Screen Session Count Calculator

Work out screen session count instantly with clear inputs, formula shown and shareable results.

About Screen Session Count Calculator

Every detached screen or tmux window holds a shell and usually a child process open indefinitely, so abandoned sessions accumulate memory and process slots on shared bastion hosts. A hundred sessions with five windows each is 500 shells and around 1,500 processes doing nothing, which also inflates the task count against pid_max.

Formula

Session footprint

sessions = engineers x sessions each; windows = sessions x windows per session; memory = windows x per-window memory

Worked example

With the default values below, Screen Session Count Calculator returns Detached sessions on the host of 100. Change any input above and every figure here is recalculated in your browser.

Inputs used

Engineers using the hostminimum 1: 25
Detached sessions eachminimum 1: 4
Memory per windowminimum 0.1 MB: 14 MB
Windows per sessionminimum 1: 5

Results

Detached sessions on the host: 100
Total windows: 500
Memory consumed: 6.52 GiB
Processes held open: 1,100

Step by step

1Values used
2Session footprint
3Detached sessions on the host= 100
4Total windows= 500
5Memory consumed= 7,000,000,000
6Processes held open= 1,100

Assumptions and limits

The result is derived only from the 4 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 whole numbers, 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

Should abandoned sessions be reaped?

Yes, on shared hosts. A scheduled job that kills sessions idle beyond a threshold prevents indefinite accumulation, provided users are warned.

Is tmux lighter than screen?

Marginally, and it handles reattachment and pane management better. The dominant cost in both is the shells and their children, not the multiplexer itself.