Intake and Output for CNAs: Measurement Guide and Exam Tips

Intake and output, almost always referred to as I&O, is the practice of tracking every fluid that enters and leaves a patient's body over a period of time, typically in 8-hour nursing shifts. Fluid intake includes everything a patient drinks or receives through a feeding tube. Fluid output includes urine, but can also include vomit, wound drainage, or diarrhea when these are ordered to be measured. Monitoring I&O helps the care team detect fluid imbalances early, before they become dangerous.

Important: The official NNAAP skill is called "Measures and Records Urinary Output." The exam tests specifically your ability to measure urine using a graduated container, read the meniscus at eye level, and record the result accurately in milliliters. The urinary output procedure is the tested portion. This page also covers fluid intake measurement because it is a daily CNA responsibility in clinical practice, but the intake portion is additional knowledge beyond what the skills exam evaluates.

Why This Skill Matters on the CNA Exam

The evaluator on the NNAAP exam checks that you put on gloves before handling urine, use correct technique when reading the graduate at eye level, read the meniscus properly, record output in milliliters with a time stamp, and correctly convert meal tray fluid volumes to milliliters for the intake record. Each of these is a discrete check on the evaluator's checklist.

In a real care setting, I&O is critical for patients with heart failure, kidney disease, post-surgical care, or any condition where fluid balance affects treatment decisions. An error in measurement or documentation can lead to missed signs of fluid overload or dehydration. The CNA is often the only person directly observing a patient's fluid consumption at meals and collecting urine output throughout the shift.

Check with your state's testing provider for the specific I&O items included in the skills exam checklist, as the exact scope of what is tested may vary.

Understanding the Equipment

Before measuring output, you need to know what each piece of equipment is for.

Collection hat (specimen hat): A shallow plastic pan that fits inside the toilet bowl or sits on top of it, used to collect urine for measurement from residents who can use the toilet independently. It is shaped somewhat like a hat, which is where the name comes from.
Urinal: A plastic container used for urine collection when a male resident cannot access the toilet, or for bed-bound residents.
Bedpan: A container used to collect urine (and stool) from residents who cannot get out of bed.
Graduate measuring container: A clear plastic container with milliliter markings along the side, used to measure the volume of collected urine. It typically holds 1,000 mL (1 liter) and has markings in increments of 25 or 50 mL.
Meniscus: The curved surface of a liquid in a container. Water and urine curve downward in the center of the container. The correct reading is taken at the lowest point of this curve.

Fluid Equivalents You Need to Know

For intake documentation, you convert container sizes to milliliters using these standard equivalents:

1 cup (8 oz) = 240 mL
1 fluid ounce (fl oz) = 30 mL
1 tablespoon = 15 mL
1 teaspoon = 5 mL
Ice: record as half its volume (an 8 oz cup of ice = 120 mL when melted)

Facilities typically have a reference card listing the volumes for specific serving containers used in their kitchen, such as how many mL are in their standard coffee cup or juice carton. On the NNAAP exam, the scenario may provide the container sizes or ask you to calculate from equivalents directly.

What Counts as Intake

Everything a patient consumes that is liquid at room temperature or that becomes liquid at body temperature counts as intake:

Water, juice, milk, coffee, tea
Soup and broth
Gelatin (Jell-O) and ice cream (they are liquid at body temperature)
Ice chips (recorded as half their volume)
IV fluids and tube feeding fluids (typically documented by nurses, but CNAs should know what counts)

Food that is solid at room temperature (bread, meat, vegetables) is not counted as fluid intake even though food contains water. Only items that are liquid at room temperature or convert to liquid at body temperature are included.

What You Need

Disposable gloves
Graduate measuring container (calibrated in mL)
Urinal, bedpan, or specimen collection hat
Pen
I&O documentation form

