Restaurant dishwasher rack throughput calculator

Calculate FCFS completion schedule and mean queue wait with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use FCFS completion schedule and mean queue wait to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Arrival times (minutes)
0,1,2
Measured service durations (minutes)
3,3,3
Parallel service stations (count)
1
FCFS completion schedule (JSON)
[{"item":1,"server":1,"start":0,"end":3,"wait":0,"abandoned":false},{"item":2,"server":1,"start":3,"end":6,"wait":2,"abandoned":false},{"item":3,"server":1,"start":6,"end":9,"wait":4,"abandoned":false}]
Mean queue wait (minutes)
2
Last completion (minute)
9

Try another scenario

Arrival times (minutes)
0,0,1
Measured service durations (minutes)
2,2,4
Parallel service stations (count)
2
FCFS completion schedule (JSON)
[{"item":1,"server":1,"start":0,"end":2,"wait":0,"abandoned":false},{"item":2,"server":2,"start":0,"end":2,"wait":0,"abandoned":false},{"item":3,"server":1,"start":2,"end":6,"wait":1,"abandoned":false}]
Mean queue wait (minutes)
0.333333
Last completion (minute)
6
Calculation method

Calculation method

FCFS completion schedule (JSON)

Stable arrival order, earliest-free station, station-number tie break; start=max(arrival,station free).

Mean queue wait (minutes)

Mean start−arrival across all records.

Last completion (minute)

Maximum completion minute.

Symbols and units
a
Arrival times (minutes)
b
Measured service durations (minutes)
c
Parallel service stations (count)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • Each arrival is one dishwasher rack and supplied service duration includes loading, cycle and unloading; identical dishwashers. Supported limits: All numeric inputs and computed intermediates must remain finite. Supported numeric input magnitude is zero or 1e-12 through 1e12 in absolute value; reject values outside this bounded range. All lists/JSON record tables are limited to 100 records unless a stricter bound is stated; reject malformed record arity and wrong member types. Equal nonempty arrival/service lists with <=100 records; arrival>=0, service>0, station count 1..20. FCFS identical stations, no balking, no interruptions.
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