Offline
No internet, no account required.
IFGC
Validated against the standard.
PDF export
Pro-only. Generate professional reports.
$2.99 Pro
Lifetime unlock. No subscriptions.
How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
Get a code-checked result
Instant answer with a clear PASS / FAIL and the exact IFGC reference behind every number.
Save & export
Keep a history of calculations and export a clean PDF report to share or attach to a permit (Pro).
What this calculator does
Gas pipe must deliver enough fuel to every appliance at the required pressure. This app sizes natural gas and propane piping by the longest-length method from the IFGC and NFPA 54, balancing total demand against pipe length and allowable pressure drop.
How it works
- Add up appliance demand in BTU/h (or convert to cubic feet per hour).
- Measure the longest run from the meter to the most remote appliance.
- Read the pipe size for each section from the capacity table for your pipe material, gas type, and pressure drop.
Worked example
A furnace (100,000 BTU/h) plus a water heater (40,000) and range (65,000) total 205,000 BTU/h. At a 60-foot longest length on natural gas at 0.5 in. w.c. drop, the main commonly sizes to about 1 to 1-1/4 inch depending on pipe material.
Related calculators
For water systems use the water pipe sizing calculator; for fixture counts the fixture unit calculator.
Gas pipe sizing FAQ
What is the longest-length method?
You size the whole system from the single longest run between the meter and the most remote appliance, which guarantees adequate pressure everywhere. It is the standard method in the IFGC and NFPA 54.
Natural gas and propane?
Both. They have different heating values and capacity tables, so the app uses the correct table for the gas type, pipe material, and operating pressure.
Does pipe material matter?
Yes. Steel, copper, and CSST each have their own capacity tables, so the same demand can call for a different size depending on the material.
Does it work offline?
Yes, it runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
Get Gas Pipe Sizing on your phone
Free with rewarded ads · $2.99 lifetime Pro · iOS & Android. Works 100% offline on the job site.