GLP-1 Ideal Weight Calculator
Estimate ideal body weight (IBW) and healthy BMI weight range by height
This calculator estimates ideal body weight using several widely used IBW formulas and also shows the healthy weight range based on BMI (18.5–25). Use it as a reference point for goal-setting and discussions with your clinician—especially if you're on GLP‑1 therapy and want to protect muscle while losing weight.
Calculate Your Ideal Weight
How to Use This Calculator
Follow these steps to estimate a reference weight range you can use for goal-setting.
Enter your details
Select your sex assigned at birth and add your height (ft/in or cm). IBW equations are height-based and use different constants for female and male physiology.
Optionally add your current weight
This lets you see your current BMI category and how far each estimate is from where you are today.
Click Calculate
You'll see multiple IBW estimates plus a healthy BMI weight range, all at once.
Use the range to set a realistic goal
Treat the results as reference points. If you're on GLP‑1 therapy, a clinician can help you choose a goal that supports health and lean mass.
Frequently Asked Questions
Quick answers about how the calculator works and what the results mean.
What is this Ideal Weight Calculator?
It estimates "ideal body weight" using several well-known IBW formulas (Hamwi, Devine, Robinson, Miller) and also shows a healthy weight range based on BMI 18.5–25. These are reference estimates—not a diagnosis or a rule you must follow.
What formulas does it use (and where do they come from)?
We use four classic IBW equations that estimate weight from height with sex-specific constants:
- Hamwi (1964) — one of the earliest IBW formulas
- Devine (1974) — widely used in clinical drug dosing
- Robinson (1983) — slightly more conservative estimates
- Miller (1983) — balanced between high and low estimates
All formulas use a baseline at 5 feet (60 inches) and add a sex-specific increment per inch above that.
What is the "Healthy BMI range" and how is it calculated?
BMI is calculated as weight(kg) ÷ height(m)². The "healthy weight" category is commonly defined around BMI 18.5 to <25, with ≥25 considered overweight. We convert BMI 18.5 and 25 into a weight range for your height.
Can I use this if I'm taking Ozempic, Wegovy, Mounjaro, or Zepbound?
Yes. This tool doesn't depend on the medication you take—it only uses height (and optionally your current weight). If you're on GLP‑1 therapy, consider using these results as a starting point for a goal you confirm with your clinician.
Why do the formulas give different "ideal" weights? Which one is correct?
They were developed in different contexts and make different assumptions. None of them measures body composition (fat vs muscle), so it's normal to see a spread. The most useful takeaway is the range, not a single number.
What is Adjusted Body Weight and when is it shown?
Adjusted Body Weight (ABW) is shown when your current BMI is 30 or higher. It's used in clinical and nutrition contexts to avoid overestimating needs for people with obesity. The formula is: IBW (at BMI 25) + 0.25 × (current weight − IBW). This gives a reference weight between your IBW and actual weight.
Does this work for teens or children?
Not well. These IBW formulas were developed for adults. For people under 20, BMI interpretation uses age- and sex-specific percentiles rather than adult BMI cutoffs. Use CDC BMI-for-age growth charts instead.
Data Sources
This calculator uses evidence-based formulas from the following sources:
- Peterson et al., 2016 — Peer-reviewed summary table of common IBW equations (Devine, Robinson, Miller, Hamwi) and discussion of how IBW equations relate to BMI ranges
- CDC — Adult BMI Categories — Defines adult BMI categories including "Healthy Weight" (18.5 to <25) and "Overweight" (25 to <30)
- WHO — Obesity and Overweight — Provides widely used BMI threshold definitions (normal range 18.5–24.9; overweight ≥25)
- Manual of Dietetic Practice (BDA) — Source for Adjusted Body Weight formula used in clinical nutrition when BMI ≥ 30: IBW + 0.25 × (actual − IBW)
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All Tools⚠️ Important Medical Disclaimer
This calculator is for informational purposes only and does not constitute medical advice. Always consult with your healthcare provider before making any changes to your medication dosing.
Dosage calculations should be verified by a healthcare professional. Glapp and its contributors assume no liability for medication dosing errors or adverse events.
Off-Label Use Notice: Split dosing features represent off-label use not approved by the FDA. Discuss with your prescriber before implementing.