Infection Fatality Rate Calculator

Calculator

Fields are optional unless marked required.

Deaths

Count of deaths attributable to the infection.

Confirmed infections

Reported cases; often underestimates infections.

Estimated infections

Use model-based or survey-based infection estimates.

Infection source

Choose how infections are derived.

Infection multiplier

Adjust infections for under-ascertainment (≥ 1).

Confidence level

Wilson interval on IFR proportion.

Used when source is set to serology (or auto fallback).

Population

Population size covered by the serosurvey.

Observed seroprevalence (%)

Percent positive in the serology sample.

Test sensitivity (%)

Probability the test detects true positives.

Test specificity (%)

Probability the test rejects true negatives.

Decimal places

Controls rounding for displayed results.

Scenario	Deaths	Infections (estimated)	Multiplier	IFR (%)
Baseline counts	125	250,000	1.00	0.050
Under-ascertainment adjustment	125	250,000	1.50	0.033
Higher deaths, same infections	220	250,000	1.00	0.088

These rows are illustrative and not tied to any specific outbreak.

IFR (proportion): IFR = deaths / infections
IFR (%): IFR% = (deaths / infections) × 100
IFR per 1,000 infections: IFR₁₀₀₀ = (deaths / infections) × 1000
Serology infections (Rogan–Gladen correction): truePrev = (obsPrev + spec − 1) / (sens + spec − 1), then infections = truePrev × population.
Uncertainty: Wilson score interval on the IFR proportion using confidence level z.

For intervals, infections are rounded to an integer trial count.