Drag the sliders to see how many idle browsers a warm pool needs, and how cost per session changes as traffic scales.

Idle browsers per active session fall from about 1.38 at 1 browser per minute to about 0.16 at 600 per minute.
Required idle browsers
5
Active browsers
12
Idle-to-active ratio
1 : 2.5

getting leanerYou keep about 0.39 idle browsers for every active session.

Model: burst factor = 1 + 11.4 / sqrt(rate); idle = rate/60 x cold start x burst; active = rate/60 x 36s average session. Browser counts round up to whole browsers. Illustrative, not a quote.