Gas Pipe Sizing Calculator

Size natural gas piping using the longest run method with Weymouth formula per IFGC standards.

Total BTU Load

BTU/hr

Longest Pipe Run

Inlet Pressure

psi

Gas Specific Gravity

Tab to move between fields

Required Pipe Size

1 inches

Pipe Capacity

335,889 BTU/hr

Pressure Drop0.01 psi

Gas Velocity10.19 fps

How to Use This Calculator

Enter the total BTU load — sum the input ratings of all gas appliances (furnace, water heater, range, dryer).
Enter the longest pipe run in feet from the meter to the farthest appliance.
Set the inlet pressure (typically 0.25 PSI for residential, 2 PSI for medium-pressure systems).
Leave specific gravity at 0.60 for natural gas, or adjust for propane (1.52).
Review Required Pipe Size and verify that the calculated pressure drop stays within the allowable limit.

Ad Placeholder

Related Calculators

Size water supply piping based on fixture units, building height, available pressure, and pipe run length.

Determine the correct backflow prevention device type, size, pressure loss, and estimated installation cost based on hazard level.

Ad Placeholder