CalcIdeal Weight Calculator
Last updated: 2026-09-09
| Height (cm) | Gender | |
|---|---|---|
| Child | 100 | Male |
| Teen | 131.25 | Male |
| Adult (F) | 175 | Male |
| Adult (M) | 250 | Female |
| Elderly | 250 | Female |
Ideal Weight Calculator
TL;DR: To calculate your ideal weight, first convert your height to meters (e.g., 175 cm = 1.75 m), then multiply the square of your height by 18.5 for the minimum healthy weight (1.75² × 18.5 = 56.7 kg) and by 24.9 for the maximum healthy weight (1.75² × 24.9 = 76.3 kg), giving you a healthy range of 56.7–76.3 kg based on BMI, with optional Lorentz and Devine formulas for alternative reference points.
What Is the Ideal Weight Calculator?
The Ideal Weight Calculator is a health assessment tool that estimates a healthy body weight range based on your height. Rather than giving you a single, rigid number, it calculates a range between a minimum and maximum weight that is considered healthy for your specific height. This range is derived from the Body Mass Index (BMI) standards established by the World Health Organization, which define a healthy BMI as falling between 18.5 and 24.9 kg/m². The calculator also provides optional reference estimates using the Lorentz and Devine formulas, which have historically been used in clinical settings to determine "ideal" body weight for medication dosing and nutritional assessments.
This tool is essential for anyone who is starting a fitness journey, consulting with a healthcare provider about weight management, or simply curious about whether their current weight falls within a healthy range. It is particularly useful for individuals who are setting weight loss or weight gain goals and need a concrete, evidence-based target. However, it is crucial to understand that this calculator provides a general guideline, not a definitive medical diagnosis. Athletes with high muscle mass, elderly individuals, and people with significant bone density variations may find that their healthy weight falls outside this calculated range, which is why the calculator also includes the alternative Lorentz and Devine formulas for cross-reference.
The calculator addresses a common misconception: that there is a single "ideal" weight for everyone of a given height. In reality, a range of weights can be perfectly healthy for the same person, depending on factors like muscle-to-fat ratio, frame size, and age. By presenting a range alongside alternative formula estimates, this tool empowers users to make informed decisions rather than chasing an arbitrary number.
How to Use the Calculator
Using the Ideal Weight Calculator is straightforward, but accurate input is essential for meaningful results. Follow these steps to get the most accurate estimate of your healthy weight range.
- Enter your height: Locate the height input field and enter your height in centimeters (e.g., 175) or in feet and inches (e.g., 5'9"), depending on the unit selector provided. The calculator will convert this to meters automatically, but you can double-check: 175 cm equals 1.75 meters.
- Optional – Set your gender: If the calculator includes a gender selector, choose either "Male" or "Female." This setting affects the Lorentz and Devine formula calculations, as these formulas use different constants for men and women. If you prefer not to specify, the calculator will likely default to a unisex BMI-based calculation.
- Review the results: Once you click the "Calculate" button, the tool will immediately display your healthy weight range based on your height. You will see a minimum weight calculated using a BMI of 18.5 and a maximum weight calculated using a BMI of 24.9. If you enabled the optional formulas, you will also see the Lorentz and Devine reference weights displayed alongside the BMI range.
- Interpret the output: The primary result is your healthy BMI weight range. For a 175 cm tall individual, this will be approximately 56.7 kg (125 lbs) to 76.3 kg (168 lbs). If your current weight falls below the minimum, you may be underweight; if it exceeds the maximum, you may be overweight. The Lorentz and Devine values are secondary references that often produce a single number rather than a range.
Formula and Calculation Method
The Ideal Weight Calculator uses a multi-step approach built on the scientific consensus that a Body Mass Index (BMI) between 18.5 and 24.9 is associated with the lowest risk of weight-related health complications. The calculation is performed in a clear, sequential manner that is easy to follow, even without the web tool.
Step 1: Height Conversion
Your height must be in meters for the BMI formula. If you input 175 cm, the conversion is simply dividing by 100: 175 ÷ 100 = 1.75 meters. If you input feet and inches, the calculator converts to centimeters first and then to meters.
Step 2: Calculate the Healthy Weight Range
The core formula uses the BMI equation in reverse. Since BMI = weight (kg) ÷ height² (m²), we rearrange it to solve for weight: Weight = BMI × Height². To find the minimum healthy weight, use a BMI of 18.5. To find the maximum healthy weight, use a BMI of 24.9. The calculation for a 175 cm person is as follows:
Minimum weight: 18.5 × (1.75 m)² = 18.5 × 3.0625 = 56.66 kg
Maximum weight: 24.9 × (1.75 m)² = 24.9 × 3.0625 = 76.26 kg
Therefore, the healthy weight range for someone who is 175 cm tall is approximately 56.7 kg to 76.3 kg.
Step 3 (Optional): Lorentz Formula
The Lorentz formula provides a single reference weight. It uses different calculation constants depending on gender:
- For men: Ideal weight (kg) = height (cm) − 100 − [(height (cm) − 150) ÷ 4]
- For women: Ideal weight (kg) = height (cm) − 100 − [(height (cm) − 150) ÷ 2]
Using this formula for a 175 cm man: 175 − 100 − [(175 − 150) ÷ 4] = 175 − 100 − 6.25 = 68.75 kg.
Step 4 (Optional): Devine Formula
The Devine formula also generates a single number and uses gender-specific constants, though it differs from Lorentz:
- For men: Ideal weight (kg) = 50 + 2.3 × (height in inches − 60)
- For women: Ideal weight (kg) = 45.5 + 2.3 × (height in inches − 60)
For a 175 cm man (68.9 inches): 50 + 2.3 × (68.9 − 60) = 50 + 2.3 × 8.9 = 50 + 20.47 = 70.47 kg.
