Concurrent Session Capacity Calculator

Work out concurrent session capacity instantly with clear inputs, formula shown and shareable results.

About Concurrent Session Capacity Calculator

Session demand is users multiplied by concurrent sessions each, and per-user counts are far higher than intuition suggests: a modern browser opens dozens of parallel connections per page and background apps hold persistent sockets. Sixty per user is a realistic planning figure, and exceeding the device limit produces intermittent connection failures rather than a clean error.

Formula

Session demand

demand = users x sessions per user; required = demand x (1 + growth allowance)

Worked example

With the default values below, Concurrent Session Capacity Calculator returns Concurrent sessions required including growth of 234,000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Users behind the deviceminimum 1: 3,000
Concurrent sessions per userminimum 1: 60
Device session limitminimum 1: 250,000
Growth allowanceaccepts 0–200 %: 30 %

Results

Concurrent sessions required including growth: 234,000
Current session demand: 180,000
Share of the device limit used: 93.6%
Assessment: Above 70 percent of the limit - plan an upgrade

Step by step

1Values used
2Session demand
3Concurrent sessions required including growth= 234,000
4Current session demand= 180,000
5Share of the device limit used= 93.6
6Assessment= Above 70 percent of the limit - plan an upgrade

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 1 decimal place, 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

Why so many sessions per user?

Browsers open six or more connections per origin and a page loads assets from many origins. Add messaging, email sync, cloud storage and telemetry and 50 to 100 is normal.

Is the session limit or the throughput limit reached first?

Usually sessions, for user-facing traffic. Many small sessions exhaust state long before they saturate bandwidth, which is why both figures must be checked.