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Gas Appliance Load Calculator

Work out gas appliance load instantly with clear inputs, formula shown and shareable results.

About Gas Appliance Load Calculator

Fuel gas systems are sized on total connected load, not on expected simultaneous use, because any appliance may fire at any time. The sum in BTU per hour divided by 1030 gives cubic feet per hour, and meters are specified with about 25 percent headroom so future appliances do not force a service upgrade.

Formulas

Connected load

Total BTU/h = sum of all appliance input ratings; ft³/h = total / 1030

Meter sizing

Meter ft³/h = demand x 1.25, rounded up to the next catalogue capacity

Worked example

With the default values below, Gas Appliance Load Calculator returns Total connected load of 207,000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Furnace or boiler inputminimum 0 BTU/h
80,000 BTU/h
Water heater inputminimum 0 BTU/h
40,000 BTU/h
Cooking appliance inputminimum 0 BTU/h
65,000 BTU/h
Other appliancesminimum 0 BTU/h
22,000 BTU/h

Results

Total connected load
207,000 BTU/h
Gas demand
201.0 ft³/h
Meter capacity to specify
275 ft³/h
Largest appliance share
38.6% %

Step by step

  1. 1Values used
  2. 2Connected load
  3. 3Meter sizing
  4. 4Total connected load= 207,000 BTU/h
  5. 5Gas demand= 201.0 ft³/h
  6. 6Meter capacity to specify= 275 ft³/h
  7. 7Largest appliance share= 38.6 %

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Preliminary estimate only. Confirm connected load, meter capacity and service pressure with the gas utility and a licensed installer.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Confirm connected load, meter capacity and service pressure with the gas utility and a licensed installer.

Frequently Asked Questions

How is the Gas Appliance Load figure worked out?

Total BTU/h = sum of all appliance input ratings; ft³/h = total / 1030. Fuel gas systems are sized on total connected load, not on expected simultaneous use, because any appliance may fire at any time.

Can I diversify the load like an electrical service?

Not for the piping. Gas codes require the full connected load for pipe sizing, although utilities may apply diversity when sizing the service main itself.

What values do I need to enter?

This calculator takes 4 inputs: Furnace or boiler input, Water heater input, Cooking appliance input, Other appliances. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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