Ideal Weight Calculator

Rethinking “Ideal Weight”: What We Really Mean

The phrase “ideal weight” carries baggage. It suggests there’s a perfect number on the scale that, once achieved, will unlock health, happiness, and confidence. But anyone who’s ever fixated on a goal weight knows the truth: it’s never that simple.

In reality, what we’re actually seeking is a healthy weight range—a span of weights where your body functions well, where chronic disease risk is lower, and where you feel energized and capable. This range isn’t about aesthetics or societal beauty standards. It’s about physiology.

The formulas used in ideal weight calculators—Devine, Robinson, Miller, and others—were developed by researchers studying populations to understand healthy body weight relative to height. They’re clinical tools, originally designed for things like medication dosing and nutritional assessment, not for dictating what you “should” weigh.

So when you use an ideal weight calculator, you’re not getting a verdict on your body. You’re getting data—a reference point based on population averages that can inform (not dictate) your health decisions.

The Science Behind the Formulas

Let’s break down the main formulas and where they came from:

Devine Formula (1974)

Dr. B.J. Devine created this formula to estimate lean body weight for calculating drug dosages. It’s become one of the most widely used:

• AMAB: 50 kg + 2.3 kg per inch over 5 feet
• AFAB: 45.5 kg + 2.3 kg per inch over 5 feet

For someone 5’8″ (68 inches), that’s 50 + (2.3 × 8) = 68.4 kg for AMAB, or 45.5 + (2.3 × 8) = 63.9 kg for AFAB.

Robinson Formula (1983)

A modification of Devine, adjusting the coefficients:

• AMAB: 52 kg + 1.9 kg per inch over 5 feet
• AFAB: 49 kg + 1.7 kg per inch over 5 feet

Miller Formula (1983)

Another contemporary alternative:

• AMAB: 56.2 kg + 1.41 kg per inch over 5 feet
• AFAB: 53.1 kg + 1.36 kg per inch over 5 feet

Hamwi Formula

The simplest approach:

• AMAB: 48 kg + 2.7 kg per inch over 5 feet
• AFAB: 45.5 kg + 2.2 kg per inch over 5 feet

Notice something? For the same person, these formulas give different numbers. That’s not a bug—it’s a feature. It illustrates that there’s no single “correct” ideal weight, but rather a range.

Body Frame: The Variable Most Calculators Ignore

One major limitation of height-based formulas is that they don’t account for skeletal structure. Two people of identical height can have dramatically different healthy weights based on bone size and frame.

The classic method for determining frame size is wrist circumference relative to height, or elbow breadth measurement. While imprecise, general guidelines suggest:

• Small frame: -10% adjustment to calculated ideal weight
• Medium frame: No adjustment
• Large frame: +10% adjustment to calculated ideal weight

So if a formula suggests 70 kg for medium frame, a large-framed individual might be healthiest at 77 kg, while small-framed might be 63 kg. This 14 kg difference is substantial and highlights why individual assessment matters.

What These Formulas Don’t Tell You

As useful as ideal weight calculators can be, they have significant blind spots:

1. Muscle Mass

Athletes and physically active people often weigh more than formulas suggest due to muscle mass. Muscle is denser than fat, so a muscular person might be “above ideal weight” while having excellent body composition.

2. Body Fat Distribution

Where you carry body fat matters more than total weight. Visceral fat (around organs) is metabolically harmful, while subcutaneous fat (under skin) is relatively benign. Someone at “ideal weight” with high visceral fat can be less healthy than someone above ideal weight with better fat distribution.

3. Metabolic Health

Blood pressure, blood sugar, cholesterol, and inflammatory markers tell you more about health than weight. Some people maintain excellent metabolic health at higher weights, while others develop problems at “normal” weights.

4. Age-Related Changes

Healthy weight ranges shift with age. Older adults (60+) tend to have better health outcomes at slightly higher BMIs than younger adults. This is called the “longevity paradox”—some weight in reserve can be protective.

5. Individual Health History

Medical conditions, medications, genetics, and personal history all affect what weight is truly healthy for you. Calculators can’t account for these nuances.

Weight vs. Health: Correlation Isn’t Causation

Public health messaging often conflates weight with health, but the relationship is more complex. Yes, being at extremes—very low or very high weight—correlates with increased health risks. But within a broad range, individual variation is huge.

