Urine Output Calculator

Calculate urine output in mL/kg/hr. Essential tool for assessing renal function and fluid balance in clinical settings.

Weight in kg
Weight in lb
kg
Enter patient weight in kilograms (0.1-300 kg)
Please enter a valid weight between 0.1 and 300 kg
0.1 kg 70 kg 300 kg
years
Age affects normal urine output ranges (0-120 years)
Please enter a valid age between 0 and 120 years
Select patient category for appropriate reference values
Urine Collection Data
mL
Total urine volume collected during the time period (1-5000 mL)
Please enter a valid volume between 1 and 5000 mL
Hours
Minutes
Days
hours
Time period over which urine was collected (0.1-168 hours)
Please enter a valid time between 0.1 and 168 hours
Optional Laboratory Values

Enter lab values for comprehensive renal assessment

mg/dL
Normal: 0.6-1.2 mg/dL
mg/dL
Normal: 7-20 mg/dL
mEq/L
Normal: 135-145 mEq/L
Click to load common clinical urine output scenarios
Add notes about medications, comorbidities, or other relevant factors

Medical Guidelines & Clinical Considerations

Important Clinical Note: Urine output monitoring is a screening tool, not a diagnostic test. Always correlate with clinical assessment, laboratory values, and patient history.

Clinical Decision Support

Assessment Protocol
  1. Verify accuracy of urine collection method
  2. Consider insensible losses (respiratory, skin)
  3. Review medications affecting urine output
  4. Assess for signs of dehydration/overload
  5. Correlate with creatinine and BUN trends
When to Consult Nephrology
  • Anuria persisting > 2 hours despite intervention
  • Oliguria with rising creatinine
  • Urine output abnormalities with electrolyte imbalances
  • Suspected acute kidney injury (AKI)
  • Complex fluid/electrolyte disorders

Understanding Urine Output

Urine output is a critical vital sign that provides important information about renal function, hydration status, and circulatory adequacy. Monitoring urine output is essential in hospitalized patients, especially in critical care, surgical, and pediatric settings.

Clinical Importance: Urine output is one of the most sensitive indicators of tissue perfusion and renal function. Changes in urine output often precede changes in serum creatinine and other markers of renal impairment, making it an early warning sign of acute kidney injury (AKI).

Normal Urine Output Ranges

Patient Category Normal Range Oliguria Threshold Anuria Threshold Clinical Considerations
Adults 0.5 - 1.0 mL/kg/hr < 0.5 mL/kg/hr < 0.3 mL/kg/hr Standard reference for most patients
Pediatrics 1.0 - 2.0 mL/kg/hr < 1.0 mL/kg/hr < 0.5 mL/kg/hr Children have higher metabolic rates
Neonates 1.0 - 3.0 mL/kg/hr < 1.0 mL/kg/hr < 0.5 mL/kg/hr Very high normal range in first week
Geriatrics 0.5 - 1.0 mL/kg/hr < 0.5 mL/kg/hr < 0.3 mL/kg/hr May have decreased renal reserve
Renal Disease 0.3 - 1.0 mL/kg/hr < 0.3 mL/kg/hr < 0.1 mL/kg/hr Lower thresholds for CKD patients
Cardiac Patients 0.5 - 1.0 mL/kg/hr < 0.5 mL/kg/hr < 0.3 mL/kg/hr Monitor closely with diuretic therapy

Frequently Asked Questions

The minimum acceptable urine output for an adult is typically 0.5 mL/kg/hr. However, this can vary based on clinical context. For example, in critically ill patients, many guidelines use 0.5 mL/kg/hr as the threshold for oliguria. It's important to note that sustained urine output below 0.3 mL/kg/hr is considered anuria and requires immediate medical attention.

Normal urine output varies significantly with age. Infants and children have higher metabolic rates and therefore higher normal urine output (1-2 mL/kg/hr for children, 1-3 mL/kg/hr for neonates). Adults typically have normal ranges of 0.5-1.0 mL/kg/hr. Elderly patients may have decreased renal reserve but similar normal ranges, though they are more vulnerable to dehydration and renal impairment.

For urine output calculation, use the patient's actual body weight in most clinical situations. The kidneys filter blood based on actual circulating volume, which correlates with actual body weight. However, in morbidly obese patients, some clinicians use adjusted body weight or lean body weight, though there's no universal consensus. Document which weight was used for calculation.