Medical Calculator – SonDoctor.com
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Free water clearance (FWC) Calculator

FWC = UV x (1-(U osm / P osm))
UV : Urine flow rate (L/day)
* If the 24-hour urine volume is not entered, only a POSITIVE or NEGATIVE result will be provided.







FWC POSITIVE: Indicates net excretion of free water, typically seen in states of water excess or when hypotonic urine is excreted. It reflects the body’s effort to eliminate excess water.
FWC NEGATIVE: Indicates net retention of free water, typically seen in states of dehydration or under the influence of antidiuretic hormone (ADH), where the kidneys actively conserve water by producing hypertonic urine.