Incidence Rate Calculator for Diseases

Incidence Rate Calculator

Public Health & Epidemiology Analytics

Number of new occurrences of the disease.

Total population susceptible to the disease.

Per 1,000 people Per 10,000 people Per 100,000 people Per 1,000,000 people

Calculation Results

Incidence Rate: 0

Understanding Disease Incidence Rate

In epidemiology, the Incidence Rate is a measure of the frequency with which a disease or other incident occurs over a specified period. It provides an assessment of the probability of developing a condition within a particular time frame, making it a crucial metric for tracking disease outbreaks and the effectiveness of public health interventions.

The Incidence Formula

The standard formula used in this calculator is:

Incidence Rate = (New Cases / Population at Risk) × Multiplier

Incidence vs. Prevalence

It is important not to confuse incidence with prevalence:

• Incidence: Refers only to new cases during a specific period. It measures risk.
• Prevalence: Refers to all existing cases (new and old) at a specific point in time. It measures the burden of the disease on a community.

Practical Example

Imagine a city with a population of 50,000 people at risk. Over the course of 2023, 150 people were diagnosed with a specific respiratory illness.

1. New Cases: 150
2. Population at Risk: 50,000
3. Calculation: (150 / 50,000) = 0.003
4. Rate per 100,000: 0.003 × 100,000 = 300

The incidence rate for the city is 300 cases per 100,000 people per year.

function calculateIncidence() { var cases = parseFloat(document.getElementById('newCases').value); var population = parseFloat(document.getElementById('popAtRisk').value); var multiplier = parseFloat(document.getElementById('multiplier').value); var resultContainer = document.getElementById('resultContainer'); var incidenceValue = document.getElementById('incidenceValue'); var interpretation = document.getElementById('interpretation'); if (isNaN(cases) || isNaN(population) || population <= 0) { alert('Please enter valid positive numbers. Population must be greater than zero.'); return; } var rate = (cases / population) * multiplier; var formattedRate = rate.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 }); var multiplierText = document.getElementById('multiplier').options[document.getElementById('multiplier').selectedIndex].text; incidenceValue.innerHTML = formattedRate + ' (' + multiplierText + ')'; interpretation.innerHTML = 'This means for every ' + multiplier.toLocaleString() + ' people in the population at risk, there were approximately ' + formattedRate + ' new cases identified during the observation period.'; resultContainer.style.display = 'block'; resultContainer.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }