CDN Bandwidth Cost Calculator
Estimate monthly CDN egress cost from your traffic — average object size, requests per month and the per-GB data-transfer rate.
How it works
Data (GB) = requests × object KB ÷ 1,000,000 · Origin data = data × (1 − hit%) · Total = data × CDN $/GB + origin data × origin $/GB
CDN cost is driven by total bytes delivered, so the average object size matters as much as the request count — halving image weight halves the bill. A high cache hit ratio keeps most requests on the cheaper edge network and away from your origin; every cache miss has to be fetched from origin, adding a second egress charge on top. Raising the hit ratio and shrinking payloads are the two most effective ways to bring the number down.
Worked example
Five million requests of 250 KB deliver 5,000,000 × 250 ÷ 1,000,000 = 1,250 GB. CDN egress at $0.085/GB is $106.25. With a 90% hit ratio, 10% (125 GB) is fetched from origin at $0.09/GB = $11.25, for a total near $117.50 a month.
Frequently asked questions
Why does the cache hit ratio matter for cost?
Requests served from the CDN edge are cheaper and faster than ones that miss and must be pulled from your origin. A miss incurs both the edge delivery charge and an origin egress charge, so raising the hit ratio cuts the origin bill and speeds up responses at the same time.
Should I use decimal (1000) or binary (1024) for GB?
Cloud and CDN providers bill in decimal gigabytes, where 1 GB = 1,000,000 KB, so this calculator uses 1,000-based conversion to match your invoice. Binary units (GiB, 1024-based) are for memory and disk, not network billing.
Does this include request fees?
No — it prices data transfer (egress) only. Many CDNs also charge a small fee per 10,000 requests and may bill by region; add those separately if your provider itemises them.
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This calculator is for educational purposes. Double-check important results before acting on them.