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FITTA tool

Healthy weight range and the four classic IBW formulas

Healthy BMI range plus Devine, Robinson, Miller, and Hamwi estimates

These calculators provide estimates based on population-level formulas and do not replace assessment by a dietitian, physician or exercise professional.

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Biological sex
Metabolic formulas use different constants by biological sex.

Turn a one-off range into a weekly trend in FITTA

FITTA logs body weight next to training, meals, and water so you can see whether the range and the plan are moving together.

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Practical guide

How to use FITTA better.

Ideal weight is not a single number. This calculator returns the mass that maps to BMI 18.5 to 24.9 at your height and, beside it, four classic point estimates: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). All four use stature and sex. None use age, body fat, or lean mass. The output is a screening estimate, not an aesthetic target, and it does not replace a clinician. FITTA keeps the same height and weight as a trend next to training, meals, and water.

What the healthy weight range is and how to calculate it

The healthy weight range on this page is the mass that, at the height you enter, produces a BMI between 18.5 and 24.9, the WHO adult cutoffs. It is not a single weight. Minimum weight equals 18.5 times height in meters squared. Maximum weight equals 24.9 times the same height squared. Convert centimeters first: 175 cm is 1.75 m. At 1.75 m the square is 3.0625, so the range is 18.5 × 3.0625 = 56.7 kg to 24.9 × 3.0625 = 76.3 kg, about 125 to 168 lb. At 1.65 m it runs from 50.4 to 67.8 kg. At 1.80 m, from 59.9 to 80.7 kg.

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Each BMI point equals height squared in kilograms: 3.06 kg at 1.75 m and 2.56 kg at 1.60 m. The calculator applies those coefficients and returns the range in kg. The cap is 24.9, the last value in the WHO normal band.

Devine, Robinson, Miller, and Hamwi: formulas and coefficients

The four classic formulas estimate a point, not a range. They were built for drug dosing and hospital charts, not for people who lift. The page converts height to inches over 152.4 cm (5 feet): (height in cm ÷ 2.54) − 60. Below 152.4 cm the extra term is zero and only the sex constant remains.

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Devine (1974): men 50 + 2.3 × inches; women 45.5 + 2.3 × inches. Robinson (1983): men 52 + 1.9 × inches; women 49 + 1.7 × inches. Miller (1983): men 56.2 + 1.41 × inches; women 53.1 + 1.36 × inches. Hamwi (1964): men 48 + 2.7 × inches; women 45.5 + 2.2 × inches. Hamwi’s original imperial form is 106 lb + 6 lb per inch over 5 feet for men and 100 lb + 5 lb per inch for women.

A man at 175 cm: 175 ÷ 2.54 = 68.90 in, or 8.90 in over 5 feet. Devine = 50 + 2.3 × 8.90 = 70.5 kg (155 lb). Robinson = 52 + 1.9 × 8.90 = 68.9 kg. Miller = 56.2 + 1.41 × 8.90 = 68.7 kg. Hamwi = 48 + 2.7 × 8.90 = 72.0 kg (159 lb). A woman at 165 cm, 4.96 in over 5 feet: Devine 56.9 kg, Robinson 57.4 kg, Miller 59.8 kg, Hamwi 56.4 kg. FITTA calculates with these coefficients.

How to read the range and the four point estimates

The BMI range describes population risk. The four formulas describe a historical point, usually near the middle of that range. At 175 cm in a man, Devine (70.5 kg) is BMI 23.0 and Hamwi (72.0 kg) is BMI 23.5, while the range runs from 56.7 to 76.3 kg. Four close numbers do not demand a decision. A weight far outside the range does call for body composition.

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None of the equations see muscle. A lifter at 175 cm and 82 kg sits above the range (BMI 26.8) and above Hamwi, and may still be lean. The reverse: 62 kg on the same man (BMI 20.2) is inside the range and below all four formulas, with little lean mass. Read the classic point as a historical dosing anchor and the 18.5–24.9 band as a screening zone. A four-week trend outweighs a single calculation.

Common mistakes when you calculate ideal weight

Leaving height in centimeters for the BMI range blows up the result: 18.5 × 175² is not a body weight. Convert 175 cm to 1.75 m first. On the classic formulas, skipping the divide by 2.54 is the matching error. Doing 175 − 60 = 115 and multiplying by the coefficient adds tens of kilograms. The correct term is 175 ÷ 2.54 − 60. Using the male constant on a woman shifts 4.5 kg on Devine alone (50 versus 45.5).

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Treating the Devine point as a required weight is the most common reading error. The equation was published for theophylline dosing, not for aesthetics or hypertrophy. Chasing the lowest of the four numbers with an aggressive deficit costs lean mass. Below 152.4 cm (5 feet) the classic formulas were not calibrated, and this page zeros the extra term. Rounding height up and weighing at random times move the result near the edges.

