Know the wait before you set the schedule.

Enter arrivals, staff and service times. This free queue simulator runs every customer through your day, so you see the wait and the line hour by hour, and how many staff it takes to keep them short. No sign-up.

Model
Coffee Shop
Open 6am-6pm. Morning rush peaks at 120/hr, slows in the afternoon. 6 baristas 8am-1pm, 4 rest of day.
Inputs · edit any value
Arrivals
Service
Inter-arrival time
Service time
⚙ Distribution
Outputs
Wait (min)
Queue Length
Utilization
Avg
--
--
--
Peak
--
--
--
Max
--
--
--
Calculating...
▶
Schedule & Simulation Settings
Go further

More ways to work the problem

The simulator answers one line at a time. These go deeper on the ideas, try other kinds of systems, or put the engine inside your AI chat.

Why lines form, why averages lie

Utilization, Little's Law and M/M/c in plain English, each tied to a staffing call you have to make.

Read the queueing guide

More systems, ready to run

Barbershops, inventory, dispatch, machine breakdowns and more. Each one runs on the same simulation engine.

Browse the simulation models

Use it inside Claude

Add QueueSim to Claude, Cursor or any MCP app. Ask a staffing question and the answer comes from a real simulation run. Free, no API key.

Add QueueSim to Claude
Stay connected

Join our list

Occasional product updates, new models and case studies.

Beyond the free tool

Your real line has more going on

Customers give up and leave. Some get served first. Staff take breaks, calls get transferred, and work moves through several stations. ChiAha builds custom simulation models for operations like that, on the same engine that runs QueueSim.

Staffing a clinic? QSimHealth is built for that, with labor cost included.