Infection Fatality Rate Calculator

Work out infection fatality rate instantly with clear inputs, formula shown and shareable results.

About Infection Fatality Rate Calculator

Scales confirmed cases by an ascertainment multiple to estimate total infections, then divides deaths by that denominator.

Formula

Infection fatality rate

IFR (%) = deaths / (confirmed cases x infections per confirmed case) x 100

Worked example

With the default values below, Infection Fatality Rate Calculator returns Infection fatality rate of 0.5000%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Deathsaccepts 0–10,000,000: 500
Confirmed casesaccepts 1–100,000,000: 20,000
Infections per confirmed caseaccepts 1–50: 5

Results

Infection fatality rate: 0.5000%
Estimated total infections: 100,000
Case fatality rate for comparison: 2.500%
CFR to IFR ratio: 5.00

Step by step

1Values used
2Infection fatality rate
3Infection fatality rate= 0.5000
4Estimated total infections= 100,000
5Case fatality rate for comparison= 2.500
6CFR to IFR ratio= 5.00

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Where does the ascertainment multiple come from?

Seroprevalence surveys, which measure past infection directly and are the standard way to estimate under-ascertainment.

Why is IFR strongly age dependent?

Mortality risk rises roughly exponentially with age for most respiratory infections, so a single IFR hides large variation.