Gas Meter Size for a Whole-Home Generator (250 vs 400+ CFH)
Why the gas meter is often the bottleneck
Natural gas carries roughly 1,000 BTU per cubic foot, so a meter rated 250 CFH can supply roughly 250,000 BTU per hour. A typical furnace, water heater and range together can already use a large share of that. Add a 20–26 kW standby generator running at full load and the total can exceed what the meter (and sometimes the service line and regulator) can deliver, which starves the generator of fuel under load.
How to read your meter rating
The meter's model number is printed on its faceplate. Models with "250" in the name (for example AC-250) are commonly rated around 250 CFH; models such as AL-425 or AL-630 are higher-capacity residential meters. If you are not sure, take a photo of the faceplate and ask your gas utility.
How to add up your gas load
- Find the input rating in BTU/hr on each appliance's nameplate: furnace, water heater, range/oven, dryer, fireplace, pool heater.
- Find your generator's gas consumption at full load on its spec sheet (listed in CFH or BTU/hr).
- Add everything together and divide BTU/hr by about 1,000 to get CFH.
- Compare the total with your meter's rating. Use our gas meter calculator for a quick estimate.
A licensed plumber or gas fitter must also size the gas piping from the meter to the generator under your local fuel gas code — a bigger meter does not help if the pipe is too small.
Requesting a larger meter
Gas utilities usually ask for a load letter or service request listing every appliance and its BTU rating. Lead times and fees vary by utility, from no charge to a significant fee when the service line or regulator also has to change. Submit the request early — before the generator is delivered.
Frequently asked questions
Can a 250 CFH gas meter run a 22 kW generator?
Sometimes, but often not together with your other appliances. Many 22 kW natural gas generators use roughly 300 CFH or more at full load, which on its own can exceed a 250 CFH meter. Check your generator's spec sheet and add your appliance load.
Who pays for a gas meter upgrade?
It depends on your gas utility's tariff. Some upgrade the meter at little or no cost; others charge, especially if the service line or regulator must be replaced. Ask your gas utility for a written quote.
Do I need a bigger meter for a home battery?
No. Battery systems such as Powerwall do not use natural gas, so they do not affect your gas meter.