Mortality Rate Calculator (death rate, case-fatality and proportionate mortality)

Understanding the mortality rate calculator — concept and principle

This calculator works out a mortality (death) rate per 1,000 or 100,000 people, and optionally the case-fatality rate and proportionate mortality. Students, public health staff and journalists use these measures to describe how many people die from a cause and how deadly a disease is.

Deaths ÷ population: with the default inputs the result is 278.8 (per 100,000).

How it is calculated

Mortality rate = deaths in the period ÷ mid-period population × 10ⁿ

Case-fatality rate (%) = deaths from the disease ÷ number of cases × 100

Proportionate mortality (%) = deaths from one cause ÷ deaths from all causes × 100

Use all deaths for a crude death rate, deaths from one cause for a cause-specific rate, or one age group for an age-specific rate.
Enter 0 for cases or all-cause deaths to skip those measures.

The principle

A rate needs a denominator that reflects the population at risk during the period. The mid-period population is used as an estimate of the average number of people alive and at risk. Multiplying by 1,000 or 100,000 turns a tiny fraction into a readable number. The case-fatality rate uses a different denominator, people with the disease, so it measures severity rather than how common deaths are. Proportionate mortality shows the share of all deaths due to a cause, not the risk of dying.

Worked example

Default inputs: 1,450 deaths, population 520,000, per 100,000, no case or all-cause data.

Mortality rate = 1,450 ÷ 520,000 × 100,000 = 278.85 → 278.8 per 100,000.
Deaths per person = 1,450 ÷ 520,000 = 0.002788.
Case-fatality and proportionate mortality are skipped (—).

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

Mid-period population	Mortality rate
130,000	1,115.4
260,000	557.7
390,000	371.8
520,000	278.8
650,000	223.1
780,000	185.9
1.04e+06	139.4

How to read the result

Compare rates only for the same period length, usually one year, and the same type of rate. Populations with more older people have higher crude death rates even when health is similar, so compare after age standardisation. A high case-fatality rate means a disease is deadly for those who get it, even if it is rare.

Common mistakes

Using the start-of-year population when it changed a lot during the year.
Calling a case-fatality ratio a mortality rate.
Comparing crude rates between populations with different age structures.

Keep in mind: This is a statistical tool. Interpreting differences between places or periods needs attention to data quality and population structure.

Frequently asked questions

What is a crude death rate?

All deaths in a year divided by the mid-year population, usually per 1,000.

Why is case fatality not a true rate?

It has no time in the denominator; it is a proportion of cases who die.

What is age standardisation?

A method that applies age-specific rates to a standard population so that places with different age structures can be compared.

Sources: Centers for Disease Control and Prevention, Principles of Epidemiology in Public Health Practice, 3rd ed., Lesson 3 "Measures of Risk", Section 3 "Mortality Frequency Measures"

Checked 9 Nov 2026. Centers for Disease Control and Prevention, Principles of Epidemiology in Public Health Practice, 3rd edition, Lesson 3 “Measures of Risk”, Section 3 “Mortality Frequency Measures” (crude, cause-specific and age-specific mortality, case-fatality rate, proportionate mortality).

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