# Geriatric BMI Calculator (Over 65)

URL: https://speedycalculator.com/calculators/health/geriatric-bmi/
Last updated: 2026-10-30

> The geriatric BMI calculator works out body mass index for adults over 65 and rates it with the cut-offs used in geriatric care, where a BMI below 23 is considered underweight because it is linked with higher mortality in older people.

## Inputs

- Age (years)
- Weight (kg, lb, st, g)
- Height (cm, in, m, ft, mm)

## Results

- BMI
- Weight at BMI 23
- Weight at BMI 29.9

## Formula

```
BMI = weight ÷ height²
Older adults: < 23 underweight · 23–29.9 healthy · ≥ 30 overweight or obese
```

## Explanation

In older adults a slightly higher BMI appears protective: studies show the lowest mortality around BMI 24–31 after age 65, and weight loss is often a warning sign of illness or malnutrition. Muscle loss (sarcopenia) also means BMI can hide low muscle mass.

### How to use the Geriatric BMI Calculator

- **Age**
- **Weight**
- **Height**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter age, weight and height. If height is hard to measure because of curvature of the spine, use the bedridden height estimation calculator first. The result is compared with the cut-offs used by the Nutrition Screening Initiative and in geriatric practice.

### Inputs explained

FieldWhat to enterAgeIn yearsWeightUnits: kg, lb, st, gHeightUnits: cm, in, m, ft, mm

### What each result means

- **BMI** = [Weight]÷([Height]÷100)^2
- **Weight at BMI 23** = 23×([Height]÷100)^2
- **Weight at BMI 29.9** = 29.9×([Height]÷100)^2

*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Age: 75 years; Weight: 68 kg; Height: 165 cm.

Results — **BMI = 25**; Weight at BMI 23 = 62.6 kg; Weight at BMI 29.9 = 81.4 kg.

## Key terms

- **Sarcopenia**: Age-related loss of muscle mass and strength.

## FAQ

**Why is the healthy range different after 65?**
Higher BMI is linked with better survival in older adults, possibly because reserves help during illness.

**Is unintentional weight loss a concern?**
Yes – losing more than 5% in 6–12 months should be discussed with a doctor.

**What else should be checked?**
Muscle strength, appetite and a nutrition screen such as MUST or MNA.


## Sources

- [Winter JE et al. BMI and all-cause mortality in older adults: a meta-analysis. Am J Clin Nutr, 2014](https://pubmed.ncbi.nlm.nih.gov/24452240/)
- [Nutrition Screening Initiative – Determine your nutritional health](https://www.ncbi.nlm.nih.gov/)