5 feet
- Female: 45.5 kg + 2.3 kg for each inch over 5 feet
This is an estimate—not a strict rule—and should be interpreted with context.
How to use this calculator correctly
- Select your unit system (metric or imperial).
- Enter your height and current weight.
- Select sex for the ideal-weight estimate.
- Click Calculate Weight Metrics.
- Review BMI, healthy range, and ideal weight together.
Try not to over-focus on one decimal place. What matters most is the trend over time and whether your habits are moving you toward better health outcomes.
Important limitations to remember
No calculator can fully describe health by itself. Use these numbers as guidance, not judgment.
- BMI does not measure body fat directly. Very muscular people may have high BMI with low fat.
- Body composition matters. Waist circumference and strength levels add critical context.
- Fluid shifts affect weight. Sodium intake, hydration, stress, and sleep can move scale weight quickly.
- Age and medical history matter. Health decisions should consider the full clinical picture.
If your goal is to lose or gain weight
For gradual fat loss
- Use a modest calorie deficit.
- Prioritize protein and fiber-rich foods.
- Strength train 2–4 times per week.
- Track weekly averages, not just daily fluctuations.
For healthy weight gain
- Use a small calorie surplus.
- Lift progressively and consistently.
- Aim for high-quality, nutrient-dense meals.
- Monitor body measurements and strength, not just scale weight.
Frequently asked questions
What is a “good” BMI?
For most adults, a BMI of 18.5 to 24.9 is considered a normal range. But athletic build, age, and body composition can change how useful that number is for an individual.
How often should I weigh myself?
Most people do well with 3–7 weigh-ins per week and then using a weekly average. Daily numbers can bounce due to water and digestion, even when fat loss is happening.
Should I target ideal body weight exactly?
Not necessarily. Formula-based ideal weight is a reference point. A sustainable and healthy range—combined with strong habits and good lab/health markers—is usually better than chasing one exact number.
Bottom line
If you want to calculate weight in a meaningful way, combine metrics rather than relying on one result. Start with BMI and healthy range, compare with ideal-weight estimates, and then make practical changes in nutrition, movement, sleep, and consistency.
Use the calculator at the top whenever your measurements change. Small improvements over months are far more powerful than quick, extreme changes.