Notice how the BMI range (56.7–76.3 kg) is considerably broader than the single-point estimates from Lorentz (68.75 kg) and Devine (70.47 kg). The BMI range is often considered the most accurate because it reflects the diversity of healthy body compositions.
Practical Examples
To illustrate how the Ideal Weight Calculator works in real life, consider the following scenarios. Each demonstrates different inputs and explains the interpretation of the output.
| Scenario | Height Input | BMI Weight Range | Lorentz Result | Devine Result | Interpretation |
|---|---|---|---|---|---|
| Woman, 160 cm | 160 cm (1.60 m) | 47.4 kg – 63.7 kg | 54.0 kg | 52.6 kg | A healthy range of roughly 47–64 kg. All formulas are in agreement, suggesting no extreme variation in body type expectations. |
| Man, 185 cm | 185 cm (1.85 m) | 63.3 kg – 85.2 kg | 76.25 kg | 78.6 kg | A tall individual can weigh up to 85 kg and still be healthy. The Devine formula slightly exceeds the midpoint of the BMI range, showing inherent formula variance. |
| Woman, 150 cm | 150 cm (1.50 m) | 41.6 kg – 56.0 kg | 49.0 kg | 48.2 kg | A shorter individual has a narrower absolute range, emphasizing that even 5 kg can significantly impact BMI classification for people under 155 cm. |
These examples show that while the formulas produce slightly different numbers, they all fall within the broader BMI healthy range. The minimum and maximum BMI bounds provide the most practical, science-backed target for health management.
Tips for Accurate Results
To ensure the Ideal Weight Calculator provides you with the most realistic and useful data, pay attention to the following factors that can significantly affect your results.
- Double-check your height conversion: The most common error is entering height incorrectly. If you are 175 cm, ensure you are not entering 1.75 in a field that expects centimeters, or vice versa. A 5 cm error in height can shift your entire weight range by 3–5 kg, which is clinically significant.
- Understand that this is not a "model weight" range: The lower end of the BMI range (e.g., 56.7 kg for a 175 cm man) is the absolute minimum for health, not an aesthetic target. Many fashion and fitness models fall below the healthy BMI threshold, which can lead to hormonal imbalances, bone density loss, and chronic fatigue. Do not use the minimum number as your goal unless supervised by a healthcare professional.
- Take bone structure into account: The BMI range assumes an average frame size. If you have a naturally large-boned frame (wrist circumference greater than 18 cm for men or 16 cm for women), your healthy weight may be closer to the upper end of the range or even slightly above it. Conversely, small-boned individuals should aim for the lower to middle portion of the range.
- Beware of outdated formulas: Some legacy calculators still use the Hamwi formula (developed in 1964) which often produces weights 5–10 kg below modern BMI standards. This calculator uses the evidence-based BMI range (18.5–24.9) as its primary output, with Lorentz and Devine included only as historical references for clinical comparison. Always prioritize the BMI range over any single-number formula.
- Recognize that muscle weighs more than fat: If you are highly active or lift weights, your actual healthy weight may exceed the BMI maximum. The BMI range is population-based, not athlete-specific. If your body fat percentage is under 15% (men) or 22% (women), a weight above the BMI range may still be metabolically healthy.
Frequently Asked Questions
1. Is the ideal weight the same for a 65-year-old as for a 30-year-old of the same height?
No, it is not exactly the same, though the calculator does not automatically adjust for age. Research shows that healthy BMI ranges shift upward with age. For adults over 65, a BMI between 23 and 27 is often associated with the lowest mortality risk, compared to 18.5–24.9 for younger adults. This is because older adults lose lean muscle mass and bone density, so a slightly higher body weight provides a protective reserve against illness-related weight loss and frailty. If you are over 65, you should interpret the upper end of the calculator's range as fully acceptable and not strive to be near the lower end. Additionally, the Lorentz and Devine formulas do not include age variables, making them less accurate for elderly populations.
2. Am I overweight if I weigh more than the calculated maximum weight?
Not necessarily. The maximum weight in the calculator (e.g., 76.3 kg for a 175 cm man) represents the upper boundary of a normal BMI of 24.9. If you weigh slightly above this, you fall into the "overweight" BMI category (25–29.9), but this category does not automatically mean unhealthy. Multiple studies indicate that individuals in the "overweight" BMI range often have lower all-cause mortality than those in the "normal" range, provided their waist circumference is not elevated and they maintain good metabolic markers (blood pressure, cholesterol, and blood sugar). The BMI calculation does not differentiate between muscle mass and fat mass. A rugby player or a bodybuilder at 80 kg and 175 cm would have a BMI of 26.1 (overweight) yet likely have a body fat percentage below 12%. This calculator should be your starting point, not your verdict.
3. Which of the formulas (BMI range, Lorentz, or Devine) should I trust the most?
You should prioritize the BMI-derived range (18.5–24.9) as your primary reference. The World Health Organization and the National Institutes of Health base their weight guidelines on this BMI range due to the extensive epidemiological evidence linking it to the lowest incidence of cardiovascular disease, type 2 diabetes, and certain cancers. The Lorentz formula (developed in 1929) and the Devine formula (developed in 1974) were created for entirely different purposes—specifically, calculating ideal drug doses, not defining healthy weight. The Devine formula, for instance, was invented to determine digoxin dosages, not to advise the public on overall weight management. While these formulas produce useful single-point references that often fall near the center of the BMI range, they cannot replace the nuanced, range-based approach of the BMI method. Use the BMI range to set your health boundaries and the Lorentz/Devine numbers simply as a sanity check.