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Free tool · CNML® exam topic

Nurse-to-patient ratio calculator

Enter the census and the ratio you staff to. The calculator rounds up to whole nurses per shift and converts the ratio into RN hours per patient day.

5 for 1:5

h

Example: 26 patients on a medical-surgical unit staffed at 1:5 on 12-hour shifts.

Result

Nurses needed per shift
6
Exact nurse count
5.20
RN hours per patient day at this ratio
4.8

26 patients ÷ 5 = 5.20, rounded up to 6 nurses per shift. Holding 1:5 around the clock gives each patient 4.8 RN hours a day.

Ratio math

  • Nurses per shift = patients ÷ patients per nurse, rounded up
  • RN HPPD implied by the ratio = 24 ÷ patients per nurse

Worked example

26 patients at 1:5: 26 ÷ 5 = 5.20, so the shift needs 6 nurses. A 1:5 ratio held for 24 hours gives each patient 4.8 RN hours a day; the six nurses actually on shift give a little more, because of the rounding.

Ratios, HPPD and the budget

Ratios set the minimum staff on a shift; HPPD measures the hours actually worked against patient days. Most budgets are built on HPPD, so check the result with the HPPD calculator and size the positions with theFTE calculator. Where a state sets mandatory ratios, follow the regulation for your unit type.

Test yourself: a CNML-style question

A unit staffs RNs at a 1:4 ratio around the clock. How many RN hours per patient day does this ratio provide?

  1. 4.0
  2. 4.8
  3. 6.0
  4. 8.0
Show answer

C. 6.0

Each nurse covers 4 patients, so each patient receives 1/4 of a nurse for 24 hours: 24 ÷ 4 = 6.0 RN hours per patient day.

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 many nurses do I need for a 1:5 ratio?
Divide the number of patients by 5 and round up. 26 patients at 1:5 need 26 ÷ 5 = 5.2, rounded up to 6 nurses per shift.
How does a ratio convert to HPPD?
If a ratio is held for all 24 hours, each patient gets 24 ÷ (patients per nurse) RN hours a day. A 1:4 ratio equals 6.0 RN HPPD, and 1:5 equals 4.8. Unit HPPD is higher once charge nurses, LPNs and assistive staff are added.
Why round up?
Nurses come in whole people per shift. Any fraction above a whole number means at least one nurse would carry more patients than the ratio allows.

Sources

  1. American Nurses Association. Nurse staffing measures
  2. CDC NHSN. Nurse Staffing Hours Indicator protocol (Nursing Hours per Patient Day), August 2023

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.

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