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# Mortality rates: crude and specific

- Measure

They count how many people die in a population over a period. The crude rate looks at everyone; specific rates look at one age group, sex or cause.

Updated Nov 5, 2026

## Key points

- Crude rate = total deaths / mid-period population × 1,000 (or × 100,000).
- In an age- or sex-specific rate, numerator and denominator are limited to the same group.
- A cause-specific rate uses the whole population as denominator; proportional mortality uses all deaths.
- An older population can have a high crude rate while being healthier: to compare, standardise by age.
- High proportional mortality does not mean high risk: it can rise just because other causes fell.

On this page

- The basics Key points
- What it is
- Formula and reading
- Worked example
- What goes on top and what goes below in each measure
- Markers
- How to read it
- Common pitfalls
- Memory aid

- Study Test yourself

- Connections Connections

## What it is

The crude mortality rate divides all deaths in a period by the mid-period population. Specific rates restrict both numerator and denominator to the same group (age, sex), or restrict the numerator to one cause. Proportional mortality is not a rate: it is the share of all deaths that belongs to one cause.

## Formula and reading

- Crude rate = (deaths from all causes in the period / mid-period population) × 10ⁿ.
- Age-specific rate = (deaths in the age group / population of that group) × 10ⁿ.
- Cause-specific rate = (deaths from the cause / total mid-period population) × 100,000.
- Proportional mortality = (deaths from the cause / all deaths) × 100, as a percentage.
- The mid-period population (for example, on 30 June) approximates the person-years lived during the year.

## Worked example

- A made-up municipality has 80,000 people at mid-year (39,000 men and 41,000 women) and records 560 deaths in the year.
- Crude rate: 560 / 80,000 = 0.007; × 1,000 = 7.0 deaths per 1,000 population.
- By sex: 308 deaths in men / 39,000 = 7.9 per 1,000; 252 in women / 41,000 = 6.1 per 1,000 (rounded to one decimal).
- By age: 6,000 people are 65 or older and 312 of the deaths occur among them: 312 / 6,000 × 1,000 = 52 per 1,000.
- By cause: 168 deaths are cardiovascular: 168 / 80,000 × 100,000 = 210 per 100,000 population.
- Cardiovascular proportional mortality: 168 / 560 = 0.30, that is, 30% of all deaths.
- Reading: the risk of dying at 65 or older is more than seven times the overall rate, and three in ten deaths are cardiovascular.

## What goes on top and what goes below in each measure

| Measure | Numerator | Denominator | Usual multiplier |
| --- | --- | --- | --- |
| Crude rate | All deaths | Total mid-period population | 1,000 or 100,000 |
| Age-specific | Deaths in that age group | Population of that age group | 1,000 or 100,000 |
| Sex-specific | Deaths in that sex | Population of that sex | 1,000 or 100,000 |
| Cause-specific | Deaths from that cause | Total mid-period population | 100,000 |
| Proportional mortality | Deaths from that cause | All deaths | 100 (percentage) |

## Markers

- CDR
- Specific rate
- Proportional mortality
- × 100,000

## How to read it

- Age-specific rates are the raw material of standardisation and of life tables.
- In Colombia, deaths come from the death certificates that doctors fill in; their quality sets the quality of cause-specific rates.

## Common pitfalls

- Using total deaths as the denominator and calling it a rate: that is proportional mortality.
- Comparing crude rates of populations with different age structures without standardising.
- Forgetting the multiplier, or mixing ‘per 1,000’ with ‘per 100,000’ when comparing.

## Memory aid

A rate looks at the living, a proportion looks at the dead: if the denominator is deaths, it is no longer a rate.

## Test yourself

Think of the answer, then tap the question to see it.

## What denominator does the cause-specific mortality rate use?

The total mid-period population; the numerator is only the deaths from that cause.

## How does proportional mortality differ from a rate?

Its denominator is all deaths, not the population; it says what share of deaths belongs to a cause, not the risk of dying from it.

## Why can a city with many older adults have a high crude rate without worse health?

Because mortality rises with age; the crude rate reflects the age structure. Comparisons use specific or standardised rates.

## If a population of 20,000 has 50 deaths in a year, what is the crude rate per 1,000?

50 / 20,000 × 1,000 = 2.5 deaths per 1,000 population.

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## Connections

## Related 6

- [Standardisation of rates](https://durgical.com/en/epidemiology/standardisation-of-rates/)
- [Case fatality rate](https://durgical.com/en/epidemiology/case-fatality-rate/)
- [Infant, neonatal and perinatal mortality](https://durgical.com/en/epidemiology/infant-neonatal-and-perinatal-mortality/)
- [Years of potential life lost](https://durgical.com/en/epidemiology/years-of-potential-life-lost/)
- [Incidence](https://durgical.com/en/epidemiology/incidence/)
- [Life expectancy](https://durgical.com/en/epidemiology/life-expectancy/)

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Educational content on epidemiological and statistical methods; the examples use made-up numbers to teach the calculation. Not a clinical or legal guide: current Colombian rules are in the official sources.

Sources: [Principles of Epidemiology | Lesson 3 - Section 3](https://archive.cdc.gov/www_cdc_gov/csels/dsepd/ss1978/lesson3/section3.html) (Centers for Disease Control and Prevention, 2012); [Age adjustment](https://www.cdc.gov/nchs/hus/sources-definitions/age-adjustment.htm) (National Center for Health Statistics, Centers for Disease Control and Prevention, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/epidemiology/mortality-rates-crude-and-specific/