Fluid Balance Calculator
Calculate fluid balance to monitor patient fluid intake and output and assess hydration status.
Important Medical Disclaimer
This calculator is an educational and clinical decision support tool. Results DO NOT replace professional medical evaluation, laboratory tests, or clinical judgment. Always consult a qualified healthcare professional for diagnosis, treatment, and clinical decisions. Calculations are based on scientifically validated formulas but may not be applicable to all patients.
Calculate Balance
What is Fluid Balance?
Fluid balance is the systematic recording of all fluid intake (oral, intravenous, enteral) and output (urine, drains, vomiting, stool) over a defined period (usually 24h). The result (intake - output) indicates whether the patient is retaining fluids (positive balance), losing (negative balance), or balanced. It is fundamental in ICU, postoperative, kidney/heart failure, and critical cases.
When to use Fluid Balance?
Use in critical patients, postoperative major surgery, heart or kidney failure, shock, major burns, diuretic use, parenteral nutrition, and whenever strict fluid control is needed. Record every 6-8h and calculate 24h total. Consider insensible losses (skin, respiration ~500-800mL/day in adults).
Limitations and Considerations
Insensible losses (perspiration, respiration) are generally not accurately measured. Fever, tachypnea, and hot environment increase insensible losses. Patients with fistulas, multiple drains, or voluminous diarrhea require special attention. Weigh patient daily (gain/loss of 1kg ≈ 1L of fluid). Always correlate with physical examination, vital signs, and laboratory tests.
Frequently Asked Questions about Fluid Balance
Is positive balance always bad?
Not necessarily. Slightly positive balance may be expected in immediate postoperative or volume replacement. However, strongly positive balance (>1000mL/24h) may indicate fluid overload, especially in cardiac or renal patients. Always correlate with clinical picture.
How to calculate insensible losses?
In normothermic adults, estimate ~500-800mL/day (400mL skin + 400mL respiration). For each 1°C of fever, add ~200mL/day. Tachypnea, dry/hot environment, and major burns significantly increase losses. Use these estimates when direct measurement is not possible.
What is adequate urine output?
In adults, normal output is 0.5-1mL/kg/h (or ~30-50mL/h, minimum 1200-1500mL/24h). Output <0.5mL/kg/h for >2h indicates oliguria and requires investigation. Anuria (<100mL/24h) is an emergency. Polyuria (>3000mL/24h) may indicate diabetes insipidus, diuretics, or other causes.
Should I include solid food in the balance?
No, usually only liquids are counted. However, water-rich foods (soups, gelatin, fruits) should be estimated. Enteral/parenteral nutrition counts fully. The important thing is to standardize the method at the institution and maintain consistency in recording.