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Gaming Stream Server Capacity Estimator

The Gaming Stream Server Capacity Estimator calculates the origin-side bandwidth and server count needed for a live gaming stream based on concurrent viewers, average stream bitrate, CDN offload, server egress capacity, and a safety buffer. It is intended for stream operators who want a quick infrastructure estimate before running a load test or selecting a delivery architecture.

The calculator separates total audience bandwidth from origin bandwidth. A higher CDN offload percentage reduces the traffic that must be served directly from origin, while the headroom factor increases the provisioned requirement for spikes and uncertainty. The output is a rounded server count plus supporting bandwidth figures.

Inputs

viewers
Mbps
%
Gbps
%
Result
—
Recommended origin servers
Total audience bandwidth—
Buffered origin bandwidth—
Usable egress per server—

1. Enter concurrent viewers
Use the highest expected simultaneous audience for the stream.

2. Enter average bitrate
Use the delivered average bitrate per viewer in megabits per second.

3. Set CDN offload
Enter the percentage of viewer traffic expected to be delivered without returning to origin.

4. Enter origin-server egress
Use the tested usable network throughput of one origin server, not merely the physical port rating.

5. Add headroom and review
Apply a safety buffer, then review the rounded server count and bandwidth requirements.

Audience bandwidth (Gbps) = Viewers × Bitrate (Mbps) / 1000
Origin bandwidth before buffer = Audience bandwidth × (1 − CDN offload % / 100)
Buffered origin bandwidth = Origin bandwidth × (1 + Headroom % / 100)
Recommended servers = ceil(Buffered origin bandwidth / Usable egress per server)

Where:

  • Viewers = peak simultaneous viewers.
  • Bitrate = average delivered stream bitrate per viewer in Mbps.
  • CDN offload = share of audience traffic handled without origin delivery.
  • Usable egress = tested Gbps capacity per origin server.

Assumptions: The model treats bitrate and offload as averages and only models network egress capacity. Encoding, CPU, memory, storage, protocol overhead, and regional failover may require additional resources.

What the result means

The main result is the number of origin servers needed to carry the buffered origin-side bandwidth under the entered assumptions.

Actual architecture may use redundant origins, multi-region failover, or managed streaming services that change how server count should be interpreted.

Given:

  • 50,000 concurrent viewers
  • 6 Mbps average bitrate
  • 95% CDN offload
  • 8 Gbps usable egress per origin server
  • 25% headroom

Calculation:
Audience bandwidth = 50,000 × 6 / 1000 = 300 Gbps. Origin before buffer = 300 × 0.05 = 15 Gbps. Buffered origin = 15 × 1.25 = 18.75 Gbps. Servers = ceil(18.75/8) = 3.

Result:
3 origin servers.

Interpretation:
The audience consumes about 300 Gbps in aggregate, but strong CDN offload reduces the buffered origin-side requirement to 18.75 Gbps.

Why is total audience bandwidth much larger than origin bandwidth?

With a CDN, most viewer traffic can be served from edge caches or distributed delivery nodes. The origin only handles the fraction not offloaded.

What bitrate should I use for adaptive streaming?

Use a weighted average delivered bitrate across the expected rendition mix, or run separate scenarios for low and high cases.

Should server egress equal the network port speed?

Not automatically. Use a tested sustainable throughput after accounting for protocol overhead, system limits, and your reliability target.

Does this include video encoding servers?

No. This model focuses on outbound delivery bandwidth. Encoding and transcoding capacity should be planned separately.

How should I account for failover?

Headroom can cover some redundancy, but true failover often requires explicit extra servers or regions. Treat the result as the serving requirement before your resilience policy.