Refrigeration BTU Calculator

Refrigeration BTU Calculator [Find the Size of Your Walk-In]

Calculating the right size refrigeration system for a new walk-in cooler or freezer prevents inefficient operation and high energy costs. But most importantly, it keeps food fresh and safe, which keeps your HVAC customers in business.
Use ServiceTitan’s refrigeration BTU calculator to determine your exact needs for a new walk-in cooler or freezer, or to troubleshoot issues with existing refrigeration equipment.

How to Use Our Free Refrigeration BTU Calculator

Use ServiceTitan’s calculator when you need to estimate BTUs for a walk-in cooler. Enter data, including your walk-in cooler or freezer dimensions, temperatures, and performance factors, into the appropriate fields. The refrigeration BTU calculator then uses your entries to estimate the system specifications you need.

Step 1

Enter the height, width, and depth of your walk-in cooler or freezer unit in inches. Enter fractions as decimal equivalents, such as .5 for one-half or .33 for one-third.

Step 2

Add temperature data, including holding temperature (the temperature setting inside the walk-in), ambient temperature (the temperature outside the walk-in), and incoming product temperature. For example, frozen french fries would have a lower incoming temperature than fresh potatoes.  

Step 3

Specify performance factors including insulation, door type, and product load. For instance, a fast food restaurant cooler storing 50 pounds of ground beef and 25 pounds of produce would have a product load of 75 pounds.

After you’ve entered the data from the steps above, hit “Calculate.” The refrigeration BTU calculator will estimate your cooling system requirements.

What is a BTU?

BTU (British Thermal Unit) is a unit of energy. It measures the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. In the context of cooling and air conditioning, BTUs measure the amount of heat a refrigeration system can remove from a space.
For instance, a refrigeration system rated at 10,000 BTU removes 10,000 BTUs of heat from a walk-in space. Sometimes BTU is expressed as BTUH, which means BTUs per hour. In that case, a cooling load of 10,000 BTUH means a refrigeration system can remove 10,000 BTUs of heat each hour.
Window ACs offer a simplified example for understanding of BTUs, where 20 BTU per square foot is typically recommended to cool a room. So, a room size of 300 square feet would need a 6,000 BTU window AC.
Figuring the cooling capacity for an entire house, on the other hand, is more complex. Variables such as occupancy must be factored along with square footage. For that, you’d need the help of an HVAC load calculator and HVAC duct calculator.

Why BTU Load Calculation is Important

Underestimating BTU requirements is as problematic as overestimating them. Too few BTUs results in a walk-in cooler or freezer that can’t remove heat fast enough, leading to spoilage.

Too many BTUs results in energy waste and higher operating costs. It may also prematurely age components such as the compressor, evaporator, and air handler, as well as the outside condensing unit.

For these reasons, it’s important to have a go-to refrigeration BTU calculator you can trust. Doing so ensures you choose the right refrigeration system, leading to a job done on time and on budget.

How Do I Calculate BTU for Refrigeration? [Simplified Version]

If you need to quickly estimate BTUs in the field and don’t have access to an online calculator or HVAC software, use this simplified equation for a quick estimate. It contains only three variables, making it easier to remember.
Volume of air X Specific heat capacity at constant pressure X Difference of temperature

Here’s what these variables mean:

• Volume of air: This is the volume of air you need to cool, typically measured in cubic feet or cubic meters. For instance, if you’re installing a 10-foot-by-10-foot-by-10-foot walk-in at a fast food restaurant, the volume of air would be 1,000 cubic feet.

• Specific heat capacity at constant pressure: The specific heat capacity of standard air — clean, dry air at sea level with a temperature of 70 degrees Fahrenheit — is approximately 0.24 BTU per pound Fahrenheit.

• Temperature difference: This is the difference between the initial and final temperatures of air. If the kitchen keeps the ambient temperature outside the walk-in at 80 degrees Fahrenheit, and the walk-in’s internal temperature setting is 38 degrees, then the temperature difference would be 42 degrees Fahrenheit (80 minus 38).

Now let’s calculate estimated BTUs using the numbers above.

1,000 X 0.24 X 42 = 10,080 BTU

This estimate gives you a strong starting point. You know the walk-in’s refrigeration system will be in the neighborhood of 10,000 BTU. From there, you can refine your estimate back at the office before you prepare a final quote.

Disclaimer Statement

The simplified BTU equation provided here is for informational purposes only. All calculations should be considered estimates that may not accurately represent the specific requirements of installing a new walk-in cooler or freezer. ServiceTitan assumes no liability for any errors or inaccuracies in the calculator results, or for any damages that may result from the use of the calculator.