Ideal Weight Calculator
Calculate ideal body weight using Devine, Robinson & Miller formulas
The Ideal Weight Calculator estimates a healthy body weight range based on your height and gender. It uses four clinically validated formulas (Devine, Robinson, Miller, and Hamwi) to provide a consensus result.
Inputs Explained
- Sex: Determines the baseline muscle/fat ratio assumptions in the formulas.
- Height: The primary factor for all ideal weight calculations.
Formulas Used
We calculate results using the Devine (Standard), Robinson, Miller, and Hamwi equations, then provide an average range to account for individual variations.
Formula
Devine (Men): 50 + 2.3kg per inch over
5ft
Devine (Women): 45.5 + 2.3kg per inch over 5ft
Formula Comparison
| Formula | Notes |
|---|---|
| Devine | Most common, medical use |
| Robinson | Slightly lower estimates |
| Miller | Higher estimates |
| Hamwi | Oldest formula |
Related
Complete Guide to Ideal Body Weight (IBW)
Ideal Body Weight (IBW) was originally derived to determine drug dosages for patients. Today, it serves as a useful benchmark for setting long-term weight goals, though it shouldn't be treated as an absolute limit.
Step-by-Step Example
Let's calculate the IBW for a sample profile:
- Profile: Male, 178 cm (approx. 5ft 10in).
- Variable: "Inches over 5 feet" = 10 inches.
Calculation (Devine Formula):
- Base Weight (Male): 50 kg.
- Additional Weight: 2.3 kg per inch over 5ft.
- Math: 50 + (2.3 × 10) = 50 + 23 = 73 kg.
Result: The Devine ideal weight is 73 kg. Other formulas may give slightly different results (e.g., Robinson might be 71 kg), giving you a healthy "range" to aim for.
The Formulas Explained
- Devine (1974): The standard medical formula. Used for dosing narrow therapeutic index drugs.
- Robinson (1983): Adjusted Devine's data to be more accurate for modern populations.
- Miller (1983): Often yields lower values; better suited for estimating "lean" mass.
- Hamwi (1964): The "Rule of Thumb" formula. Easy to memorize (106 lbs + 6 lbs/inch for men).
Use Cases
- Medical Dosing: Doctors use IBW to prescribe correct amounts of anesthesia.
- Goal Setting: Provides a specific target number rather than a broad BMI range.
- Nutritional Planning: Dietitians often estimate calorie needs (BMR) based on Ideal Weight for obese patients to avoid overfeeding.
Assumptions & Limitations
- Muscle Mass Ignored: A bodybuilder at 5'10" might weigh 90kg (Obese by IBW standards) but have very low body fat.
- Bone Structure: The formulas assume a "medium" body frame. Small frames should subtract 10%; large frames add 10%.
- Age Factor: It is often healthier for older adults (65+) to be slightly above their calculated IBW to provide a buffer against illness.
Sources & References
- Devine, B. J. (1974): Gentamicin therapy. Drug Intelligence & Clinical Pharmacy. (Origin of the Devine formula).
- Pai, M. P., & Paloucek, F. P. (2000): The origin of the "ideal" body weight equations. Annals of Pharmacotherapy.
- Hamwi, G. J. (1964): Therapy: changing dietary concepts. Diabetes.
Frequently Asked Questions
The **Devine Formula (1974)** is the most widely used in the medical field, particularly for dosing medications. However, the **Robinson** and **Miller** formulas were developed later to improve accuracy for different body types.
Each researcher used different population data set derivation methods. For example, Miller (1983) often calculates a lower ideal weight for taller men compared to Devine.
No. 'Ideal Weight' is a single number based on historical statistical averages. 'Healthy Weight' is a range (usually based on BMI) that provides flexibility for different body compositions.
No. These formulas do not account for muscle mass. A bodybuilder will almost always weigh more than their 'ideal weight' because muscle is distinctively heavy, but they may still be very healthy.
These specific formulas do not include age as a variable. However, logically and medically, it is accepted that maintaining a slightly higher weight can be beneficial as you age.