CDN Bandwidth Calculator
Size CDN and origin bandwidth from visitors, page weight and a peak-to-average ratio instead of a monthly average.
About CDN Bandwidth Calculator
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
Worked example
With the default values below, CDN Bandwidth Calculator returns Peak Edge Bandwidth of 0.160. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Monthly visitorsaccepts 0–1,000,000,000 visitors
- 1,200,000 visitors
- Page views per visitaccepts 0.1–200 views
- 4.5 views
- Average page weightaccepts 0.01–200 MB
- 2.4 MB
- HTTP requests per page viewaccepts 1–1,000 requests
- 45 requests
- Edge cache hit ratioaccepts 0–100 %
- 88 %
- Peak-to-average ratioaccepts 1–20 ×
- 4 ×
Results
- 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 TiB
- Peak Requests per Second
- 375
Step by step
- 1Values used
- 2CDN Bandwidth
- 3Peak Edge Bandwidth= 0.160 Gbps
- 4Average Edge Bandwidth= 40.00 Mbps
- 5Peak Origin Bandwidth= 0.019 Gbps
- 6Monthly Traffic Delivered= 12.96 TB
- 7Monthly Volume in Bytes= 12,960,000,000,000
- 8Peak Requests per Second= 375
Assumptions and limits
- The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
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.