Size Your Walk-in Refrigeration Unit

When buying refrigeration units for walk-in coolers & freezers, it’s very important that your refrigeration is sized correctly for your box and application. Incorrectly sized refrigeration can result in problems such as the refrigeration unit constantly running and eventually freezing up.

To help you get the right size refrigeration unit, Heatcraft Worldwide Refrigeration has put together a Quick BTUH Load Calculation Chart. It can be used for walk-ins rooms from 6’ X 6’ X 8’ to 40’ X 40’ X 8’ and with holding temperatures of -20°F, -10°, 0°, 30° and 35°. Loads are calculated based on boxes utilizing 4” of urethane R-25 insulation.

heatcraft refrigeration chart
Click here to view the Refrigeration Sizing Chart

Before using these charts, get this information about your walk-in cooler or walk-in freezer:

1. Room information:

•Length, width, and height of the box in feet

•Holding temperature of the refrigerated room (°F)

•Relative humidity in the refrigerated room (if specified)

•Summertime design ambient temperature (°F). This is usually the temperature expected at the location of an air cooled condensing unit which cools the room

2. Insulation information:

•Type of insulation, insulation thickness (inches), and external temperatures on walls, ceiling, and floor.

3. Infiltration load information:

•The temperature (°F) of the entering air and the relative humidity of the entering air. Also, an estimate of the door usage – average, heavy, etc.

•Does the box have glass doors? Dock doors? How many?

4. Product load information:

•What is the product or mix of products being stored?

•How many pounds of product entering at what temperature?

•How long (hours) does it take to load the product into room?

•How quickly (hours) should the room pull the product down to what temperature?

•How many pounds of fruit and vegetables are in the room? (respiration load)

5. Miscellaneous loads information:

•How many people work in the room?

•What is the lighting (watts)?

•How many motors (HP) do work in the room?

Here are some ballpark BTUH requirements for common sizes and holding temperatures. Use the “Heavy Load” calculation for walk-ins with glass doors or ones that have frequent traffic.


35 Degree Cooler with 8ft Height

Dimensions (LxW) BTUH (Typical Load) BTUH (Heavy Load)
6X6 4986 6540
6X8 5884 7470
8X8 6939 8350
8X10 7934 9600
10X10 9072 10790


0 Degree Freezer with 8ft Height

Dimensions (LxW) BTUH (Typical Load) BTUH (Heavy Load)
6X6 4522 6570
6X8 5296 7390
8X8 6193 8360
8X10 7032 9270
10X10 7980 10310

-10 Degree Freezer with 8ft Height

Dimensions (LxW) BTUH (Typical Load) BTUH (Heavy Load)
6X6 4859 7070
6X8 5692 7960
8X8 6654 8990
8X10 7555 9960
10X10 8573 11070

If you’re looking for general refrigeration sizing and BTUH load requirement information for walk-ins, try our Refrigeration Sizing Calculator *

refrigeration sizing program

*All refrigeration sizes are estimates and may not accurately represent specific applications. By using this calculator you are agreeing that in no event, shall U.S. Cooler be liable for special or consequential damages in connection with the use or output of the U.S. Cooler refrigeration sizing software. For detailed sizing and pricing, call U.S. Cooler at 800.521.2665.

  • T.J. O'Connor July 26, 2013 at 9:33 pm

    Looking for a 10’X 12’X 7’6″
    Self Contained
    Top Mounted
    1 1/2 HP Compressor
    No Floor

    Looking to buy ASAP…

  • nurul huda February 16, 2014 at 12:41 am

    Dear sir please can you send to us calculating 14f x 14f x 12f temp -22c total how much BT u/h total KW.

    Thank you & best regard
    Nurul huda
    Al dar al qateriya for contracting
    Doha Qatar
    Tel +974 44397019
    Mobil. +974 55998216

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