CDN Throughput and Bandwidth Calculation
Calculate CDN bandwidth requirements for websites and applications. Estimate peak throughput, monthly data transfer, and CDN cost based on traffic patterns.
Network Planning
Detailed Explanation
CDN Bandwidth Calculation
Content Delivery Networks serve cached content from edge locations worldwide. Properly sizing CDN bandwidth prevents slow page loads and unexpected cost overruns.
Estimating CDN Bandwidth
The key formula:
Peak bandwidth = Peak concurrent users * Average page size * Pages per minute / 60
Example: E-Commerce Site
For an e-commerce site during Black Friday:
Peak concurrent users: 10,000
Average page size (with images): 3 MB
Pages per minute per user: 2
Peak bandwidth = 10,000 * 3 MB * 2 / 60
= 1,000 MB/s = 8 Gbps
Monthly Data Transfer
Daily unique visitors: 100,000
Average pages per visit: 5
Average page size: 3 MB
Cache hit ratio: 85%
Total served: 100,000 * 5 * 3 MB = 1,500 GB/day
CDN serves: 1,500 * 0.85 = 1,275 GB/day
Monthly CDN egress: 1,275 * 30 = 38.25 TB
CDN Pricing Comparison
| Provider | First 10 TB/mo | 10-50 TB/mo |
|---|---|---|
| CloudFlare Pro | Included | Included |
| AWS CloudFront | $0.085/GB | $0.080/GB |
| Fastly | $0.12/GB | $0.08/GB |
| Bunny CDN | $0.01/GB | $0.01/GB |
For 38 TB/month:
- CloudFront: ~$3,160
- Bunny CDN: ~$380
Optimizing CDN Bandwidth
- Image optimization: WebP/AVIF reduces image sizes 30-50%
- Compression: Brotli for text assets (15-25% smaller than gzip)
- Cache headers: Maximize cache hit ratio with proper
Cache-Control - Lazy loading: Load images only when visible
- Video: use dedicated video CDN (Mux, Cloudflare Stream) for HLS/DASH
Use Case
Web developers estimating CDN costs for new projects, DevOps engineers planning for traffic spikes, e-commerce teams preparing for seasonal sales events, and infrastructure architects comparing CDN providers for cost optimization.