A gas meter and its first-stage regulator must be able to deliver the peak gas demand of every appliance behind it. This calculator sums each appliance’s BTU/h input, applies a realistic diversity factor, converts the result to standard cubic feet per hour for natural gas or propane, and checks it against the rated meter capacity so you can confirm the service is adequate before you connect a new appliance.
How it works
Three steps turn a list of appliances into a meter capacity check:
connected load = Σ appliance BTU/h
design demand = connected load × diversity factor
SCFH = design demand / heating value per cubic footThe heating value is about 1030 BTU per cubic foot for natural gas and 2516 for propane vapor, so the same BTU/h load draws far fewer cubic feet of propane. The design demand in SCFH is then compared to the meter or regulator’s rated SCFH; if demand exceeds capacity the service is undersized.
Typical residential appliance BTU/h ratings
For reference when populating the appliance list:
| Appliance | Typical input BTU/h |
|---|---|
| Gas furnace (residential) | 60,000–120,000 |
| Tankless water heater | 120,000–200,000 |
| Tank water heater | 30,000–50,000 |
| Gas range/cooktop | 35,000–65,000 |
| Gas dryer | 20,000–30,000 |
| Gas fireplace (decorative) | 20,000–40,000 |
| Gas fireplace (heating) | 30,000–80,000 |
| Pool heater | 100,000–400,000 |
Always use the actual nameplate rating from the appliance data label or manufacturer specifications — these are typical ranges, not the values to enter for a real load calculation.
Understanding the diversity factor
A residential diversity factor of 0.80 reflects the practical reality that appliances rarely all fire simultaneously at full load. In a typical home, the furnace is usually the dominant load and is oversized for design conditions; it cycles. The water heater fires intermittently. The range is used at mealtimes.
The 0.80 factor is appropriate for most residential calculations. Use 1.00 (no diversity) for:
- Commercial kitchens where multiple burners run continuously
- Industrial processes with continuous simultaneous loads
- Any jurisdiction or utility that mandates full connected load
- Installations where the engineer needs a conservative margin
Example and tips
A furnace at 80,000, a water heater at 40,000, and a range at 65,000 BTU/h give a connected load of 185,000 BTU/h. With a 0.80 diversity factor the design demand is 148,000 BTU/h, which on natural gas is about 144 SCFH — comfortably inside a 250 SCFH meter. Adding a gas dryer at 25,000 BTU/h raises the connected load to 210,000 and the design demand to 168,000 BTU/h (163 SCFH) — still within the 250 SCFH meter but worth noting before any additional appliances are considered.
Always confirm the diversity factor your jurisdiction allows; some authorities require full simultaneous demand for commercial kitchens and other high-use occupancies.