Fluid Balance Calculator
Adding Up Every Route In and Out
Fluid balance tracking treats the body like a ledger: everything taken in by mouth, IV line, or other route on one side, everything lost through urine, stool, or other output on the other. The running difference between the two — positive, negative, or balanced — is one of the most basic and most closely watched numbers in inpatient nursing care.
The Formula
Total Intake = Oral Intake + IV Intake + Other Intake
Total Output = Urine Output + Stool Output + Other Output
Fluid Balance = Total Intake − Total Output
Total Output = Urine Output + Stool Output + Other Output
Fluid Balance = Total Intake − Total Output
A positive result indicates net fluid retention; a negative result indicates a net fluid deficit; zero indicates the intake and output are balanced.
Why This Number Is Tracked Closely
- Post-surgical monitoring — fluid shifts after surgery are common, and tracking balance helps catch retention or dehydration early.
- Heart failure and kidney disease management — patients with these conditions often have strict intake/output monitoring since fluid overload is a serious risk.
- ICU and critical care — fluid balance is charted on a regular schedule (often every shift) as part of routine vital tracking.
Note: This calculator totals the numbers you enter; it doesn't measure fluid loss through sweat, respiration, or other insensible routes, which clinicians estimate separately when a complete picture is needed.
How to Use This Calculator
- Enter oral intake in mL.
- Enter IV intake in mL.
- Enter any other intake in mL.
- Enter urine output in mL.
- Enter stool output in mL.
- Enter any other output in mL.
- Select Calculate to see the net fluid balance and its status.
Related Calculations
For infusion-side calculations feeding into the intake total, see the IV Infusion Calculator or the Drip Rate Calculator.