Art of Simulation

Do Self Checkouts Reduce Queue Time?

Brian Harrington  /   Aug 18, 2015

Most of us have probably seen “Self Checkout Lanes” at supermarkets and some retail stores such as Ikea, Walmart, and Home Depot.  But do they reduce overall queue time? We use simulation to find out if self checkouts are really improving customer experience by reducing waiting times, or if they are slowing down the whole process.



What we can see from the simulation – available to download below – is that if more customers in a store have a better understanding of how to use the self checkouts then the average queue time decreases. However, in a store that would have a less “savvy” demographic we would see queue times increase dramatically as customers would be more likely to join the manual cashier queues. This simulation can help a store decide if they should invest in more self checkouts or more manual cashier lanes. Why not try it out for yourself?


Recent statistics show that self checkout systems in the retail industry are becoming more and more mainstream. According to a 2014 study –  with a sample of 2800 consumers from around the world – 73-94% of consumers are using self checkout lanes. As you may suspect the 94% range consists of younger people aged 18 to 34 years, with the 65+ group at the 73% end of the scale*.


The survey definitely supports that the majority of us are using this technology largely irrespective of age. Most of us consider using the self checkout lanes in hopes of reducing our waiting time at the manual cashier lanes. Retailers are attempting to gain higher profit margins by increasing customer satisfaction and allowing cashiers to perform additional tasks while customer queues are low. As more and more retailers join the self checkout race their operational teams will be facing several new questions from upper management.


Typical questions from upper management:

  • How many self-checkout terminals should we purchase?
  • Can we reduce the number of cashier registers?
  • How many cashiers do we need per shift?
  • What is the average wait time on a self checkout terminal?
  • What is the average wait time on a cashier checkout?
  • What will the new wait time be at our existing cashier registers?
  • What range of demand will our self checkout terminals support?
  • What is the ROI for purchasing self-checkout terminals?
  • What is the average number of shoppers in store?
  • Can we meet our internal goal of an average of 1.2 customers per line?
  • What is the utilization of cashiers at register?


Queuing Theory & Simulation

Most of these questions fall into the realms of “Queuing Theory”; but they become increasingly complex to solve when we include human perception, which drives acceptance and usage. We might have access to several surveys depicting self-checkout data per multiple demographics such as age, race, sex, etc – but the most effective way to apply queuing theory is in conjunction with a simulation model. All of these customer profiles can be included within the simulation where we can assign a label to the customer as an attribute (“lbl SCO Savvy”). This represents how savvy a particular customer is about using a self-checkout terminal.


All of the above questions can be answered through the below simulation model which is available to download. The simulation captures a typical retailer’s shop floor and checkout process. This store has an average of 133 shoppers at any time, uses 8 cashiers, and has just recently installed 5 self-checkout terminals. The store historically had an average queue line of greater than 2 customers per register; which included a designed (15 items or less) lane.


Simulation leads the way

Do Self Checkouts reduce queue time? In a store where customers know how to use the self checkouts (“SCO Savvy”) we can see that yes, queue time decreases. Try the slider for yourself where if the percentage of “SCO Savvy” consumers drops we will see a much higher average queue time and vice-versa. As we know in real life, different stores have different types of consumers so why don’t you look at your store and see if it has enough/too many self checkouts based on consumer demographic?


At SIMUL8 we have seen several supermarket and grocery store chains such as Kroger successfully use simulation when applying queuing theory to their shop floors. As this technology expands into additional retail segments such as department stores and convenience stores, simulation will likely lead the way!

If you would like to find out how we helped Kroger in a real life situation please get in touch


Want to Try it Out?

Download the simulation and see how you can improve the shopping experience!

Don’t have SIMUL8? Get in touch to request a trial