How to measure fluid intake & output

Updated April 15, 2017

Measuring fluid intake and output gives an indication of how well the kidneys are functioning. Fluid is not necessarily what is taken by mouth but also includes intravenous fluids. Output measurement includes urine as well as captured drainage of other fluids such as blood and emesis. Patients with kidney disease, congestive heart failure or post-surgical are candidates for maintaining an intake and output record. Fluid overload is a dangerous condition as well as dehydration, and can require input and output measurements. Regardless of the reason, all measurements are monitored every one to two hours, and totalled at the end of a nursing shift.

Begin the fluid intake and output by recording all fluids in intravenous bags, Foley catheter bags and drainage bags. If the patient eats or drinks by mouth, record the amount of fluids by ounce and food by size. Record the amount of fluid intake every hour on the recording sheet. Mark the container of fluid with the time of recording for future measurements. Mark the intravenous fluids with the time of recording.

Place a urinal hat on the commode and instruct the patient to void in the hat and not directly into the commode. Instruct him not to remove the hat. Tell the patient to contact you when the hat needs emptying. Empty all fluids from the hat into a measuring cup and record the measurement.

Empty all Foley catheter and drainage bags and record the output measurement on the recording sheet. Measure the amount of vomit (emesis) and record it on the sheet. For bowel movements, record the number of times a bowel movement took place within the specific time period. If you are recording events for a baby that wears diapers, weigh the diaper after each use and record the weight.

Question the patient at every interval of recordings concerning fluid input not known to the staff. Instruct the patient to save all containers that held fluids. This includes Popsicles, jello, candy and pudding. Some input and output charts give conversions to ounces for these types of meals. If not, report the size of the meal.

Total the input and output measurements every eight hours. Report the intake and output on the patient's chart. Contact the physician if a serious difference in the intake and output occurs. The measurements should equal one another, minus a few ounces. An input that is much higher than the output is signs of fluid retention and can cause fluid overload. An output that is much higher than the input can result from dehydration.

Things You'll Need

  • Intake and output chart
  • Two measuring cups
  • Emesis basin
  • Urinal hat
  • Disposable gloves
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About the Author

Vickie Van Antwerp began her career as a technical writer for a consulting firm in 1987. Now a freelance writer in her fields of interest, her writings appear on, and in "The Phelps Connection" and "The Storyteller." Van Antwerp holds an Associate of Arts in liberal arts from Gloucester County College and certification as a surgical technologist from Lenoir College.