SettingsSettings for this calculationUS
The pipe's internal diameter.
Use the actual internal diameter of the fuel gas pipe, not its nominal size.
The maximum gas velocity the pipe should be allowed to carry.
Fuel gas pipe sizing commonly limits velocity to around 6 m/s (roughly 20 ft/s) to control noise and erosion, though the exact limit can vary by application.
Pipe flow capacity (m³/h)
10.9 m³/h
This is a simplified velocity-based capacity screening check — actual fuel gas pipe sizing per NFPA 54/IFGC also depends on allowable pressure drop, pipe length, and fitting losses, and must use the code's official sizing tables for final design.
- Capacity in CFH, the unit US gas tables use
- 386.51 CFH
They open the calculator with your figures already in it
Fuel Gas Pipe Capacity Calculator: 10.94 m³/h — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- Capacity = pipe cross-sectional area × maximum allowable gas velocity, a simplified velocity-based screening check consistent with NFPA 54/IFGC gas pipe sizing principles (which also account for pressure drop and pipe length via sizing tables)
Inputs used
- Pipe internal diameter
- 1 in
- Maximum allowable gas velocity
- 19.69 ft/s
Intermediate steps
- Capacity in CFH, the unit US gas tables use
- 386.51 CFH
Confidence note: This is a simplified velocity-based capacity screening check — actual fuel gas pipe sizing per NFPA 54/IFGC also depends on allowable pressure drop, pipe length, and fitting losses, and must use the code's official sizing tables for final design.
What this calculation does not cover
- A volume flow is not what an appliance is rated in. Demand arrives as a heat input, and converting between the two needs the fuel's calorific value — natural gas around 1,000 BTU/ft³ (37 MJ/m³), propane about 2,500 BTU/ft³ (93 MJ/m³) — so the same pipe at the same velocity delivers roughly two and a half times the energy on propane. Matching a volume figure straight against a nameplate input is the easiest way to be wrong by a whole factor.
- Gas is compressible, so capacity depends on pressure and there is no pressure field on this page. Velocity is what is fixed here, but the mass moving at that velocity follows the density: the same pipe carries far more gas at 2 psi (14 kPa) than at 7 in w.c. (1.7 kPa), which is precisely why a two-pound system with regulators at the appliances lets a smaller pipe serve a bigger house. The code tables are indexed on supply pressure and allowable drop for that reason.
- Each section has to carry everything downstream of it at once. Fuel gas is sized with no diversity allowance — the length leaving the meter takes the full connected input of every appliance beyond it simultaneously — and the capacity of one pipe says nothing about that total. Nor about the meter and service regulator upstream of it, which are the real ceiling on what the building can draw however generously the pipe itself is sized.
Add the equipment this sizes
This result is a specification — 10.9 m³/h — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Capacity = pipe cross-sectional area × maximum allowable gas velocity, a simplified velocity-based screening check consistent with NFPA 54/IFGC gas pipe sizing principles (which also account for pressure drop and pipe length via sizing tables)
Which documents these citations point at
- National Fuel Gas Code (NFPA 54) (United States)Fuel gas piping systems, appliance installation and venting, including the longest-length sizing method.
- International Fuel Gas Code (United States)Fuel gas piping, appliances and venting. Its sizing provisions track NFPA 54.
A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.