Disinfecting Cost

How to Calculate Your Disinfecting Cost

In Disinfecting, Environment by Bob Vitale

As the economy begins to reopen, talk of the “new normal” is everywhere. And for many businesses, that includes new, regular cleaning and disinfecting programs to ensure the safety of employees, customers and visitors. That means adding disinfecting cost to your bottom line.

Planning for this can be a challenge, especially if you’ve never done it before. This post provides a brief guide to help you calculate your disinfecting cost. It will present some ideas to hopefully get you thinking in a proactive way about how to tackle the challenges at your specific location while keeping cost to a minimum. 

This information provided is especially ideal for professional offices, warehouse/distribution centers, retail establishments, educational institutions, long-term care facilities, transit authorities and casinos. With such a broad range, even if you are outside of these industries, chances are you will still find ideas you can apply when planning your own disinfecting program. 

The Basics to Calculate Disinfecting Cost: Where, What and How Often to Disinfect

In a previous post on building disinfection, we discussed how to decide where you need to disinfect. For example, for outside areas or an indoor space that has had no occupancy for seven days, regular cleaning is enough. 

But now, we’ll go a bit deeper exploring what exactly you need to be disinfecting regularly, and what may not be as necessary. The first principle to keep in mind when planning your disinfecting program is “high touch, high traffic.” 

What areas receive the most contact with people in your facility? The basics, of course, are door handles, desks and tables, light switches, toilets and sinks. In a casino, game consoles would be right up there. In a manufacturing environment, equipment, especially access doors, handles and maintenance tools, would also be high touch. Lockers in gyms, schools and manufacturing facilities can be included. Tables, chairs and kitchen appliances in cafeterias and breakrooms in schools, manufacturing plants and long-term care facilities as well. Finally, in warehousing/distribution centers and many retail environments, you can include front-facing shelving, signage and, in the latter, cash registers. 

Especially for larger retail, manufacturing and warehouse facilities, pay attention to the highest amount of foot traffic. If 90% of movement happens around 30% of your building, focus your disinfecting efforts there. Other areas can be disinfected more periodically. This saves on disinfecting cost.

When planning your disinfecting protocol, treat hard surfaces as a higher priority than soft. Virus particles stay on hard, nonporous surfaces (e.g., glass, vinyl, stainless steel, plastic) on average twice as long as soft, porous surfaces (like carpet, upholstery and other fabrics).[1]

The last two points bring us to flooring. Carpeted floors and upholstery in casinos, offices, schools and hotels benefit from a regular cleaning schedule. If you are going to occasionally disinfect, focus on high traffic areas and choose a disinfectant product from the EPA’s List N that is suitable for porous material. For hard floors, once again, prioritize areas with significant foot traffic, like bathrooms, cafeterias and school hallways. Based on the amount of foot traffic, you can decide whether you feel like weekly disinfecting would be enough. 

For high touch surfaces, make sure you disinfect at least daily. In some places, you might want to plan for more frequent disinfecting. For example, cafeteria tables in schools and larger manufacturing plants, bathrooms in high traffic areas, game consoles in casinos, front-facing shelves in retail environments and touch points in public transit vehicles are all touched many times by many different people. So aim for twice a day (or even more). For other places where contact is usually from the same person throughout the day, like lockers and office desks, once a day seems to be the consensus.[2]

With these things in mind, we’ll show how you can calculate how much disinfectant to order. This will help you determine your disinfecting cost:

  1. Total square footage to disinfect
  2. Dilution rate of the concentrate to make solution
  3. Application rate/coverage (how many square feet one gallon of solution disinfects)
  4. Frequency of application

We also have a bonus at the end: an actual commercial disinfectant calculator to help you with the math.

1.    Calculate the Total Square Footage to Disinfect

Now that you’ve narrowed down what needs to be a regular part of your disinfecting program, it’s time to actually determine how much square footage to disinfect. 

Of course, this is going to be different based on your type of facility, traffic, specific ratio of surface areas that require disinfectant to square footage, etc. But here’s a few starting points to get you heading in the right direction.

Begin with the number of square feet your facility covers. If you plan on disinfecting your entire floor space weekly, you can use this number separately to plan a more periodic disinfecting program. But regardless of whether you will disinfect floors, you can still use this number to get a rough idea of the amount of surface area you’ll need to cover. 

