Adjusted Body Weight Calculator: 25% and 40%, Math Shown
Your adjusted weight with each ideal-weight formula side by side, the sum written out in your own numbers, and the sources for the 25% and 40% shares. Free.
Adjusted body weight is your ideal weight plus 25% of the weight above it. Hospital dietitians and pharmacists use it for feeding plans and medicine doses at higher weights. Enter five details to see yours, with the sum written out.
What is adjusted body weight?
Adjusted body weight is your ideal weight plus a share of the weight above it. It was proposed in 1984 for working out calorie and protein needs at higher weights, on the assumption that body fat uses almost no energy. The Academy of Nutrition and Dietetics says the research to support that assumption is lacking.
The share is 25% in nutrition and 40% for dosing some medicines. Many calculators use one without saying which, so this page shows both, with each of the four ideal-weight formulas.
How to calculate adjusted body weight
Here is the sum for a woman who is 5 ft 5 in (165.1 cm) tall and weighs 220 lb (99.8 kg).
- Find your ideal weight. This page uses the Hamwi formula: for women, 45.5 kg plus 2.2 kg for every inch over 5 ft; for men, 48 kg plus 2.7 kg. In the example: 45.5 + 2.2 × 5 = 56.5 kg.
- Subtract it from what you weigh. 99.8 − 56.5 = 43.3 kg above the ideal weight.
- Add 25% of that to the ideal weight. 43.3 × 0.25 = 10.8, and 56.5 + 10.8 = 67.3 kg (148 lb).
25% or 40%?
A calculator that gives you a different number is using the other share, or a different ideal-weight formula. The table in your results lists all eight combinations.
| Used for | Share of the weight above ideal |
|---|---|
| Calorie and protein needs | 25% |
| Doses of some medicines | 40% |
Karkeck first published the 25% share in 1984. Bauer and colleagues published the 40% share in 1983. Both references are under Formula and sources.
What it is for
Calories. For overweight and obese adults, the Academy of Nutrition and Dietetics' 2014 guideline says to estimate resting energy with the Mifflin-St Jeor equation and actual weight. The BMR calculator and the calorie deficit calculator both work that way.
Hospital care. Dietitians use adjusted or ideal body weight for some critically ill patients with a high BMI, when feeding is planned low in calories and high in protein.
A goal weight. Adjusted body weight is nearer than the ideal-weight formulas, and some dietitians use it as a step on the way. The first goal U.S. obesity guidelines set is nearer still: 5 to 10% of what you weigh today, which the ideal weight calculator works out.
Medicine doses. Which weight a dose is based on depends on the medicine. That decision belongs to the prescriber or pharmacist.
Formula & sources
Adjusted body weight
W = current weight and IBW = ideal body weight, both in kg to one decimal. f = 0.25 in nutrition and 0.4 for dosing some medicines. At or under the ideal weight nothing is adjusted and AdjBW = W.
Hamwi ideal weight (the basis of the headline)
IBW in kg; x = inches of height above 5 ft (60 in), and 0 for anyone shorter. The results table repeats the sum with the Devine, Robinson and Miller formulas from the ideal weight calculator.
Sources
- Karkeck J (1984) Adjusted body weight for obesity. American Dietetic Association Renal Dietitians Practice Group Newsletter 3:6. The origin of the 25% factor.
- Krenitsky J (2005) Adjusted body weight, pro: evidence to support the use of adjusted body weight in calculating calorie requirements. Nutr Clin Pract 20(4):468–473.
- Bauer LA, Edwards WA, Dellinger EP, Simonowitz DA (1983) Influence of weight on aminoglycoside pharmacokinetics in normal weight and morbidly obese patients. Eur J Clin Pharmacol 24(5):643–647. The dosing weight: ideal body weight plus 40% of the excess.
- Hamwi GJ (1964) Therapy: changing dietary concepts. In: Diabetes Mellitus: Diagnosis and Treatment. American Diabetes Association.
- Academy of Nutrition and Dietetics (2014) Adult Weight Management Evidence-Based Nutrition Practice Guideline, Assess Energy Needs: estimate resting metabolic rate in overweight or obese adults with the Mifflin-St Jeor equation using actual weight.
- Academy of Nutrition and Dietetics, Practice Trends Adjusted or Ideal Body Weight for Nutrition Assessment? Actual body weight for most assessments; adjusted or ideal body weight for some critically ill patients with an elevated BMI and for some medicine doses. The assumption behind the adjustment, that adipose tissue is inert, lacks evidence.
Adjusted body weight questions, answered
What is adjusted body weight?
Your ideal weight plus 25% of the weight above it. For a woman who is 5 ft 5 in and 220 lb, that is 148 lb (67.3 kg), against an ideal weight of 125 lb (56.5 kg).
What is the formula for adjusted body weight?
Adjusted body weight = ideal weight + 0.25 × (actual weight − ideal weight). For dosing some medicines, pharmacists use 0.4 in place of 0.25.
Should I use 0.25 or 0.4?
0.25 for nutrition: calorie and protein estimates. 0.4 for dosing medicines such as aminoglycoside antibiotics, where a pharmacist or prescriber makes the call. The results table shows both.
Is adjusted body weight the same as ideal body weight?
No. Ideal body weight comes from height alone. Adjusted body weight starts there and adds part of the weight above it, so it always sits between your ideal weight and what you weigh today.
Is adjusted body weight a good goal weight?
It is a nearer goal than ideal weight, and some dietitians use it that way. U.S. obesity guidelines set a smaller first goal: 5 to 10% of what you weigh today, over about six months. The ideal weight calculator shows yours.
Should I use adjusted body weight to work out my calories?
The Academy of Nutrition and Dietetics' 2014 guideline for overweight and obese adults says to use the Mifflin-St Jeor equation with actual weight. The BMR calculator does that, and the calorie deficit calculator turns it into a daily target.
What if I weigh less than my ideal weight?
Then there is nothing to adjust. Use your actual weight.