How do you calculate average daily census?

Divide the total patient days in a period by the number of days in that period. A unit with 9,500 patient days in a year has an average daily census of 9,500 ÷ 365 = 26.0.

How do you calculate the occupancy rate?

Divide the average daily census by the number of staffed beds and multiply by 100. An ADC of 26.0 on a 40-bed unit is 65% occupancy.

How do you calculate average length of stay?

Divide patient days by the number of discharges in the same period. 9,500 patient days and 2,100 discharges give an average length of stay of about 4.5 days.

How are patient days counted?

Count the patients on the unit at the same time every day, usually at midnight, and add the daily counts for the period. Each patient on the unit at the census time is one patient day.

Free tool · CNML® exam topic

Average daily census calculator

Patient days ÷ days in the period gives the average daily census. Add beds and discharges for occupancy and average length of stay.

Result

Average daily census: 26.0
Occupancy rate: 65.1%
Average length of stay: 4.5 days

9,500 patient days ÷ 365 days = an average of 26.0 patients a day.

Census formulas

Average daily census (ADC) = patient days ÷ days in the period
Occupancy rate = ADC ÷ staffed beds × 100
Average length of stay (ALOS) = patient days ÷ discharges

Worked example

The first sample question in the AONL CNML handbook gives a year of patient data for a 40-bed unit, 9,500 in total, and asks for the average daily census: 9,500 ÷ 365 = 26.0. On 40 beds, that is 65.1% occupancy. With 2,100 discharges, the average stay is 4.5 days.

Why census drives the budget

Census is the volume statistic behind a unit’s staffing budget: target HPPD × ADC gives the nursing hours needed each day. Carry your ADC into the nurse staffing FTE calculator to see the positions it takes.

Test yourself: a CNML-style question

A 40-bed unit had 9,500 patient days last year. What was its average daily census?

24.0
26.0
29.4
31.7

Show answer

B. 26.0

Average daily census = patient days ÷ days in the period = 9,500 ÷ 365 = 26.0. This mirrors the first sample question in the AONL CNML handbook.

Questions like this come up in the Business Skills and Principles domain of the CNML® exam. The 361 questions in the app each come with a written explanation.

FAQ

How do you calculate average daily census?: Divide the total patient days in a period by the number of days in that period. A unit with 9,500 patient days in a year has an average daily census of 9,500 ÷ 365 = 26.0.
How do you calculate the occupancy rate?: Divide the average daily census by the number of staffed beds and multiply by 100. An ADC of 26.0 on a 40-bed unit is 65% occupancy.
How do you calculate average length of stay?: Divide patient days by the number of discharges in the same period. 9,500 patient days and 2,100 discharges give an average length of stay of about 4.5 days.
How are patient days counted?: Count the patients on the unit at the same time every day, usually at midnight, and add the daily counts for the period. Each patient on the unit at the census time is one patient day.

Sources

Checked against these sources on November 3, 2026. For education and CNML® exam preparation only — not a substitute for your organization’s finance, HR and staffing policies or its official reports. Calculations run in your browser; nothing you enter is sent anywhere.