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Calculators / Outdoor kitchen

What size gas line does my grill need?

Put in the total Btu on the line and the length from the meter. You get the gas flow and the smallest steel pipe that carries it, from the fuel gas code table.

Updated · How we check our numbers

These are example numbers. Put in yours.

The run

Btu/h

Add up the rating plates: grill, side burner, fire pit, heater.

ft

Along the pipe to the farthest appliance, not the straight line.

Pipe size

3/4 in black iron

90,000 Btu/h is about 87 cubic feet of gas an hour. Over 50 ft (the 50 ft row), 3/4 in Schedule 40 pipe carries 151 cfh.

Demand
87 cfh90,000 Btu/h
Table row
50 ft
Capacity
151 cfh

Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.

demand = 90,000 Btu/h ÷ 1,036 Btu/cu ft = 87 cfh

length 50 ft → 50 ft row of IFGC Table 402.4(2)

Schedule 40 steel pipe

IFGC Table 402.4(2), 0.5 in. w.c. drop
  • 1/2 in pipe72 cfh at 50 ft
    Too small
  • 3/4 in pipe151 cfh at 50 ft
    Smallest that works
  • 1 in pipe284 cfh at 50 ft
    Works
  • 1 1/4 in pipe583 cfh at 50 ft
    Works
  • 1 1/2 in pipe873 cfh at 50 ft
    Works
  • 2 in pipe1680 cfh at 50 ft
    Works
Permit and a licensed fitter

Gas piping needs a permit and a pressure test in nearly every town, and many require a licensed gas fitter or plumber. Use this to check the plan, not to skip that.

Whole system

The length is from the meter to the farthest appliance, and the load is everything on that branch. If the grill tees off a line that also feeds a furnace or range, the shared section has to carry all of them.

Flexible (CSST) pipe

Corrugated stainless tubing carries less than steel pipe of the same nominal size; size it from its maker's table.

How we work it out

cubic feet an hour = Btu/h ÷ 1,036; then the IFGC table row for your length, rounded up

The table is IFGC Table 402.4(2), Schedule 40 metallic pipe at under 2 psi with a 0.5 in. water column pressure drop, as published in Seattle's 2018 Fuel Gas Code. Use the full length from the meter to the farthest appliance, which is the code's longest-length method. EIA puts natural gas at 1,036 Btu a cubic foot; your gas utility can give you the local figure.

Where the numbers come from

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