Mild dehydration is equivalent to 2-3% of body weight; moderate dehydration is equivalent to 4-6% of body weight, i.e., 2400ml~3600ml; severe dehydration is equivalent to 7-14% of body weight, and more severe cases can reach over 15%.

Fluid Volume (ml) = [Original Weight (kg) - Current Weight (kg)] × (30~40ml/kg)

Male: Fluid Volume (ml) = [(Actual Hematocrit - 0.48)/0.48] × Weight (kg) × 200

Female: Fluid Volume (ml) = [(Actual Hematocrit - 0.42)/0.42] × Weight (kg) × 200

Male: Fluid Volume (ml) = 4 × Current Weight (kg) × [Measured Serum Sodium (mmol/L) - 142]

Female: Fluid Volume (ml) = 3 × Current Weight (kg) × [Measured Serum Sodium (mmol/L) - 142]

Clinically, it should be noted that relying solely on any formula to determine sodium supplementation is not advisable. The formula is only an estimate of the safe dose of sodium supplementation. During fluid therapy, be cautious of excessive blood volume, which can be very dangerous for those with heart failure.