Centor Score Calculator (Modified/McIsaac)

Created by Łukasz Białek, MD
Reviewed by Bogna Szyk
Based on research by
Centor RM, Witherspoon JM, Dalton HP, Brody CE, Link K. The diagnosis of strep throat in adults in the emergency room. Medical Decision Making (1981)
Last updated: Jul 19, 2022

Centor score estimates the probability that pharyngitis is caused due to streptococcal infection. It is based on Centor criteria (modified/McIsaac) which consist of five simple clinical data.

Keep on reading to find out:

  • What is the basis of Centor criteria?
  • How to calculate Centor score?
  • What does the result of Centor score tell you?

What is the basis of Centor criteria?

In 1981, Dr. Robert Centor with associates published an article in Medical Decision Making. Its goal was to see if clinical findings could stratify the probability that an adult patient with a sore throat had group A Streptococcus. They analyzed 234 patients who filled their questionnaire and had throat culture performed. They noticed that the set of four variables could decently predict the positive culture. Almost two decades later, Dr. Warren McIsaac modified the scale adding the fifth variable - age.

How to calculate Centor score?

The Centor (Modified/McIsaac) criteria is a kind of strep throat criteria and consist of four variables: fever >38 Celsius, tonsillar exudates, tender anterior cervical lymphadenopathy and the absence of cough. Each of them may give you +1 point. The fifth variable - age - may give you -1, 0, or +1 point.

Body temperature Fever >38 C / 100.4 F 1
No fever nor feverishness 0
Tonsils Tonsillar exudates 1
No exudate 0
Lymph Nodes Lymphadenopathy 1
No lymphadenopathy 0
Cough Cough 0
No Cough 1
Age <15 1
16-44 0
>45 -1

What does the result of Centor score tell you?

The greater the Centor score, the bigger the probability of streptococcal infection causing the pharyngitis.

Centor score Probability of positive culture
4 or 5 51-53 %
3 28-35 %
2 14-16 %
1 5-7 %
0 1-3 %

This is why the interpretation of Centor score should be as follows:

  • 0-1 point: no further testing or antibiotics required.
  • 2-3 points: culture test should be taken, antibiotics only needed with positive culture results.
  • 4-5 points: treat empirically with antibiotics.

Let's get an example!

A 24-year-old male student came to the doctor due to a sore throat, which started on the day before the visit. The patient also reports productive cough, sneezing, and a runny nose. His body temperature is 37.8 Celcius. He denies pain on the neck. On medical examination there are enlarged, swollen tonsils with exudate. However there is no lymphadenopathy.

To assess appropriate patient management concerning possible bacterial etiology of pharyngitis a doctor should calculate the Centor score. The patient receives: body temperature - 0 points, tonsils - 1 point, lymph nodes - 0 points, cough - 0 points and age - 0 points. Altogether - 1 point. In this case no antibiotic or throat culture is necessary, as the risk of streptococcal infection is 5-7%.


Using any calculator may never replace medical examination. If you feel any symptoms, contact your physician!

Łukasz Białek, MD
Body temperature
Lymph nodes
Centor Score
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