Free Water Deficit (Body weight, Na)
Free Water Deficit: calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.
ℹ Reference calculation based on the published method. It does not replace a clinical examination or a doctor's decision.
Free Water Deficit
Body weightkg
Nammol/L
Male sex (1 = yes)
Age ≥65 years (1 = yes)
Free water deficit
3L
Total body water
42.0L
More about: Free Water Deficit (Body weight, Na)
What it calculates
The “Free Water Deficit (Body weight, Na)” calculator computes Free water deficit in L from 4 parameters: body weight (kg), na (mmol/L), male sex (1 = yes), age ≥65 years (1 = yes).
Used by professionals and patients to assess health metrics, dosages, and risks.
Example calculation
With parameters Body weight = 70 kg, Na = 150 mmol/L, Male sex (1 = yes) = 1, Age ≥65 years (1 = yes) = 0 the result is 3 L (Lower Na by no more than 10 mmol/L per 24 h).
How to use
- Enter body weight, na, male sex (1 = yes) and age ≥65 years (1 = yes) — each field above is adjustable with a slider.
- Free water deficit (L) is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is BMI calculated?
BMI = weight (kg) / height (m)². Example: 70 kg / (1.75 m)² = 22.9. The WHO normal range is 18.5–24.9; below that is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes may show a high BMI with low body fat. It is also less reliable for teenagers, pregnant people, older adults, and very tall or short individuals.
What are the BMI categories?
Underweight: below 18.5. Normal: 18.5–24.9. Overweight: 25–29.9. Obese class I: 30–34.9; class II: 35–39.9; class III: 40+.
What is a better measure than BMI?
Body fat percentage, waist-to-height ratio (aim for under 0.5), and waist circumference give a clearer picture of health than BMI alone.
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