Here are some common examples: 

  • Casinos: the average casino is 97,000 square feet
  • Schools: average school is 118,500 square feet, while the average daycare is 8,000 square feet
  • Long-term care facilities: 124,000 gross square feet, with 69,000 of that rentable space[3]
  • Retail establishments: ranges from boutiques (under 1,000 square feet) to major retail brands (1,000 to 50,000 square feet) to anchor stores (up to 100,000 square feet); Costco, the largest, averages nearly 150,000 square feet per store
  • Office spaces: the average for a small office is 150 square feet per person; add on half to two-thirds of that amount per person for various communal spaces
  • Warehouse/distribution centers: the average is 375,000 square feet
  • Manufacturing plants: ranges from 250 to 1,400 square feet per person, depending on the industry[4]
  • Public transit: using the Chicago Transit Authority as an example, the average across all city buses is 1,600 square feet (surface area of walls, ceilings and floors) and passenger train cars is 2,200 square feet; all public spaces, bathrooms, congested work spaces and locker rooms in the city add up to 12.2 million square feet 

Some of these spaces — such as bathrooms, locker rooms and city transit vehicles — will probably need a 100% coverage disinfecting regimen. In that case, on top of the square footage, you need to know the surface area of the walls. Simply take the length of the room by the height, and double it to account for both long walls, then take the width by the height and double that, which will give you both of the short walls. Add all of that the square footage of the floor and you have your number for that space.

Other spaces can be a bit trickier. For the sake of simplicity, you could choose to experiment. For facilities with a significant amount of hard spaces, like schools (with non-porous floors and lockers), just use the square footage of the floor as an estimate for the area of all surfaces that need covered in your disinfecting program. For facilities with a lot of soft surfaces (e.g., office chairs, carpeted floors), you might try one-third to one-half of the square footage of your building. Once you dial that in, you’ll have something consistent to work with going forward.

Remember – you’re always better off overshooting by a few hundred square feet. You can calculate how much is left and determine exactly what you used, and therefore will need for the next time. So when in doubt, round up. 

2.    The Dilution Rate Also Impacts Your Disinfecting Cost

So now you have a rough figure to work with — the amount calculated to figure out your disinfecting cost. 

The next thing to understand is that you want to measure your disinfectant product cost by the diluted solution, not the concentrated product. For example, if a product label says to dilute one part concentrate into 100 parts water, that means one gallon of concentrate becomes 100 gallons of diluted solution. Now you have 100 gallons to work with, so the cost of that one gallon of concentrate is spread out over 100 gallons of diluted solution. 

Knowing that, we can estimate some costs of common disinfectant products you could just pick up in the store. 

A gallon of standard retail disinfectant can be diluted at a rate of 64:1; in other words, one gallon of concentrated disinfectant makes 64 gallons of diluted solution. The cost for one gallon is about $16.80. This means you are paying $16.80 for 64 gallons of solution. 

Alternatively, we can use the CDC’s alternative recommendation, if EPA-approved disinfectants aren’t available: household bleach. 

Bleach can be diluted at a rate of 48:1. The cost per gallon of bleach is around $2.67. This works out to $2.67 for 48 gallons of solution. 

3.    Don’t Forget the Application Rate/Coverage

To get an accurate idea of how much your disinfectant program will cost, however, we need to determine how much square footage a gallon of solution will cover. This is sometimes a little harder to find before ordering a product. Product descriptions and the label on the product should provide this. Typical retail disinfectants and bleach cover somewhere between 150-250 square feet per gallon. Others will cover up to 15,000 square feet. That makes a major difference in your overall disinfecting cost. However, hang with us for one more important consideration. We’ve almost explained all the math.

4.    Frequency: How Often Do You Need to Disinfect?

The last thing to calculate is the number of applications per year you will use. A high school, for example, is used for about 180 days per year. If you disinfect high-touch areas twice per day, then your figure is 360 applications. 

Of course, these numbers vary so much with your individual circumstances, that your best bet is estimate high and have some left over. You can always adjust on your next order but be careful about being stuck without disinfectant. Many companies are finding it hard to keep up with demand and don’t have commercial disinfectant in stock. 

