Running load
Power used once the equipment is operating.
Mister Safety · Generac Dealer
What Size Standby Generator Does Your Home Need?
Generator sizing depends on what will run together and what must start while other equipment is operating. Square footage and the main-breaker size do not answer those questions by themselves. Your air conditioner, pumps, cooking equipment and future loads should be reviewed as part of the backup plan.
- Our office answers 24/7 (888) 308-6766
- Prefer to book online? Book with Housecall Pro →
Licensed & Insured #EC13016024 5.0 on Google · Homeowner reviews
Request your installation estimate
01 / Generator Sizing
Size the system around real equipment.
Start with what must operate together. We review the equipment demand, the electrical service and the intended coverage, then consider how motors start while other loads are running. Square footage and the main-breaker label alone cannot establish the right generator.
Heating type, air conditioning, pumps, cooking equipment and future EV charging all belong in the planning conversation. Your priorities help determine which loads need backup and which can wait.
Your conversation checklist
Select priorities to prepare your estimate discussion.
Use these priorities in my request →No appliance wattages, system size or price are inferred.
Sources: Generac · Find the Right Generator
02 / Generator Sizing
Running power and starting demand are different.
A motor can briefly need more from the source as it starts than it does while running. An air conditioner or well pump therefore needs equipment-specific review, not just a generic appliance wattage from a chart.
A compatible HVAC soft starter may be a design option. It does not create generating capacity, and it should not be presented as a universal fix for an undersized system.
Starting demand
The brief demand when a motor accelerates.
Simultaneous use
The other loads already operating when that motor starts.
03 / Generator Sizing
A 200 A switch does not create 200 A of backup.
The transfer switch’s current rating describes the switching equipment. The generator remains the power source. These ratings serve different purposes.
For a simplified single-phase, power-factor-one example: 24,000 W ÷ 240 V = 100 A. This arithmetic explains the distinction; it is not a conductor, breaker or installation design calculation.
Illustrative 240 V example24,000 W ÷ 240 V = 100 A
Generator output and transfer-switch current rating are different quantities in the equipment selection.
Sources: Generac · 22-28 kW Air-Cooled Home Standby Generators specification sheet / Generac · 100 A Automatic Transfer Switch, G0099340
Bring your questions. We’ll help you define the next step.
Get a Standby Generator Installation Estimate04 / Generator Sizing
Read the fuel rating beside the model number.
The same model can have different natural-gas and propane ratings. The current cellular G0072820 example is rated 28 kW on propane and 25 kW on natural gas. Guardian G0070430 is a different generation, rated 22 kW on propane and 19.5 kW on natural gas.
Compare the full model number, its actual fuel and the complete system. A familiar “22 kW” label does not mean every generation has the same output or controls.
| Example | Propane | Natural gas |
|---|---|---|
| Cellular G0072820 | 28 kW | 25 kW |
| Guardian G0070430 | 22 kW | 19.5 kW |
Sources: Generac · Standby Generator, 28 kW | Cellular, G0072820 / Generac · 22 kW Standby Generator with Whole House Switch, Wi-Fi, G0070430
05 / Generator Sizing
Prepare for the assessment without opening equipment.
Make a list of your cooling systems, pumps and other priorities. If readily available in your records, note model information and planned additions. You do not need to remove a cover, touch wiring or perform a live test.
Accessible exterior information can help preparation. A photo cannot determine electrical safety, service capacity or the final generator size.
A little more clarity
Your questions, answered.
Will a 22 kW generator run my whole house?
It depends on the exact model, fuel and required demand; the number alone is insufficient.
Does an AC soft starter solve sizing?
It may be a compatible design option, but it does not create more generating capacity.
Can a photo determine the size?
Accessible information helps preparation; photos cannot replace assessment.
Keep planning your standby system.
← Back to the Standby Generator HubYour home. A clearer backup plan.
Let’s turn your questions into a plan.
A free estimate prices a defined installation. Troubleshooting an unexplained fault is separate paid diagnostic work, with charges explained before approval.
A request is not a confirmed appointment. We confirm availability for your Florida address and project. Privacy policy.
Research checked September 10, 2026. Exact model instructions, the assessed property and applicable local requirements govern the installation. Product details and offers can change.
Sources and further reading
- Find the Right GeneratorGenerac · Undated live sizing flow
- 22-28 kW Air-Cooled Home Standby Generators specification sheetGenerac · Part A0005151077, Revision D, August 13, 2026
- 100 A Automatic Transfer Switch, G0099340Generac · Undated live product page
- Standby Generator, 28 kW | Cellular, G0072820Generac · Undated live product page
- 22 kW Standby Generator with Whole House Switch, Wi-Fi, G0070430Generac · Undated live product page