Evacuation Time Calculator

Work out evacuation time instantly with clear inputs, formula shown and shareable results.

About Evacuation Time Calculator

Evacuation time is the walking time to reach an exit at about 1.2 metres per second, plus the queuing time as occupants pass through the exits at the stated flow rate. Losing one exit does not add a third to the time, it adds half again to the flow component, which is why blocked exits matter so much more than long corridors.

Formulas

Flow time

minutes = occupants / (exits x flow rate per exit)

Travel time

minutes = travel distance / (1.2 m/s x 60)

Worked example

With the default values below, Evacuation Time Calculator returns Estimated evacuation time of 3.52. Change any input above and every figure here is recalculated in your browser.

Inputs used

Number of occupantsminimum 1: 400
Usable exitsminimum 1: 3
Flow rate per exitminimum 1 people/min: 45 people/min
Longest travel distance to an exitminimum 0.1 m: 40 m

Results

Estimated evacuation time: 3.52 min
Time limited by exit capacity: 2.96 min
Time to reach an exit: 0.56 min
People per exit: 133

Step by step

1Values used
2Flow time
3Travel time
4Estimated evacuation time= 3.52 min
5Time limited by exit capacity= 2.96 min
6Time to reach an exit= 0.56 min
7People per exit= 133

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 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
A simplified hydraulic model for orientation only. Real evacuation analysis requires a competent fire engineer.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

A simplified hydraulic model for orientation only. Real evacuation analysis requires a competent fire engineer.

Frequently Asked Questions

How is the Evacuation Time figure worked out?

minutes = occupants / (exits x flow rate per exit). Evacuation time is the walking time to reach an exit at about 1.2 metres per second, plus the queuing time as occupants pass through the exits at the stated flow rate.

Why does this matter?

Losing one exit does not add a third to the time, it adds half again to the flow component, which is why blocked exits matter so much more than long corridors.

What do I need to enter?

Enter number of occupants, usable exits, flow rate per exit, longest travel distance to an exit. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.