Step-by-Step: Measuring Urinary Output

Wash your hands and put on gloves. Before you touch any collection container that holds urine, gloves are required. This is standard precaution for body fluid contact, and the evaluator will mark it as a deduction if you handle urine without gloves. Wash hands first, then put gloves on.
Pour urine from the collection device into the graduate. Carefully pour the urine from the urinal, bedpan, or collection hat into the graduate measuring container. Pour slowly to avoid splashing. If the urine is in a collection hat in the toilet, remove the hat carefully and hold it level until you can pour without spilling.
Set the graduate on a flat, level surface. Place the container on a flat surface such as a counter or the inside of the utility room sink. A tilted surface causes the liquid to pool on one side and makes an accurate reading impossible.
Bring your eyes to the level of the liquid. Crouch or bend so your eyes are at the same height as the fluid line in the graduate. Reading from above causes the measurement to appear lower than it is. Reading from below causes it to appear higher. Eye level with the fluid gives the accurate reading.
Read at the bottom of the meniscus. Look at the curved surface of the urine in the graduate. The liquid curves up slightly where it meets the sides of the container and dips lower in the center. Read the number at the lowest point of that curve, not at the edges where the fluid climbs the wall of the container.
Note the appearance of the urine before discarding. Look at the color, clarity, and note any odor. Normal urine is pale to medium yellow and mostly clear. Document and report any of the following to the nurse: dark or tea-colored urine (possible dehydration or liver issue), cloudy urine (possible infection), blood in the urine (pink, red, or brownish discoloration), or a strongly foul or unusual odor.
Dispose of the urine in the toilet and flush. Pour the measured urine into the toilet. Flush. Rinse the graduate measuring container with cold water. Rinse the collection device (urinal, bedpan, or hat) with cold water and return it to the appropriate storage location or dispose of it if it is single use.
Remove gloves and wash hands. Peel the gloves off using the inside-out technique, discard them in the trash, and wash your hands before touching any documentation materials. Your hands are considered contaminated until washed after glove removal.
Record the output in mL with the time. Write the volume in milliliters on the I&O sheet and note the time of measurement. Using mL as the unit is required. Do not record in ounces or cups on an I&O sheet even if you calculated from those units. The time is important because output is often evaluated per hour or per 8-hour shift.
Report output below 30 mL per hour or below 240 mL per 8-hour shift. These thresholds are the standard reporting criteria for low urinary output. Low output can indicate dehydration, urinary retention, or kidney dysfunction. Report it to the supervising nurse promptly without trying to determine the cause yourself.

Measuring and Recording Fluid Intake

Intake is documented at the time of each meal or fluid delivery. To record intake accurately:

Observe what fluids were on the tray and how much of each was consumed. Note what was NOT finished, because you record only what was actually consumed, not what was offered.
Identify the container sizes. Use standard equivalents or the facility's container reference card to determine the volume of each serving in mL. For example, if the patient drank a full 8 oz glass of juice, that is 240 mL.
For partially consumed servings, estimate the fraction consumed. If half of the glass was drunk, record half the total mL.
For ice chips, record half the volume offered. An 8 oz cup of ice that was fully consumed equals approximately 120 mL of intake.
Add all fluid volumes together and record the total mL for that meal on the I&O sheet with the time.

What the Examiner Looks For

Gloves put on before handling any urine or collection device
Urine poured into graduate without spilling
Graduate placed on a flat surface
Reading taken with eyes at the level of the fluid
Reading taken at the bottom of the meniscus
Urine appearance noted before disposal
Urine disposed of in toilet and collection device rinsed
Gloves removed correctly and hands washed before documentation
Output recorded in mL with time stamp
Intake documented in mL using correct volume equivalents
Ice recorded as half its volume
Abnormal output flagged for reporting to nurse

Common Mistakes to Avoid

Not wearing gloves before handling urine. Some students automatically reach for the collection hat or urinal before they realize they have not gloved up. Build the habit of gloving before you touch anything that has contact with body fluids.
Reading the graduate container from the wrong angle. Standing up and looking down at the graduate is one of the most common errors in this skill. The reading will appear lower than it actually is. Bend down and get your eyes level with the fluid before calling out the number.
Reading the top of the meniscus instead of the bottom. This takes practice to see correctly. The bottom of the curved surface is the accurate reading point. Reading the top edge of the curve (where the liquid climbs the container wall) will overestimate the volume.
Forgetting to record ice as half its volume. This is a commonly tested knowledge point on both the written and practical portions of the NNAAP exam. Ice is not a liquid in the cup, but it counts as fluid intake at half its volume, because that is how much water it becomes when melted.
Recording output in ounces or cups instead of mL. I&O records are always documented in milliliters. Even if you estimated the volume in ounces using a conversion, write the converted mL value on the form, not the ounces figure.
Not reporting abnormal urine appearance. Students focused on the measurement number sometimes set urine aside and discard it without taking a second to observe it. Color, clarity, and odor are clinical findings that must be reported. Make observation a deliberate step before disposal.

Printable Practice Checklist

Use this checklist when practicing. Check off each step as you complete it.

Washed hands
Put on gloves before touching collection device
Poured urine into graduate measuring container
Placed graduate on flat surface
Read measurement at eye level
Read at the bottom of the meniscus
Noted color, clarity, and odor of urine
Disposed of urine in toilet and flushed
Rinsed collection device
Removed gloves using inside-out technique
Washed hands after glove removal
Recorded output in mL with time on I&O sheet
Recorded fluid intake in mL at time of meal
Converted ice to half its volume for intake record
Identified output below 30 mL/hr or 240 mL/8 hrs for reporting
Noted any abnormal urine appearance for reporting

I&O tracking is a daily responsibility in most CNA roles. Find CNA programs near you that include clinical practice with real documentation and measurement tools.

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