Calculate What Weight You Should Be
A professional Ideal Body Weight (IBW) calculator using medical formulas and frame size analysis.
Male
Female
Biological sex affects bone mass and muscle density assumptions.
Feet
Inches
Please enter a valid height (between 3′ and 8′).
Small Frame (-10%)
Medium Frame
Large Frame (+10%)
Estimated based on wrist circumference relative to height.
Your Ideal Weight Range
148 – 163
pounds (lbs)
Based on the Modified Devine Formula & Healthy BMI
Detailed Formula Breakdown
Hamwi Formula (1964):
160 lbs
Devine Formula (1974):
161 lbs
Healthy BMI Range (18.5-25):
125 – 169 lbs
Comparison Table
Comparison of different medical standards for the entered height.
| Method | Calculated Weight (lbs) | Calculated Weight (kg) |
|---|
Weight Spectrum Visualizer
Visualizing your ideal weight against BMI categories.
■ Underweight
■ Healthy
■ Overweight
■ Obese
What is the Calculation for What Weight You Should Be?
When you ask the question "calculate what weight you should be," you are typically looking for your Ideal Body Weight (IBW). This is a medically derived weight range that correlates with the lowest mortality rates and optimal health outcomes for a person of your specific height, gender, and skeletal frame size.
Unlike a simple scale reading, the process to calculate what weight you should be involves mathematical formulas developed by pharmacologists and actuaries. These formulas were originally created to calculate drug dosages (where metabolism matters) and insurance premiums (where longevity matters).
Who should use this calculation? Adults over the age of 18 who are looking to establish long-term health goals. It is particularly useful for setting target weights during weight loss programs or for athletes determining their optimal competition weight classes.
Common Misconceptions: The number derived when you calculate what weight you should be is not a singular "magic number." It is a baseline. Muscle mass, age, and pregnancy can significantly alter what is considered healthy for an individual.
Formulas and Mathematical Explanation
To accurately calculate what weight you should be, several established formulas are used. The most widely accepted in the medical community is the Devine Formula, though the Hamwi Formula is also popular for its simplicity.
1. The Hamwi Formula (1964)
This is often used for quick estimations in clinical settings.
- Men: 106 lbs for the first 5 feet + 6 lbs for every inch over 5 feet.
- Women: 100 lbs for the first 5 feet + 5 lbs for every inch over 5 feet.
2. The Devine Formula (1974)
Often considered the standard for calculating ideal body weight.
- Men: 50.0 kg + 2.3 kg per inch over 5 feet.
- Women: 45.5 kg + 2.3 kg per inch over 5 feet.
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Height (H) | Vertical stature | Inches/cm | 58″ – 80″ |
| Base Weight | Starting constant | lbs/kg | 100-106 lbs |
| Increment | Weight per inch | lbs/kg | 5-6 lbs |
Practical Examples
Example 1: The Average Male
Consider a male who is 5 feet 10 inches tall with a medium frame. He wants to calculate what weight he should be.
- Height over 5ft: 10 inches.
- Hamwi Calculation: 106 + (6 × 10) = 166 lbs.
- Result: His target ideal weight is approximately 166 lbs.
Example 2: The Petite Female
Consider a female who is 5 feet 2 inches tall with a small frame (requires a 10% reduction).
- Height over 5ft: 2 inches.
- Hamwi Base: 100 + (5 × 2) = 110 lbs.
- Small Frame Adjustment: 110 lbs – 10% = 99 lbs.
- Result: Her ideal weight target is roughly 99 lbs.
How to Use This Calculator
- Select Gender: Choose Male or Female. This adjusts the base constant of the formula (men generally have higher bone density).
- Enter Height: Input your height in feet and inches accurately. Even one inch can change the ideal weight by 5-6 pounds.
- Select Frame Size:
- Small: If your thumb and middle finger overlap when wrapping your wrist.
- Medium: If they just touch.
- Large: If they do not touch.
- Analyze Results: Look at the "Ideal Weight Range." This combines different formulas to give you a realistic window rather than a single impossible number.
Key Factors That Affect Results
When you calculate what weight you should be, consider these six critical factors that formulas might not fully capture:
- Muscle Mass vs. Fat: Muscle is denser than fat. An athlete may weigh significantly more than their "ideal" formula weight but be perfectly healthy with low body fat.
- Age: As we age, metabolism slows and muscle mass naturally decreases. Some studies suggest slightly higher weights in older age are protective against frailty.
- Bone Density: Genetic variances in skeletal density can account for 5-10 lbs of weight difference between two people of the same size.
- Hydration Levels: Daily weight can fluctuate by 2-4 lbs purely based on water retention, salt intake, and hydration status.
- Body Distribution: Visceral fat (around organs) is riskier than subcutaneous fat (under skin). Two people may have the same weight but different health risks based on where the weight is stored.
- Pregnancy and Post-Partum: Standard formulas do not apply to pregnant or breastfeeding women, as the body requires additional mass for fetal support and lactation.
Frequently Asked Questions (FAQ)
Does this calculator apply to children?
No. Children and teenagers are still growing, and their weight metrics are tracked using CDC growth charts, not adult IBW formulas. To calculate what weight you should be as a child, consult a pediatrician.
Why is the range so wide?
The "Healthy BMI" range is wide (e.g., 125-169 lbs) to accommodate different body types. The specific formulas (Hamwi/Devine) give a narrower "Ideal" target within that healthy range.
Is the Hamwi or Devine formula better?
The Devine formula is the most widely used in pharmacology for dosing. However, the Hamwi formula is often preferred by dietitians for setting weight goals because it is easier to explain and memorize.
What if I am very tall or very short?
Formulas are most accurate for heights between 5'0″ and 6'4″. Extreme heights may see skewed results; BMI ranges tend to be more reliable indicators for very tall or short individuals.
Does frame size really matter?
Yes. A large-framed individual trying to reach a weight calculated for a small-framed person may result in unhealthy muscle loss. Adjusting by 10% for frame size is a standard medical practice.
Can I calculate what weight I should be if I am a bodybuilder?
Standard IBW formulas and BMI are poor indicators for bodybuilders. You should rely on Body Fat Percentage measurements rather than simple weight calculations.
How often should I weigh myself?
For weight maintenance, once a week is sufficient. Daily fluctuations can be misleading and demotivating. Consistency (same time of day) is key.
Is being under the ideal weight healthy?
Not necessarily. Being significantly underweight carries risks such as weakened immune function, osteoporosis, and fertility issues. Aim for the "Healthy Range" provided.
Related Tools and Internal Resources
Expand your health tracking with our other specialized calculators:
- BMI Calculator – Determine your Body Mass Index category.
- Body Fat Percentage Tool – Estimate your lean mass versus fat mass.
- Calorie Deficit Calculator – Plan your weight loss nutrition strategy.
- Basal Metabolic Rate (BMR) – Find out how many calories you burn at rest.
- Macro Nutrient Calculator – Optimize your protein, carb, and fat intake.
- TDEE Calculator – Total Daily Energy Expenditure estimation.