HVAC Load Calculator
Cooling load in BTU and tons.
Enter your values
Enter the floor area in ft².
Enter the base load factor in BTU/ft².
Enter the occupants you are working with.
Enter the sun-facing windows you are working with.
Enter the equipment load in W.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Cooling load
- 48,918 BTU/h
- Tons of cooling
- 4.08
- Kilowatts
- 14.34
- Recommended unit
- 4.5 ton
Quick answer
Cooling load combines building fabric gains with heat from people, lights and equipment.
BTU/h = area × factor + people × 600 + equipment
At a glance
| What it does | Cooling load in BTU and tons. |
|---|---|
| Category | Engineering |
| Inputs needed | Floor area, Base load factor, Occupants, Sun-facing windows, Equipment load |
| Main output | Cooling load |
| Formula | BTU/h = area × factor + people × 600 + equipment |
| Cost | Free — no sign-up, no download |
How to use the HVAC Load Calculator
- 1Enter the conditioned floor area.
- 2Adjust the load factor for your climate and insulation.
- 3Add occupants, glazing and equipment.
Inputs explained
- Floor area(ft²)
- Enter the floor area in ft².
- Base load factor(BTU/ft²)
- Enter the base load factor in BTU/ft².
- Occupants
- Enter the occupants you are working with.
- Sun-facing windows
- Enter the sun-facing windows you are working with.
- Equipment load(W)
- Enter the equipment load in W.
Worked example
Using the values the calculator loads with:
Inputs
- Floor area1600 ft²
- Base load factor22 BTU/ft²
- Occupants6
- Sun-facing windows5
- Equipment load1500 W
Results
- Cooling load48,918 BTU/h
- Tons of cooling4.08
- Kilowatts14.34
- Recommended unit4.5 ton
Frequently asked questions
Is bigger always better?
No — oversized units short-cycle and fail to dehumidify.
Is this a Manual J?
No, it is a screening estimate; specify from a full Manual J load.
What do I need to enter into the HVAC Load Calculator?
Just 5 values: floor area, base load factor, occupants, sun-facing windows, equipment load. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the HVAC Load Calculator work out the answer?
Cooling load combines building fabric gains with heat from people, lights and equipment. It applies the formula BTU/h = area × factor + people × 600 + equipment and shows the working so you can check each step by hand.
Is the HVAC Load Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.