One Percentage Point of Cache Hit Rate Changes Your Bill
Adding a CDN doesn't automatically save money — the actual impact depends entirely on your cache hit rate. At a 70% hit rate, the remaining 30% of requests still reach your origin server, adding processing load and data transfer costs. Pushing that hit rate to 90% alone cuts the requests your origin has to handle by two-thirds.
This calculator applies the gap between your current and target hit rate to your monthly request volume and average response size to estimate how many requests and how much data transfer you'll shift away from the origin, then multiplies that by your per-GB transfer cost.
To raise your hit rate, start by setting generous cache TTLs for static assets and cleaning up cookies or unnecessary query parameters that fragment your cache keys. If the estimated savings come out large, that's solid justification for investing in better cache policy work.
Frequently Asked Questions
It is the share of total requests served directly from the CDN cache. A low hit rate means more requests reach your origin server, adding load and cost.
Common fixes include extending cache TTLs appropriately, avoiding cache key fragmentation from cookies or query parameters, and separating cache policies for static assets versus dynamic content.
Use the data transfer out (egress) rate listed by your actual CDN or cloud provider for the most accurate savings estimate.