body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-wrapper {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 25px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calculator-title {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 1.5rem;
font-weight: 700;
}
.input-group {
margin-bottom: 20px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #495057;
}
.input-group input {
width: 100%;
padding: 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.15s ease-in-out;
}
.input-group input:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0,123,255,0.1);
}
.calc-btn {
width: 100%;
padding: 14px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: 600;
cursor: pointer;
transition: background-color 0.2s;
}
.calc-btn:hover {
background-color: #0056b3;
}
.result-box {
margin-top: 25px;
padding: 20px;
background-color: #ffffff;
border: 1px solid #dee2e6;
border-radius: 4px;
text-align: center;
display: none;
}
.result-value {
font-size: 2.5rem;
font-weight: 700;
color: #2c3e50;
margin: 10px 0;
}
.result-label {
color: #6c757d;
font-size: 0.9rem;
text-transform: uppercase;
letter-spacing: 1px;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.article-content p {
margin-bottom: 15px;
}
.article-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.article-content li {
margin-bottom: 8px;
}
.formula-box {
background-color: #eef2f7;
padding: 15px;
border-left: 4px solid #007bff;
font-family: monospace;
font-size: 1.1em;
margin: 20px 0;
}
.error-msg {
color: #dc3545;
font-size: 0.9em;
margin-top: 5px;
display: none;
}
function calculateCrimeRate() {
// Get input values
var homicidesInput = document.getElementById('numHomicides');
var populationInput = document.getElementById('totalPopulation');
var resultBox = document.getElementById('resultBox');
var rateResult = document.getElementById('rateResult');
var popError = document.getElementById('popError');
// Parse values
var homicides = parseFloat(homicidesInput.value);
var population = parseFloat(populationInput.value);
// Validation
var isValid = true;
if (isNaN(homicides) || homicides < 0) {
homicidesInput.style.borderColor = "#dc3545";
isValid = false;
} else {
homicidesInput.style.borderColor = "#ced4da";
}
if (isNaN(population) || population <= 0) {
populationInput.style.borderColor = "#dc3545";
popError.style.display = "block";
isValid = false;
} else {
populationInput.style.borderColor = "#ced4da";
popError.style.display = "none";
}
if (!isValid) {
resultBox.style.display = "none";
return;
}
// Calculation Formula: (Incidents / Population) * 100,000
var rate = (homicides / population) * 100000;
// Display Result
rateResult.innerHTML = rate.toFixed(2);
resultBox.style.display = "block";
}
Understanding Murder Rate Calculation
In criminology, sociology, and urban planning, comparing raw crime numbers between two locations can be misleading. A large city with millions of residents will naturally have more incidents than a small town, even if the small town is actually more dangerous relative to its size. To solve this, statisticians use the Murder Rate, typically standardized as the number of incidents per 100,000 people.
The Calculation Formula
The standard formula used by organizations like the FBI (Uniform Crime Reporting) and the UNODC is relatively simple. It normalizes the data to a standard population block of 100,000.
Rate = (Number of Homicides ÷ Total Population) × 100,000
This creates a metric that allows for fair comparison between a small town of 5,000 people and a metropolis of 8 million.
How to Use This Calculator
Using the tool above provides an instant statistical analysis of crime density:
- Number of Homicides: Enter the total number of murder or non-negligent manslaughter incidents recorded in a specific time period (usually one year).
- Total Population: Enter the census population count for the specific area (city, county, or country) where the incidents occurred.
- Result: The calculator outputs the rate per 100,000 residents.
Example Scenarios
To understand why rates matter more than raw totals, consider these two hypothetical cities:
City A (The Metropolis)
- Population: 2,000,000
- Murders: 100
- Calculation: (100 ÷ 2,000,000) × 100,000 = 5.0 per 100k
City B (The Small Town)
- Population: 25,000
- Murders: 5
- Calculation: (5 ÷ 25,000) × 100,000 = 20.0 per 100k
Even though City A had 20 times more murders than City B, City B actually has a murder rate that is four times higher. A resident in City B is statistically at greater risk than a resident in City A.
Why per 100,000?
While percentages are common in other fields (per 100), crime events are statistically rare events in the general population. Expressing a murder rate as 0.005% is difficult for the average person to visualize. Using a "per 100,000" baseline creates whole numbers (like 5.0) that are easier to read, compare, and track over time.
Factors Influencing Rates
When analyzing these statistics, keep in mind that rates can fluctuate significantly in areas with very small populations. In a town of 1,000 people, a single incident can cause the rate to spike to 100 per 100k, which may be a statistical anomaly rather than a trend. Criminologists often look at multi-year averages for smaller jurisdictions to account for this volatility.