Work out cdn cost instantly with clear inputs, formula shown and shareable results.
CDN cost has three components: delivery to end users, request charges, and origin egress for the misses. The hit rate controls the third, which is billed at full origin egress rates — so improving the hit rate from 92 to 98 percent cuts origin cost by three quarters even though delivery volume is unchanged.
CDN cost
delivery = TB x 1000 x CDN rate; requests = requests / 10000 x request rate; origin = TB x 1000 x (1 - hit rate) x origin egress rate
Longer TTLs, cache keys that ignore irrelevant query parameters and cookies, and origin shielding so multiple edge locations do not each fetch the same object.
Almost always for public content, both because per-gigabyte rates are lower and because the hit ratio removes most origin traffic. Committed-volume contracts reduce it further.