Although much work has been done evaluating causes for increased demand for emergency department (ED) services, few ways are available to help determine that an individual ED is overcrowded. Four calculations are proposed using real-time data for accurately diagnosing an ED with potential for failing both as a safety net and as a source for quality health care. The bed ratio (BR) accounts for the number of patients in relation to the available treatment spaces. The BR is obtained by adding the current number of ED patients to the predicted arrivals minus the predicted departures and dividing the result by the total number of treatment spaces. The acuity ratio (AR) measures the relative burden of illness in the ED. The AR is the average triage category of all patients in the ED. The provider ratio (PR) determines the volume of patients that can be evaluated and treated by the physician providers. The PR is found by dividing the arrivals per hour by the sum of the average patients per hour usually disposed for each provider on duty. From these ratios, the demand value (DV) is calculated, which gives an overall measure of current demand. The DV is found by taking the sum of the BR and PR and multiplying by the AR. A DV of more than 7 should initiate a specific assessment of the individual ratios in order to accurately diagnose the problem and institute action. Based on the values, predetermined processes can be instituted to help remedy the overcrowded situation. Trended over time, the ratios can provide the data needed for better resource assessment, planning, and allocation.