CDN Bandwidth Calculator
A content delivery network (CDN) distributes your website's assets across edge nodes worldwide, reducing latency and offloading traffic from your origin servers. Estimating monthly CDN bandwidth consumption helps you forecast CDN costs, choose the right pricing plan, and set up spending alerts before bills surprise you. This calculator takes your monthly page views, average page weight, CDN cache hit rate, and cost per GB to estimate total edge bandwidth, origin pull bandwidth, and estimated monthly CDN cost. Results reflect realistic workloads where a mix of cacheable static assets and dynamic content is served.
CDN bandwidth formula
edge_GB = pageviews * page_size_KB / (1024 * 1024)
origin_GB = edge_GB * (1 - hit_rate/100)
monthly_cost = edge_GB * cost_per_GB
cost_per_1k = (monthly_cost / pageviews) * 1000
Reducing CDN bandwidth costs
- Enable Brotli or gzip compression to reduce asset sizes by 60-80%.
- Convert images to WebP or AVIF format to save 25-50% on image bandwidth.
- Set long cache TTLs (1 year) for versioned static assets with cache-busting URLs.
- Use HTTP/2 or HTTP/3 to reduce connection overhead and improve parallel delivery.
- Negotiate committed-use pricing with your CDN provider for predictable usage.
Frequently asked questions
How is CDN bandwidth calculated?
CDN bandwidth = total_requests * average_response_size * (1 - cache_hit_rate). The cache hit rate reduces origin pull traffic; the remaining traffic is served from CDN edge caches. Total bandwidth billed by CDN providers includes all data transferred from edge nodes to end users, regardless of whether it was a cache hit or miss.
What is a typical CDN cache hit rate?
Well-optimized CDN configurations achieve 85-95% cache hit rates for static assets like images, CSS, and JavaScript. Dynamic content and personalized responses typically have lower hit rates. Increasing cache TTL, using cache keys carefully, and avoiding query-string cache busting can improve hit rates.
How do CDN providers charge for bandwidth?
Most CDN providers charge per gigabyte of data transferred from edge servers to end users. Pricing varies by region: North America and Europe are typically cheapest; Asia-Pacific and Latin America cost more. Committed-use pricing (paying upfront for a bandwidth commitment) offers significant discounts over pay-as-you-go rates.
How does image optimization affect CDN bandwidth?
Serving WebP or AVIF images instead of JPEG/PNG reduces file sizes by 25-50%. Responsive images (serving smaller images to mobile devices) can cut mobile bandwidth by 60-80%. These optimizations reduce both CDN costs and page load times, making image optimization one of the highest-ROI CDN configurations.
What is the 95th percentile billing method?
Some CDN providers bill using the 95th percentile of 5-minute bandwidth samples over the billing period. This method discards the top 5% of peak traffic samples, giving you burst capacity without paying for extreme spikes. It is commonly used in transit and wholesale bandwidth agreements.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.