Urine Output Calculator


Urine Output And Its Importance

Urine tests are used in a wide range of diagnoses – whether it is to confirm pregnancy or determine if the person has UTI or STI. Adequate hydration is essential for the proper functioning of the human body. Urine output and fluid balance can directly indicate kidney and bladder performance. Urine output is also monitored in cases of critical diseases like bladder cancer or drug (ab)use. It is also an important part of pre-employment screening

Regular And Healthy Urine Output Rate

The normal urine output per hour helps to determine if an individual is producing the right amount of urine in a cycle of 24 hours. The range of normal urine output per day is 800 to 2,000 mL. In other words, 0.5 to 1.5 cc/kg/hour is considered as the normal urine output per hour.

The normal urine output per kg and normal urine output per hour need to be measured as the amounts of chemicals, like protein, uric acid, ammonia, sodium, potassium, nitrogen, urea, creatine, and hormones are directly proportional to the amount of urine output. As per research, the normal urine output for adults and children differs. The chart below provides an overview:

Adult>0.5 mL/kg/hr
Child>1 mL/kg/hr
Neonate>2 mL/kg/hr

How To Use The Urine Output Calculator

While calculating the urine output rate in mL/kg/hr and fluid balance, the considered variables are as follows: fluid intake, patient weight, and the total urine output in a specific period. Generally, a cycle of 24 hours is taken for calculation.

The urine output calculator uses the following equations:

Urine output in mL/kg/hr = Total urine output in mL / (Weight in kg x Hours)

Fluid balance in mL = Fluid intake in mL – Total urine output in mL.

In healthy adults, normal values for total urine output are 800 – 2000 mL (considering a fluid intake of 2 L and a period of 24 hrs).

Frequency Of Urination In A Day

The normal urine output for adults varies. Usually, most individuals urinate 6 or 7 times in a 24-hour cycle or a day. Urination between 4 to 10 times in a day is generally considered healthy. The frequency of urination depends on the quality of life and lifestyle and liquid intake. A few factors that influence this are:

  • Fluid intake
  • Age
  • Medical conditions (such as diabetes and UTI)
  • Size of the bladder
  • Types of fluids consumed (consumption of alcohol and caffeine can increase urine production)
  • Supplements or diabetes medications

A normal person who consumes 64 ounces of fluid in a 24-hour cycle may urinate about 7 times.

Excessive Urination Volume And Causes

Excessive urination syndrome or polyuria is a condition in which a patient urinates more than the normal range. The urine volume is considered to be excessive if it is more than two and a half liters a day.

Excreting excessive volumes of urine is a common condition, and you may experience it for several days. However, it should not be a continuous practice. If the individual produces abnormal amounts of urine during sleep, it is abnormal and is called nocturnal polyuria or nocturia.

The causes of polyuria are:

  • A CT scan or any other hospital test in which a dye is injected into the patient’s body.
  • Drinking large amounts of liquids.
  • Drinking alcohol and caffeine.
  • High blood pressure, kidney disorder, or diabetes mellitus.

Overview Of Lesser Urine Output

The medical term for decreased urine output is oliguria. An individual has oliguria if the urinary output is lesser than 400 mL (13.5 ounces) in a cycle of 24 hours. The absence of urine is called anuria, and in this condition, a person urinates lesser than 50 mL a day.

Oliguria can be temporary or seriously permanent. A few causes of oliguria are:

  • Dehydration
  • Infection Or Trauma: These are serious causes as these can lead to shock. Shock eliminates blood flow to different organs. Shock is an emergency medical condition that requires immediate attention.
  • Urinary Tract Obstruction: If there is any obstruction or blockage in the urinary tract. This occurs when urine fails to leave the kidneys.

Kidney Failure And Decreased Urine Output

Decreased urine output is a symptom of kidney failure, but it is not the sole cause.

The kidneys are a pair of organs located in the lower back. These organs filter food and eliminate toxins from the body through urine. In the interim transfer phase, the toxins remain within the bladder. If kidneys lose the ability to filter waste from the blood, it can lead to kidney failure.

Factors that may interfere with your kidney health are:

  • Severe dehydration
  • Prolonged medication
  • Toxic exposure to environmental pollutants
  • Kidney trauma

If the body becomes overloaded with toxins, the kidneys fail to perform their normal activities. This can lead to kidney failure. Hence, it is recommended to check the urine output rate with the help of the urine output calculator to ensure you maintain the normal output rate.

Key facts about urine output

In order to calculate the urine output rate in mL/kg/hr and fluid balance, the following variables are considered: patient weight, fluid intake and the total urine output per period of time, usually a 24h period is considered. 

The urine output calculator uses the following equations:

■ Urine output in mL/kg/hr = Total urine output in mL / (Weight in kg x Hours);

■ Fluid balance in mL = Fluid intake in mL - Total urine output in mL.

Urine output can offer information on whether the kidneys function normally, in terms of blood filtration and excretion of waste products through urine.

Total urine output for an adult, during 24h is of 800 to 2000 mL, this is equivalent to around 1 mL/kg/hr. In an adult weighing 60 kg, this means 60 mL/hr.

Urinary output (the 24-hour urine collection test) is one of the most common laboratory tests, which checks for creatinine, sodium, potassium, protein presence and nitrogen levels.

Urinary output is however, impacted by other factors such as:

■ Existence of chronic kidney disease;

■ Dehydration;

■ Certain drugs;

■ Caffeine and alcohol intake;


Fluid balance

FB consists in the difference between declared fluid intake and total urine output (water lost should be equal to water in).

Its mechanism of control is osmoregulation, electrolyte concentration and hormonal regulation through anti diuretic hormones. Some also include here behaviour in order to maintain euvolemia.

When referring to input fluid, we refer to drinking, eating and parenteral intake. Output fluids are those of respiration, perspiration, expectoration, urine and defecation.



The main causes of oliguria include:

■ renal causes;

■ septic shock;

■ drug toxicity;

■ myoglobulin release.

Oliguria, or hypo-perfusion, starts at:

■ In adults: urine output

■ In children:

Acute oliguria is less than 400 mL of urine output per day. The mechanism involves a sudden drop in glomerular filtration rate which in turn determines an increase in plasma urea and urine creatinine concentration. Development of acidosis and hyperkalemia follow, along with retention of salt and water.

Early identification of oliguria and decreases in GFR means that further kidney damage can be prevented.

According to RIFLE (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease) classification definition of the Acute Dialysis Quality Initiative, the conditions for acute kidney injury (AKI) are:

■ Less than 0.5 mL/kg/hr for more than 6h at a time (high risk AKI);

■ Less than 0.5 mL/kg/hr for more than 12h at a time (positive AKI diagnosis);

■ Less than 0.3 mL/kg/hr for more than 24h at a time or anuria for 12h (acute renal failure).

Polyuria on the other hand, is defined as abnormal volumes of urine, larger than normal, usually (if not triggered by high fluid intake) a symptom of diabetes insipidus, some forms of kidney disease or prolonged use of diuretic medication.