  • Use meters for the BMI range, never raw centimeters
  • Inches over 5 feet = height in cm ÷ 2.54 − 60
  • Apply the sex-specific constant in every formula
  • Devine is not an aesthetic or training target
  • Below 152.4 cm the classic formulas lose meaning

How to use the result in training and diet

If body weight sits above the range and composition confirms extra fat, use a 300 to 500 kcal deficit below daily expenditure, protein at 1.6 to 2.2 g per kg, and strength work two to four days a week. Losing 0.4 to 0.7 kg per week protects lean mass better than sharp cuts. At 1.75 m, moving from 82 kg (BMI 26.8) down to 76.3 kg is about 5.7 kg.

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If body weight sits below the range, prioritize a 250 to 400 kcal surplus, the same protein per kilogram, and progressive loading. Moving from 48.0 to 50.4 kg at 1.65 m is 2.4 kg. If you already sit inside the range and you train, you do not need to chase Devine or Hamwi. Use the classic point only when a clinician wants a single number. FITTA logs weight, training, meals, and water in one stream. This page is a screening estimate. Clinical calls belong to a physician or dietitian.

When the formulas disagree and what they miss

Hamwi rises faster with height: the male coefficient is 2.7 kg per inch, versus 1.41 in Miller. A man at 190 cm has 14.80 inches over 5 feet. Devine 84.0 kg, Robinson 80.1 kg, Miller 77.1 kg, Hamwi 88.0 kg (about 185, 177, 170, and 194 lb). The BMI range at the same 1.90 m runs from 66.8 to 89.9 kg. Miller sits near the center; Hamwi hugs the ceiling.

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All four ignore age, ethnicity, bone density, and training. They do not apply to children, adolescents, pregnancy, or edema. To tell whether extra mass is muscle, pair the number with waist circumference, a body-fat estimate, and loads. If weight rises, waist holds, and lifts go up, the gain is leaner. If weight and waist rise together, the gain is fat. Adjust calories and volume from a four-week trend, not from the average of the four formulas.

Frequently asked questions

What is a healthy weight for my height

There is no single ideal weight. The population reference is the BMI 18.5 to 24.9 range. At 1.70 m that is 53.5 to 72.0 kg. At 1.80 m, 59.9 to 80.7 kg. The classic formulas return a point inside that band: for a man at 1.75 m, Devine is 70.5 kg (155 lb) and Hamwi is 72.0 kg (159 lb). The weight where you train well may sit near an edge if composition is favorable.

How do you calculate ideal body weight

For the healthy range, multiply 18.5 and 24.9 by height in meters squared. At 1.75 m the square is 3.0625 and the range is 56.7 to 76.3 kg. For the classic formulas, compute inches over 5 feet: height in cm divided by 2.54, minus 60. Add the sex constant to the coefficient times that term. Devine for men is 50 + 2.3 × inches. This page runs all five calculations.

What is the Devine formula for ideal weight

Devine (1974) estimates weight in kg from height. Men: 50 + 2.3 kg per inch over 152.4 cm (5 feet). Women: 45.5 + 2.3 kg per inch over 5 feet. Inches over 5 feet = height in cm ÷ 2.54 − 60. At 175 cm in a man that is 8.90 inches and the result is 70.5 kg, about 155 lb. The equation was written for theophylline dosing, not as a training target.

What is the ideal weight for a 5 foot 9 man

There is no single value. Five-foot-nine is about 175 cm. The BMI 18.5–24.9 range at 1.75 m is 56.7 to 76.3 kg (125 to 168 lb). The classic formulas land in the middle: Devine 70.5 kg, Robinson 68.9 kg, Miller 68.7 kg, Hamwi 72.0 kg. A lifter can sit above 76 kg with low fat. Use the range as a zone and composition to judge extra mass.

Ideal weight or BMI which should I use

Use both. BMI returns a range for your height. The classic formulas return a point, usually near BMI 22 to 23.5. The range describes population risk. The point describes an old hospital convention. If you lift, read both next to waist, loads, and the weight trend, instead of picking one number and ignoring the rest.

Can I weigh more than ideal weight if I lift

Yes. Devine, Robinson, Miller, and Hamwi do not split muscle from fat. A man at 1.75 m and 82 kg sits above the range (BMI 26.8) and above Hamwi (72.0 kg) and can still be lean. The reverse is also true: landing on the Devine point with little lean mass and a large waist. If you train with heavy loads, read ideal weight next to circumferences and performance.

Is the Hamwi formula still used

Hamwi (1964) still appears in clinical charts. The metric coefficients on this page are 48 + 2.7 × inches over 5 feet for men and 45.5 + 2.2 × inches for women, matching 106 lb + 6 lb per inch and 100 lb + 5 lb per inch. Because the slope is steeper, Hamwi rises faster with height than Miller. At 175 cm in a man it is 72.0 kg. Treat it as a historical anchor, not a hypertrophy target.

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These calculators provide estimates based on population-level formulas and do not replace assessment by a dietitian, physician or exercise professional.