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Virtual Users Required Calculator

Work out virtual users required instantly with clear inputs, formula shown and shareable results.

About Virtual Users Required Calculator

Concurrency follows Little's law again: peak-hour sessions multiplied by the fraction of an hour each session lasts. Daily active users on their own say nothing about concurrency, because a seven-minute session occupies only a ninth of an hour. Adding a 30 percent margin covers the fact that peak-hour concentration is itself an estimate.

Formula

Peak concurrency

daily sessions = DAU x sessions per user; peak-hour sessions = daily x peak share; concurrent = peak-hour sessions x session minutes / 60

Worked example

With the default values below, Virtual Users Required Calculator returns Peak concurrent users of 3,780. Change any input above and every figure here is recalculated in your browser.

Inputs used

Daily active usersminimum 1
120,000
Sessions per user per dayminimum 0.01
1.8
Average session lengthminimum 0.1 min
7 min
Share of daily traffic in the peak houraccepts 0.1–100 %
15 %

Results

Peak concurrent users
3,780
Sessions in the peak hour
32,400
Sessions per day
216,000
Virtual users to configure (30% margin)
4,914

Step by step

  1. 1Values used
  2. 2Peak concurrency
  3. 3Peak concurrent users= 3,780
  4. 4Sessions in the peak hour= 32,400
  5. 5Sessions per day= 216,000
  6. 6Virtual users to configure (30% margin)= 4,914

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

What peak-hour share is typical?

Consumer services often see 10 to 20 percent of daily traffic in the busiest hour; internal tools can exceed 25 percent because usage is confined to office hours.

Should the load test ramp or start at peak?

Both, as separate tests. Ramping finds the breaking point; starting at peak tests cold-start behaviour, which is what a failover actually looks like.

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