What size generator do you need? In most cases, the right answer is based on your electrical load, not just the size of your house. For a propane standby generator, you should total the items you want to run during an outage, account for the biggest motor-starting load, and decide whether you want to cover only essential circuits or most of the home. Generator size is measured in kilowatts (kW), and a larger unit can support more circuits, but it will also use more propane.
How to size it correctly
We recommend starting with three questions:
- What absolutely needs to stay on during an outage?
- Which appliances have motors that need extra startup power?
- Do you want “essentials only,” or do you want the home to feel close to normal?
Generac guidance notes that home standby systems should be sized to exceed the continuous load you plan to run, while also accounting for motor-driven appliances such as refrigerators, well pumps, and air conditioners that draw extra power when starting. And tools such as Generac’s Solution Finder and the Briggs & Stratton sizing calculator both frame the decision around what you want to power, not simply square footage.
| What to evaluate | Why it matters |
| Essential circuits | This sets your minimum kW target |
| Largest motor load | Startup demand can exceed normal running demand |
| Electric dryer, range, or large A/C | These can push you into a much larger generator |
| Whole-home comfort goals | This determines whether load management is acceptable |
A practical way to think about size
If you only want refrigeration, a few lights, internet, a sump pump, and a furnace blower, you can often size for select circuits. If you want central air, more kitchen loads, laundry, or broader whole-home coverage, your kW requirement climbs quickly. In our experience at Collett, a 16 kW generator may work well for many homes, but in a larger house it may still require choosing which loads run at the same time. Moving up in size can provide more comfort and fewer tradeoffs during an outage.
That said, our recommendation to “go a little bigger if you are already making the investment” is just that: our recommendation, not a universal rule. Manufacturers also note that accessories and load management can reduce the need to oversize, which can help control cost and fuel consumption.
Do not ignore propane consumption
Bigger generators do not just provide more power; they also burn more fuel. For example, Generac lists its 22 kW home standby unit at about 2.53 gallons of propane per hour at 50% load and 3.71 gallons per hour at full load. That is why generator sizing and propane storage should be planned together. On our side, tank sizes vary by home, appliance count, and site layout, and larger generators are commonly paired with larger propane storage.
Local installation support and next steps
When customers need generator installation support, we can help coordinate with trusted local contractors such as A-Abel and Wells Electric, both of which publicly offer backup generator installation and service in the Dayton area.
If you are deciding between generator sizes, our best advice is simple: list the loads you want to carry, run them through an official calculator, and then let us help you match that generator to the right propane setup. To get started with Collett, use our contact form and select “Generators” so we can help you plan the right system for your home.