What's This ”Car Per Hour” Thing? - Professional Carwashing & Detailing

What’s This ”Car Per Hour” Thing?

Oftentimes we use terms in the car wash industry that have different meanings and can be confusing to people.


Oftentimes we use terms in the car wash industry that have different meanings and can be confusing to people. I recommend you get a copy of CarWashCollege Glossary of Terms (available on the CWC – Glossary of Terms and PC&D – CWC Glossary of Terms websites) to help you gain a better understanding of common car wash terms. A term that is often used in the industry that confuses both new, and existing, operators is Cars Per Hour (CPH) or Chain Speed.

So what does CPH mean? The textbook definition —

Chain Speed Formula: Inches of roller travel in 15 sec. = cars per hour.

This is where I think people get confused. They think if they are running the chain at a certain speed, let’s say 110 CPH, that they should be washing 110 cars in a hour. Let’s take a look at the math, using that example, and see how it works out.

Average Car Length = 16’ or 192” Roller Travel = 110”/15 sec = 7.3” per sec.
Roller Spacing = 3’ 6” or 42” Seconds Per Hour = 3600
Chain Speed = 110 CPH
Conveyor Length = 110’
Rollers Per Car = 2

So if the average car is 16′ and we have 3’6″ between cars, that would put the space required per car at 234″. It would take the car 32.05 seconds to load, and at that rate you could load 112 cars in an hour.

192” + 42” = 234” 234”/7.3” = 32.05” 3600/32.05” = 112 Output

Using the same formula let’s assume you prep cars at your location and it takes 10 seconds per car.

192” + 42” = 234” 10 second prep time 10 x 7.3” = 73”
307”/7.3” = 42.05” 3600/42.05 = 85 Output

In order to wash 112 cars in an hour while prepping, you would have to run the conveyor at 160 CPH.

160”/15 sec = 10.6” per sec. 192” + 42″ + 106” = 34″
340”/10.6” = 32.07” 3600/32.07 = 112 Output

Let’s use the same formula but instead assume three rollers per car.

192” + 84” = 276” 276”/7.3” = 37.8” 37.8”/3600 = 95.2 Output

Now in order to maximize wash volume and hit the example numbers used you need highly motivated and trained employees. You also need to have specific equipment in place such as an auto roller-up, which can cut seconds off the loading of each car.

By eliminating car prepping, the conveyor could be slowed down by 48 CPH. That slow down would allow the wash equipment and chemicals to thoroughly clean the car with no labor. Your drying capabilities would also increase by approximately 30%. Slowing down the wash would also reduce unnecessary wear on the equipment that occurs by running a conveyor at such a high speed for the output.

The next time you look at making a change to your conveyor speed, remember this information and look at how it will affect your volume. Training your employees to load cars the right way will enable you to make a huge difference in your annual revenue.

Robert Andre is the President of CarWash College™. Robert can be reached at [email protected]. For more information about CarWash College™ certification programs, visit www.CarWashCollege.com or call the registrar’s office at 1-866-492-7422.

You May Also Like

2022 Top 50 U.S. Conveyor Chain List

A snapshot of the leading tunnel brands and operators in the U.S.

Sponsored by:

Each year, the editors of this publication compile and publish a list of the leading conveyorized carwash operators, ranked by number of conveyor locations. Below, you will find the 2022 Top 50 U.S. Conveyor Chain List and some insights into the trends and market shifts that are impacting the industry’s leading chains. 

Featured profile: Cheetah Clean Holding Company

Historical success paired with modern innovation accelerate this wash’s growth.

Top 50 report: Looking back and forward

Reflecting on the carwash market and predictions for its future.

2022 Top 50 Conveyor Carwash List preview

Our list continues to take shape.

Featured profile: Gleam Car Wash

A shining example of investing in the community.

Other Posts

Featured Profile: LUV Car Wash

This carwash chain has a lot of love to give.

LUV Car Wash
Top 50 Conveyor Carwash List prep is underway

The research to validate the information and compile the 2022 list has commenced.

Featured profile: All American Car Wash

Private equity helps keep this 25-year-old wash thriving.

Featured profile: Big League Car Wash

This carwash is headed for the majors.