01
Formula
Room BTU/h = area × your factor + 600 × extra people.
Box BTU/h = cubic feet × temperature difference × 0.1 × your usage factor. Tons = BTU/h ÷ 12,000. Switch the control to Walk-in for a cooler or a freezer box.
Apply for financingHVAC load
HVAC load calculator for rooms and walk-in coolers
This HVAC load calculator estimates cooling BTU per hour for a room from area and a BTU-per-square-foot factor you set, or for a box from volume and temperature difference. Divide by 12,000 when you want a tonnage calculator. The walk-in mode is the refrigeration load calculator and the walk in cooler calculator. It is a rule of thumb, not a Manual J or an ASHRAE box load.
Space
Room planning load
10,000BTU/h
Tons0.83
Area400 sq ft
People add-on0 BTU/h
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
Tons are BTU per hour divided by 12,000.
Room load equals length times width times your BTU per square foot, plus 600 BTU per hour for each person beyond two. A 20 by 20 foot room at 25 BTU per square foot and no extra people is 10,000 BTU per hour, or 0.83 tons. Walk-in load equals interior cubic feet times the degrees you are holding below the surrounding room times 0.1 times a door-and-product factor. An 8 foot cube pulled down 35 degrees with a 1.5 factor is 8 times 8 times 8 times 35 times 0.1 times 1.5, which is 2,688 BTU per hour, or 0.22 tons. The 0.1 and the 25 are planning factors you can change. They are not a substitute for a load calculation on a set of plans. Insulation, glass, and ventilation are why a real load moves.
02
Example
A 20 by 20 room at 25 BTU per square foot.
The room result is 10,000 BTU per hour and 0.83 tons. Switch to Walk-in with the 8 foot cube, 35 degrees, and a 1.5 factor and the refrigeration load is 2,688 BTU per hour. That walk in cooler calculator result is a planning load, not equipment selection by itself.
03
Tips
Pick the factor for the climate you actually have.
Twenty-five BTU per square foot is a moderate planning default, not a code value. A kitchen, a west glass wall, or a hot climate needs a higher factor. A walk-in that is opened all day needs a higher usage factor than a box that stays shut.
04
Equipment
The condenser and the evaporator are the purchase.
Dengaro arranges financing for HVAC equipment. The BTU figure is not sent as a loan amount. A contractor still sizes the machine.
Important questions
Know what to expect.
Is this a Manual J?+
No. Manual J counts windows, insulation, and direction. This HVAC load calculator is a square-foot or a volume shortcut so you can see the scale of the load.
How do I read the tonnage calculator line?+
Divide BTU per hour by 12,000. A 12,000 BTU per hour load is one ton. The page does that division for you.
What does the walk in cooler calculator ignore?+
Product pull-down, door swings beyond the factor you typed, and the condenser rating at the design outdoor temperature. Use the result to start a conversation with the refrigeration supplier.
Are the factors quotes?+
No. They are inputs. Change them when you have a better planning number. Dengaro arranges equipment financing. The factors are inputs, not a quoted capacity.
Financing built into the sale