Fluid Deficit Calculator

The goal is to safely lower serum sodium. Correcting too quickly can cause cerebral edema, so the standard target is a 10 to 12 mEq/L drop per 24 hours.

Total Body Water (TBW) is the estimated percentage of body weight that is water: adult male 0.6, adult female 0.5, elderly male 0.5, elderly female 0.45. For a 70 kg adult male, TBW is 42 liters.

Deficits are usually replaced over 48 to 72 hours using D5W (free water equivalent), half-normal saline (0.45% NaCl), or oral water, following institutional protocols with frequent sodium rechecks.

Common causes include dehydration (inadequate water intake), diabetes insipidus, excessive sodium intake, and conditions causing excessive water loss such as fever, burns, or osmotic diuresis.

Rapid lowering of sodium can cause water to shift into brain cells, leading to cerebral edema. This is why correction is limited to 10 to 12 mEq/L per 24 hours.

No. This tool is for educational purposes only. Fluid and electrolyte management should always be supervised by a qualified healthcare professional.

You can. Look for the "Embed" button near the top of this calculator. It lets you pick a size, border style, and color palette, then gives you an iframe tag to paste into any webpage. The widget is responsive, loads fast, and costs nothing. More details at calculory.com/services/embed-calculators.