NEDOCS Calculator (emergency department overcrowding score)

Understanding the NEDOCS calculator — concept and principle

The National Emergency Department Overcrowding Scale (NEDOCS) turns seven numbers about an emergency department (ED) and its hospital into one score of how crowded the ED is. Hospitals use it to monitor crowding over the day and to trigger surge plans.

ED crowding score: with the default inputs the result is NEDOCS 143 (severely overcrowded).

How it is calculated

NEDOCS = 85.8 × (patients in ED ÷ ED beds) + 600 × (admitted patients waiting ÷ hospital beds) + 13.4 × (ventilated patients in ED) + 0.93 × (longest admitted-patient wait, h) + 5.64 × (arrival-to-bed time of the last patient placed, h) − 20

Levels: 20 or less not busy, 21–60 busy, 61–100 extremely busy but not overcrowded, 101–140 overcrowded, 141–180 severely overcrowded, above 180 dangerously overcrowded. Negative results are read as not busy.

The principle

Weiss and colleagues (2004) asked physicians and nurses in academic EDs to rate how crowded they felt at random moments, recorded many operational measures at the same time, and used regression to find the combination that best matched the ratings. Occupancy and boarding of admitted patients carry the most weight, reflecting that crowding comes mainly from lack of space and blocked flow to the wards.

Worked example

Default inputs: 30 ED beds, 400 hospital beds, 42 patients in the ED, 9 admitted waiting, 1 ventilated, longest wait 8 h, last bed wait 1.5 h.

85.8 × 42 ÷ 30 = 120.12 (occupancy 1.4 per bed).
600 × 9 ÷ 400 = 13.50; 13.4 × 1 = 13.40.
0.93 × 8 = 7.44; 5.64 × 1.5 = 8.46.
NEDOCS = 120.12 + 13.50 + 13.40 + 7.44 + 8.46 − 20 = 142.9 → 143 → Severely overcrowded.

Each point is the calculator re-run with only “Licensed ED beds” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Licensed ED beds	NEDOCS score
7.5	503
15	263
22.5	183
30	143
37.5	119
45	103
60	83

How to read the result

Where does your result fall?

Higher levels usually activate actions such as opening extra space, speeding discharges and moving admitted patients out of the ED. The score was calibrated in academic centres and may read differently in small or rural departments, so local thresholds are common.

Common mistakes

Counting hallway patients but not beds consistently.
Using staffed beds one day and licensed beds another.
Comparing scores across hospitals of very different sizes without caution.

Keep in mind: NEDOCS is an operational tool, not a measure of individual patient risk.

Frequently asked questions

What NEDOCS score means overcrowded?

101–140 is overcrowded, and above 140 severely or dangerously overcrowded.

Why does boarding count so much?

Admitted patients waiting in the ED occupy beds and staff time, blocking new patients.

How often is NEDOCS calculated?

Many hospitals update it every few hours or continuously from their information system.

Sources: Weiss SJ, Derlet R, Arndahl J, et al., "Estimating the degree of emergency department overcrowding in academic medical centers: results of the National ED Overcrowding Study (NEDOCS)", Acad Emerg Med 2004;11(1):38–50

Checked 9 Nov 2026. Weiss SJ, Derlet R, Arndahl J et al., “Estimating the degree of emergency department overcrowding in academic medical centers: results of the National ED Overcrowding Study (NEDOCS)”, Acad Emerg Med 2004;11(1):38–50; formula and levels as documented in Juvare EMResource Help, “NEDOCS Calculation”.

Your numbers