Cache Hit Ratio Calculator
Find cache hit and miss ratios.
Results update as you type.
How it works
A cache stores frequently used data so it can be served quickly, and the hit ratio measures how effective it is — this calculator computes it. You enter the number of cache hits (requests served from the cache) and misses (requests that had to fetch from the slower source), and it returns the hit ratio and miss ratio as percentages. The hit ratio is hits divided by total requests, and the miss ratio is the rest. A high hit ratio means most requests are served from the fast cache, which improves performance and reduces load on the underlying database, disk, or network; a low hit ratio means the cache is often bypassed, negating its benefit. What counts as good depends on the system: web and CDN caches often aim for 90 percent or higher, CPU caches exceed 95 percent, and database query caches vary. If your hit ratio is low, you might increase the cache size, adjust the eviction policy (which decides what to remove when full), extend how long items are cached, or improve which data gets cached. Because a cache miss is much slower than a hit, even small hit-ratio improvements can noticeably speed up a system. This calculator helps you monitor and tune cache performance. Enter the hits and misses to find the hit ratio.
Hit ratio = hits ÷ (hits + misses) × 100
The cache hit ratio is the number of hits divided by the total number of requests (hits plus misses), expressed as a percentage. The miss ratio is the complement. A higher hit ratio means the cache serves more requests directly, improving performance.
Source:Caching performance
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter cache hits and cache misses.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Hit ratio updates instantly as you type — no button to press.
Frequently asked questions
How do you calculate cache hit ratio?
Divide the number of cache hits by the total number of requests (hits plus misses), then multiply by 100 for a percentage. With 900 hits and 100 misses, the hit ratio is 90 percent and the miss ratio is 10 percent. A higher hit ratio means the cache is serving more requests directly, which improves performance.
What is a good cache hit ratio?
It depends on the system. Web and CDN caches often target 90 percent or higher, CPU caches typically exceed 95 percent, and application or database caches vary by workload. Generally, higher is better, but the ideal depends on data access patterns. A consistently low ratio signals the cache isn't helping much and should be tuned.
Why does the hit ratio matter?
A cache hit is served quickly from fast memory, while a miss requires fetching from a slower source like a disk, database, or network, which can be orders of magnitude slower. A higher hit ratio means more requests take the fast path, reducing latency and load on backend systems. Even small improvements can significantly boost overall performance.
How can I improve a low hit ratio?
Options include increasing the cache size so more data fits, tuning the eviction policy that decides what to remove when full, lengthening the time-to-live so items stay cached longer, and caching the most frequently accessed data. Analyzing access patterns helps you cache what is actually reused, which is the most effective way to raise the hit ratio.
What is cache eviction?
Eviction is how a cache decides which items to remove when it is full and needs room for new data. Common policies include LRU (least recently used), which removes the item unused for the longest time, and LFU (least frequently used). A good eviction policy keeps the most valuable data cached, directly affecting the hit ratio and performance.