CDN pricing cannot be compared reliably with one advertised per-gigabyte number. A useful estimate applies each provider’s current rate card or proposal to the same traffic, cache, security, and support assumptions.
Build one workload model
Record a representative month and a peak event separately. At minimum include:
- delivered bytes by billing region;
- HTTP and HTTPS request counts;
- cache-hit ratio and bytes fetched from origins or shields;
- purge and configuration-change volume;
- log volume and destination;
- image, video, edge-compute, WAF, bot, and DDoS usage;
- committed traffic, overage, and contract term;
- support tier and required service level.
Use measured traffic where possible. If the application is new, publish the assumptions beside the estimate and run low, expected, and high scenarios.
Normalize charge categories
| Category | Questions to answer |
|---|---|
| Cache egress | Is usage tiered by region, volume, or billing account? |
| Requests | Are requests charged by method, protocol, or region? |
| Cache fill and origin egress | Does the CDN charge fill traffic, and does the origin provider charge egress? |
| Shielding | Is shield traffic a separate charge, and can it reduce origin egress? |
| Purging | Are invalidations included, rate-limited, or charged per path? |
| Logs and analytics | Are delivery, storage, streaming, or query charges separate? |
| Security | Which WAF, bot, rate-limit, and DDoS capabilities require an add-on or plan? |
| Compute | What are the request, execution-time, CPU, and memory units? |
| Support and minimums | Is there a platform fee, traffic commitment, support fee, or minimum invoice? |
| Taxes and currency | Which exchange date, tax treatment, and rounding rules apply? |
Use a dated calculation
A simplified monthly model is:
delivery cost
+ request cost
+ cache-fill and origin-egress cost
+ logs, security, compute, and support
+ overage and minimum commitments
= estimated monthly costStore the source URL, access date, currency, unit convention, regions, and excluded taxes with every rate. Pricing pages change; an undated number is not reproducible.
Do not mix decimal gigabytes and binary gibibytes. Convert all traffic to one unit before applying rates. Apply volume tiers in order rather than multiplying all traffic by the final marginal rate.
Compare proposals fairly
For contracted pricing, ask each vendor to price the same workload sheet and term. Separate discounts from architectural differences. A lower CDN price can still increase total cost if cache fill, cloud-origin egress, logging, or security products are more expensive.
Test the configurations used in the estimate. Different cache keys, TTLs, or shield policies can materially change cache hit ratio and billed origin traffic.
Report a range, not false precision
Publish the expected total and the drivers that move it. Sensitivity tests should include traffic growth, a lower cache-hit ratio, a traffic spike, a region-mix change, and additional security or logging usage. Procurement decisions should also consider reliability, operational effort, support, and exit costs—not price alone.
Use the provider comparison tool to build a capability shortlist before requesting prices. Provider profiles should cite current pricing sources where public rates exist; a blank price is preferable to an invented or stale figure.