Walking Through the Above Math

With our four numbers in hand (total square footage, dilution rate, application rate and disinfecting frequency), we can begin to figure out how many gallons of solution we’ll need (and thereby, the amount of concentrate to order): 

  • For spaces with a lot of hard surfaces, such as schools, we assume that the entire amount of surface area that needs to be disinfected daily approximately equals the square footage of the building. So, an 80,000 square foot building would need 80,000 square feet disinfected. But wait, there’s more… 
  • For walls and floors that only need disinfected once a week, we take the square footage of the building times 2.5 (an approximate constant used to estimate the surface area of all walls and floors combined). We then divided this by five to get a daily estimated amount. So the daily amount to be disinfected is half of the total square footage. The 80,000 square foot building, for example, would result in 40,000 square feet of walls/floors to be disinfected daily. 
  • So our 80,000 square foot building example would have 120,000 square feet of space that needs to be disinfected. That means the surface factor is 1.5 (80,000 times 1.5 equals 120,000 to be cleaned daily).
  • We have to clean twice daily, so our total square footage to be disinfected per day is 240,000.
  • With an application rate of 250 square feet per gallon of solution, that’s 960 gallons of solution per day.
  • 960 gallons of solution with a dilution rate of 64:1 (retail disinfectant) equals 15 gallons of concentrate.
  • At $16.80 per gallon, that’s $252 per day, or for bleach, $53.40 per day (20 gallons of concentrate based on a 48:1 dilution rate).

The Midwest Disinfecting System: The Most Affordable Disinfectant on the Market

At Midwest, we’re problem solvers. So we tackled the challenge of creating a system that is the most cost-effective on the market, completely safe (no toxic residues left, like you have with other disinfectants like bleach) and does the job better. 

Midwest’s Disinfecting System uses Proxitane AHC, a blend of hydrogen peroxide and peracetic acid. It is diluted one part to 320 parts water and contains a detergent, eliminating the need to pre-clean surfaces. After application, it only leaves water, oxygen and vinegar behind. It’s completely safe for people and the environment!

One gallon costs $90, but based on the dilution rate, it makes 320 gallons of solution. This breaks down to an application cost of only $0.28 per gallon applied.

And here’s what really makes a difference compared to other disinfectant costs: one diluted gallon of Proxitane AHC covers 15,000 square feet. The one gallon of diluted bleach or retail disinfectant solution we discussed earlier only covers 250 square feet (maximum). That means you’d need 60 gallons of bleach to match one diluted gallon of Proxitane AHC.

To help visualize the price difference, here’s the disinfecting cost of 15,000 square feet, by product: 

  • Bleach ($0.06/gallon of solution): $3.36
  • Retail disinfectant ($0.26/gallon of solution): $15.75
  • Midwest’s Proxitane AHC ($0.28/gallon of solution): $0.28

Using the school example above, $252/day for retail disinfectant for this school means $45,360 for one school year. Using bleach instead, it means $9,612 per year. With Midwest’s Disinfecting System, it means only 9 total gallons of concentrate. That’s only $810 for the entire school year! Plus imagine the labor savings of transporting only 9 gallons of concentrate versus 2,700 gallons of retail disinfectant concentrate.

If word problems are not your thing, we promised … a calculator! To help you get a rough estimate for your own facility, check out our free calculator here. You can plug in your square footage, how often you plan on disinfecting every day and how many days per year the facility is used. Based on our surface factor of 1.5, you’ll see your cost per 15,000 square feet of surface covered as well as your total disinfecting cost per year. Different product options are included, so you can compare costs. 

As with so many Midwest products, the truth is that using the most advanced, effective solutions on the market can actually save you money. To learn more about how to budget for your disinfecting cost, and how Midwest can help you save, check out the Midwest Disinfecting System

[1] On metal, glass and ceramics, it can last up to 5 days. Stainless steel and plastics: 2-3 days. Wood: 4 days. Most other nonporous surfaces: from a few hours up to a single day. 

[2] Daily rate advised by Dr. Alexis Mieses, assistant professor, Department of Family Medicine, UNC School of Medicine.

[3] Based on 122 facilities built between 2017-2018. On average, long-term care facilities have 109 beds, with 79% of those occupied, for an average of 87 residents

[4] Ronderos, L. N. “Stabilization of the U.S. Manufacturing Sector and Its Impact on Industrial Space.” NAIOP Research Foundation, 2013, pg. 7. 

Bob is founder and CEO of Midwest Industrial Supply.