Research has identified the concept of “metabolically healthy” people across weight categories. Some individuals at higher weights have excellent insulin sensitivity, blood pressure, and cholesterol. Others at “normal” weight have metabolic syndrome.

What seems to matter more than weight per se are:

• Physical activity: Fitness is protective independent of weight
• Nutrition quality: What you eat matters more than how much
• Sleep: Poor sleep disrupts metabolism at any weight
• Stress: Chronic stress damages health regardless of size
• Genetics: Family history influences disease risk

This isn’t to say weight doesn’t matter—it does. But it’s one variable among many, not the ultimate determinant of health.

Using Ideal Weight Calculators Responsibly

So how should you use an ideal weight calculator without falling into unhealthy thinking?

1. View It as a Range, Not a Target

If your result says 60-70 kg, understand that anywhere in this range—or even somewhat outside it—could be healthy for you. Don’t fixate on hitting the midpoint.

2. Consider the Context

Are you highly active? Muscular? Have you been stable at your current weight for years with good health markers? Then maybe your “ideal” weight is different from what the formula suggests.

3. Focus on Behaviors, Not Numbers

Instead of “I need to weigh X kg,” reframe as “I want to eat more vegetables,” “I want to strength train twice a week,” or “I want to reduce stress.” Healthy behaviors often lead to a healthy weight, but chasing a number can lead to disordered patterns.

4. Check In With Healthcare Providers

If you’re considering weight changes, discuss with a doctor or registered dietitian who can assess your individual health picture—bloodwork, body composition, family history, lifestyle.

5. Watch for Red Flags

If using an ideal weight calculator triggers obsessive thoughts, extreme restriction, or emotional distress, step back. These tools should inform, not control.

The Weight Stigma Problem

We can’t discuss ideal weight without acknowledging weight stigma—the systematic prejudice and discrimination people in larger bodies face in healthcare, employment, and daily life.

Weight stigma itself is a health hazard. Experiencing discrimination leads to:

• Avoidance of medical care (which worsens health outcomes)
• Increased stress and cortisol (which promotes weight gain)
• Disordered eating patterns
• Mental health challenges

Ironically, weight stigma likely worsens the very health problems it claims to address. Compassionate, weight-neutral approaches focused on health behaviors often produce better outcomes than weight-centric interventions.

Ideal weight calculators, when misused, can reinforce stigma by suggesting there’s a “correct” weight everyone should achieve. The reality is that healthy people exist across a wide spectrum of sizes.

Practical Steps Toward Your Healthiest Self

If you’re using this calculator to guide health decisions, here are evidence-based strategies that work regardless of where you fall on the weight spectrum:

Nutrition

• Eat more whole foods—vegetables, fruits, whole grains, legumes, nuts
• Limit ultra-processed foods high in added sugar, salt, and industrial fats
• Don’t villainize foods—deprivation often backfires
• Pay attention to hunger and fullness cues

Movement

• Aim for 150+ minutes of moderate activity weekly
• Include strength training 2-3 times per week
• Find activities you enjoy, not just what burns calories
• Movement is for health and joy, not punishment

Sleep

• Prioritize 7-9 hours nightly
• Poor sleep disrupts hunger hormones and metabolism

Stress Management

• Chronic stress promotes visceral fat accumulation
• Practice stress-reduction techniques that work for you

Medical Care

• Regular check-ups with blood pressure, blood sugar, cholesterol screening
• Don’t avoid the doctor due to weight concerns
• Advocate for weight-neutral care if needed

The Bottom Line: Health Is Personal

An ideal weight calculator can provide useful information—a reference point, a reality check, a conversation starter with your doctor. What it can’t do is tell you definitively what you should weigh or whether you’re healthy.

Your healthiest weight is the weight at which:

• Your body feels strong and capable
• Your bloodwork looks good
• You’re free from obsessive thoughts about food and weight
• You can engage in activities you value
• You feel like yourself

That weight might align with what a formula predicts. It might not. And that’s okay.

Use this calculator as one data point among many. Combine it with how you feel, what your lab results show, and guidance from healthcare providers who see you as a whole person, not just a number on a chart.

Your body is yours. You get to define what health means for you.