CDN Bandwidth Calculator
Size CDN and origin bandwidth from visitors, page weight and a peak-to-average ratio instead of a monthly average.
Inputs
The HTTP Archive median desktop page is around 2.5 MB.
Consumer traffic typically peaks 3–6× its monthly average during prime time.
Peak Edge Bandwidth
0.160Gbps
Average Edge Bandwidth
40.00Mbps
Peak Origin Bandwidth
0.019Gbps
Monthly Traffic Delivered
12.96TB
Monthly Volume in Bytes
12 TiB
Peak Requests per Second
375
Step by step
Values used
Monthly visitors = 1,200,000 visitors; Page views per visit = 4.50 views; Average page weight = 2.40 MB; HTTP requests per page view = 45 requests; Edge cache hit ratio = 88 %; Peak-to-average ratio = 4 ×
CDN Bandwidth
average Mbps = total bytes × 8 ÷ seconds in the month; peak Gbps = average × peak-to-average ratio ÷ 1,000; origin peak = peak × (1 − cache hit ratio).
Peak Edge Bandwidth
= 0.160 Gbps
Average Edge Bandwidth
= 40.00 Mbps
Peak Origin Bandwidth
= 0.019 Gbps
Monthly Traffic Delivered
= 12.96 TB
Monthly Volume in Bytes
= 12,960,000,000,000
Peak Requests per Second
= 375
How it works
A monthly average hides the busy hour, so the average bit rate is multiplied by a peak-to-average ratio to get the figure your links and origin must actually survive. Only the miss fraction reaches the origin, which is why a high cache hit ratio shrinks origin bandwidth far faster than it shrinks CDN volume. CDN contracts and origin egress are sold on peak Mbps or committed volume, and origin capacity has to be built for the peak miss rate — sizing on the average is how a launch saturates the origin uplink while the CDN reports plenty of headroom.
Formula
CDN Bandwidth
average Mbps = total bytes × 8 ÷ seconds in the month; peak Gbps = average × peak-to-average ratio ÷ 1,000; origin peak = peak × (1 − cache hit ratio).
- peak-to-average ratio
- How much busier the busy hour is than the monthly mean
- total bytes
- visitors × page views × page weight
- origin peak
- The share of the peak the cache cannot absorb
Frequently Asked Questions
How is CDN Bandwidth calculated?
average Mbps = total bytes × 8 ÷ seconds in the month; peak Gbps = average × peak-to-average ratio ÷ 1,000; origin peak = peak × (1 − cache hit ratio). A monthly average hides the busy hour, so the average bit rate is multiplied by a peak-to-average ratio to get the figure your links and origin must actually survive. Only the miss fraction reaches the origin, which is why a high cache hit ratio shrinks origin bandwidth far faster than it shrinks CDN volume.
Why does CDN Bandwidth matter?
CDN contracts and origin egress are sold on peak Mbps or committed volume, and origin capacity has to be built for the peak miss rate — sizing on the average is how a launch saturates the origin uplink while the CDN reports plenty of headroom.
What values do I need to enter?
This calculator takes 6 inputs: Monthly visitors, Page views per visit, Average page weight, HTTP requests per page view, Edge cache hit ratio, Peak-to-average ratio. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.