The Gas Supply BTU Load Calculator helps kitchen designers, mechanical engineers, and restaurant operators determine the minimum pipe diameter needed for natural gas delivery. By calculating the total BTU/hr demand of all gas-fired appliances and accounting for pipe run length and diversity factors, this tool ensures adequate gas pressure at every appliance and compliance with fuel gas codes.

How It Works

Calculation Formula:

Design Demand (BTU/hr) = Total Connected BTU/hr × Diversity Factor (%)

Step 1: Sum Connected Loads
Add up (BTU/hr rating × quantity) for every gas-powered appliance in your kitchen.

Step 2: Apply Diversity Factor
Since not all appliances operate simultaneously, a diversity factor of 70% is commonly used (providing a 30% safety margin).

Step 3: Determine Pipe Diameter
Using NFPA 54 / International Fuel Gas Code tables for low-pressure natural gas (0.5 in. w.c. pressure drop, 0.6 specific gravity):

Pipe DiameterMax Capacity at 100ftMax Capacity at 200ft
1/2″150,000 BTU/hr—
3/4″300,000 BTU/hr200,000 BTU/hr
1″600,000 BTU/hr450,000 BTU/hr
1-1/4″1,000,000 BTU/hr750,000 BTU/hr
1-1/2″1,500,000 BTU/hr1,100,000 BTU/hr
2″3,000,000 BTU/hr2,200,000 BTU/hr
ApplianceTypical BTU/hr
Commercial Range (6-Burner)150,000
Deep Fryer120,000
Broiler80,000 – 120,000
Griddle60,000 – 100,000
Convection Oven60,000 – 100,000
Steamer60,000 – 80,000
Hot Water Heater50,000 – 200,000

FAQ

Q: Why is the diversity factor important in gas sizing?
A: The diversity factor reflects that not all gas appliances run at the same time. Using 70% is standard practice for commercial kitchens to avoid oversizing the pipe.

Q: Can this calculator be used for propane systems?
A: No, this calculator is designed for low-pressure natural gas. Propane has different BTU content and pressure requirements.

Q: What if my pipe run exceeds 200 feet?
A: Longer pipe runs require larger diameter pipes. The calculator accounts for this through the pipe length input.

References