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WebSocket Connection Calculator

Size servers for concurrent WebSocket connections and message throughput.

About WebSocket Connection Calculator

WebSocket capacity is usually memory-bound rather than CPU-bound, because idle connections consume buffers continuously. File descriptor limits and ephemeral port ranges often bind before memory does. Persistent connections make deployments harder, since every restart forces every client to reconnect at once, which is a thundering herd the system must absorb.

Formula

WebSocket Connection

Memory = connections × per-connection memory; bandwidth = message rate × size × 8

per-connection memory
Socket buffers and application state, typically 20 to 60 KB
connections per server
Bounded by memory, file descriptors and ephemeral ports

Worked example

With the default values below, WebSocket Connection Calculator returns Servers Required of 3. Change any input above and every figure here is recalculated in your browser.

Inputs used

Concurrent connectionsminimum 0
50,000
Memory per connectionminimum 0.1 KB
40 KB
Messages per connection per minuteminimum 0
6
Average message sizeminimum 0 bytes
250 bytes
Connections per serverminimum 1
20,000

Results

Servers Required
3
Total Connection Memory
1.907 GB
Messages per Second
5,000.0
Bandwidth Required
10.000 Mbps
Memory per Server
0.636 GB

Step by step

  1. 1Values used
  2. 2WebSocket Connection
  3. 3Servers Required= 3
  4. 4Total Connection Memory= 1.907 GB
  5. 5Messages per Second= 5,000.0
  6. 6Bandwidth Required= 10.000 Mbps
  7. 7Memory per Server= 0.636 GB

Assumptions and limits

  • The result is derived only from the 5 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 WebSocket Connection calculated?

Memory = connections × per-connection memory; bandwidth = message rate × size × 8 WebSocket capacity is usually memory-bound rather than CPU-bound, because idle connections consume buffers continuously. File descriptor limits and ephemeral port ranges often bind before memory does.

Why does WebSocket Connection matter?

Persistent connections make deployments harder, since every restart forces every client to reconnect at once, which is a thundering herd the system must absorb.

What values do I need to enter?

This calculator takes 5 inputs: Concurrent connections, Memory per connection, Messages per connection per minute, Average message size, Connections per server. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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WebSocket Connection Calculator – Calculate Servers Required