Calculate case fatality rate or mortality (death) rate from deaths and cases or population, plus infant, maternal and workplace fatality rates.

Use counts and denominators for the same population and period.

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Fatality Rate Formulas (Population, Case, and Workforce)

“Fatality rate” is used in different ways. Depending on context, one of the following formulas may be appropriate:

Population death proportion (%) = (D) / (P) × 100\ Population death rate (per N) = (D) / (P) × N\ Case fatality rate (CFR, %) = (Dc) / (C) × 100\ Workforce fatality rate (per 100,000 FTE) = (Dw) / (H) × 200,000,000

Variables:

  • D is the number of deaths in the population during the period
  • P is the population size (often the mid-period/average population) for that period
  • N is the rate base (e.g., 1,000; 100,000; 1,000,000)
  • Dc is the number of deaths among cases
  • C is the total number of cases
  • Dw is the number of fatal work injuries
  • H is the total hours worked during the same reporting period and for the same worker group (the factor 200,000,000 = 100,000 FTE-years × 2,000 hours per FTE-year)

Dividing deaths by the total population produces a population-based mortality measure (often reported “per 100,000” for a stated period and sometimes annualized). Dividing deaths by cases produces a case fatality rate (CFR), which is commonly what “fatality rate” refers to in outbreak and clinical settings.

What is a Fatality Rate?

A fatality rate most commonly refers to the case fatality rate (CFR): the percentage of identified cases (people with the disease/condition or exposed in an incident) who die from it over a defined period. In other contexts, people use “fatality rate” to mean a population-based death rate/proportion (deaths divided by the total population), which is a mortality measure and is typically reported per 1,000 or per 100,000 for a specified time period.

How to Calculate Fatality Rate?

Choose the measure and the value to find, then enter the relevant known inputs. Implied counts are unrounded estimates, not observed counts. Population annualization assumes a representative population throughout the period. The following steps outline the direct rate calculations:

  1. Decide which measure you want: a population-based death measure, a case fatality rate (CFR), or a workforce fatality rate.
  2. For a population-based measure, determine deaths (D), population size (P), and the time period (so the result can be interpreted “for that period” and optionally annualized).
  3. Compute a population death proportion as (D / P) × 100, or a population death rate as (D / P) × N for a chosen base (e.g., per 100,000).
  4. For CFR, determine deaths among cases (Dc) and total cases (C), then compute (Dc / C) × 100.
  5. For workforce fatality rate, determine fatal work injuries (Dw) and total hours worked (H), then compute (Dw / H) × 200,000,000 per 100,000 FTE worker-years.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Number of deaths (D) = 50

Population size (P) = 10,000

Population death proportion = (50 / 10,000) × 100 = 0.5% (equivalently, 500 per 100,000 for the period).