.cache-calc-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e1e4e8;
border-radius: 12px;
background-color: #ffffff;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.cache-calc-container h2 {
color: #1a73e8;
margin-top: 0;
text-align: center;
font-size: 24px;
}
.calc-row {
margin-bottom: 20px;
}
.calc-row label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #3c4043;
}
.calc-row input {
width: 100%;
padding: 12px;
border: 2px solid #dadce0;
border-radius: 6px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.2s;
}
.calc-row input:focus {
border-color: #1a73e8;
outline: none;
}
.calc-btn {
width: 100%;
background-color: #1a73e8;
color: white;
padding: 14px;
border: none;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.2s;
}
.calc-btn:hover {
background-color: #1557b0;
}
#cacheResultArea {
margin-top: 25px;
padding: 20px;
background-color: #f8f9fa;
border-radius: 8px;
display: none;
}
.result-item {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
border-bottom: 1px solid #dee2e6;
padding-bottom: 5px;
}
.result-label {
color: #5f6368;
font-weight: 500;
}
.result-val {
color: #202124;
font-weight: 700;
font-size: 18px;
}
.hit-high { color: #1e8e3e; }
.hit-low { color: #d93025; }
.article-section {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #3c4043;
}
.article-section h3 { color: #202124; border-bottom: 2px solid #1a73e8; display: inline-block; }
function calculateCachePerformance() {
var hits = parseFloat(document.getElementById('cacheHits').value);
var misses = parseFloat(document.getElementById('cacheMisses').value);
var resultArea = document.getElementById('cacheResultArea');
var totalReqDisplay = document.getElementById('totalReq');
var hitRateDisplay = document.getElementById('hitRate');
var missRateDisplay = document.getElementById('missRate');
var msgDisplay = document.getElementById('performanceMsg');
if (isNaN(hits) || isNaN(misses) || hits < 0 || misses = 90) {
hitRateDisplay.className = "result-val hit-high";
msgDisplay.innerText = "Excellent Cache Efficiency!";
msgDisplay.style.color = "#1e8e3e";
} else if (hitRate >= 70) {
hitRateDisplay.className = "result-val";
msgDisplay.innerText = "Good Cache Performance.";
msgDisplay.style.color = "#f9ab00";
} else {
hitRateDisplay.className = "result-val hit-low";
msgDisplay.innerText = "Low Cache Efficiency – Optimization Recommended.";
msgDisplay.style.color = "#d93025";
}
resultArea.style.display = "block";
}
Understanding Cache Hit Rate
Cache Hit Rate is a critical metric used in computer science and web development to measure the effectiveness of a caching system. It represents the percentage of content requests that are successfully served from the cache rather than requiring a fetch from the primary data source (like a database or an origin server).
A higher hit rate indicates that your cache is successfully storing the data users frequently request, leading to faster load times, reduced server load, and lower latency.
The Cache Hit Rate Formula
To calculate the cache hit rate manually, you use the following mathematical formula:
Cache Hit Rate = (Cache Hits / (Cache Hits + Cache Misses)) * 100
- Cache Hit: When the requested data is found in the cache.
- Cache Miss: When the requested data is not in the cache and must be retrieved from the source.
- Total Requests: The sum of all hits and misses.
Why is Cache Hit Rate Important?
In the context of Content Delivery Networks (CDNs) and web performance, the cache hit rate directly correlates with user experience. If your hit rate is 95%, it means 95% of your users are getting content delivered from the "edge," which is much closer to them geographically than your central server.
Low hit rates can be caused by:
- Short Time-to-Live (TTL) settings.
- Frequently changing content that invalidates the cache.
- Insufficient cache storage capacity.
- Large numbers of unique, long-tail URLs.
Example Calculation
Imagine your website receives 1,000 requests for an image. If the CDN serves that image 850 times from its storage and has to ask your origin server for it 150 times, the calculation would look like this:
Total Requests: 850 (hits) + 150 (misses) = 1,000
Hit Rate: (850 / 1,000) * 100 = 85%
Miss Rate: (150 / 1,000) * 100 = 15%
How to Improve Your Hit Rate
If your results from the calculator above are in the red zone (below 70%), consider increasing your Cache-Control max-age headers. This allows files to stay in the cache longer. Additionally, ensure you are not using unique query strings for static assets, as style.css?v=1 and style.css?v=2 are often treated as different files, causing unnecessary cache misses.