Ideal Weight Calculator: What Should You Actually Weigh?

Last updated: July 2026

“Ideal weight” charts have been around for decades, but most people don’t realize they’re built on different formulas that can disagree with each other by 10-15 lbs for the same person. Understanding which formula applies to you — and why “ideal” is really a range, not a single number — makes the result far more useful.

Find your range here: Ideal Weight Calculator →

Table of Contents

  1. Why “Ideal Weight” Isn’t One Number
  2. The 4 Formulas Explained
  3. How Frame Size Changes the Answer
  4. Ideal Weight vs. BMI vs. Body Fat %
  5. What to Do With Your Result
  6. Common Mistakes
  7. FAQ

1. Why “Ideal Weight” Isn’t One Number

Ideal body weight formulas were originally developed for medical purposes — primarily to estimate drug dosing in clinical settings, not as a fitness benchmark. Over time they became popularized as general “healthy weight” references, even though that was never their original purpose.

Because multiple formulas exist, each with slightly different assumptions, our calculator shows results from all four major methods side by side — giving you a range rather than a single misleading number.

2. The 4 Formulas Explained

Robinson Formula (1983): One of the most commonly cited modern adaptations, based on height with a fixed baseline weight per gender, adjusted per inch over 5 feet.

Miller Formula (1983): Similar structure to Robinson, but with slightly different baseline constants, generally producing marginally lower estimates.

Devine Formula (1974): Originally created for medical dosing calculations, this remains one of the most widely used formulas in clinical practice today.

Hamwi Formula (1964): The oldest of the four, developed for use in diabetes management, using a simple rule of thumb per inch of height above 5 feet.

Because these formulas were built decades apart with different populations in mind, they can vary by 5-15 lbs for the same height. That’s precisely why looking at all four together — as a range — is more useful than trusting any single number in isolation.

3. How Frame Size Changes the Answer

None of the four classic formulas account for frame size or bone structure, which is a real limitation. Someone with a naturally larger frame (measured by wrist circumference relative to height) will carry a healthy weight above these formulas’ output, while someone with a smaller frame may sit below it.

A simple frame-size check: measure your wrist circumference. Generally, a smaller wrist relative to height suggests a smaller frame, and vice versa. This context helps interpret your calculator result rather than take it as an absolute target.

4. Ideal Weight vs. BMI vs. Body Fat %

Metric What it measures Limitation
Ideal weight formulas Height-based weight estimate Ignores frame size, muscle mass
BMI Weight relative to height² Can misclassify muscular people
Body fat % Actual composition Requires measurement, more effort

The most complete picture comes from using these together: an ideal weight range as a rough anchor, BMI as a population-level screening tool, and body fat percentage as the most individually meaningful metric.

5. What to Do With Your Result

Treat your ideal weight range as a starting reference point, not a rigid target:

  1. Look at the range across all four formulas rather than fixating on one.
  2. Cross-check with your Body Fat Calculator result — a “high” weight with a healthy body fat percentage usually means more muscle, not excess fat.
  3. Use your Calorie Burn Calculator result to set a realistic calorie target if you’re aiming to move toward that range.
  4. Reassess every few weeks rather than chasing a single static number.

6. Common Mistakes

  • Treating the number as a strict target. These formulas produce estimates, not medical prescriptions.
  • Ignoring muscle mass. Athletes and lifters often sit well above “ideal weight” charts while being perfectly healthy.
  • Comparing across formulas without context. A 10 lb difference between Devine and Hamwi for the same height is expected, not an error.
  • Using it as the sole metric. Pairing it with body fat percentage and waist circumference gives a far more complete picture of health.

7. FAQ

Which formula is most accurate?

None is definitively "most accurate" — they were built for different original purposes. The Devine formula remains most common in modern clinical use, but viewing all four as a range is more useful than picking one.

Does this calculator account for muscle mass?

No — these formulas are height/frame-based only. Pair the result with a body fat percentage check for a fuller picture if you're muscular or very lean.

Is a higher-than-"ideal" weight automatically unhealthy?

No. Muscle mass, bone density, and frame size all affect healthy weight independent of these formulas. Body composition matters more than the scale number alone.

How often should I recheck my ideal weight range?

It only needs recalculating if your height changes (rare after adulthood) or you want to reconfirm after significant training changes affecting your frame assessment.

Find your range: Use the Ideal Weight Calculator →

Reference: CDC — Assessing Your Weight