What Size Generator for House (Essentials)?
A whole-house generator is expensive. For emergency backup of essentials (fridge, lights, some outlets), a portable generator in the 5000-7500W range covers most needs without the cost of a standby unit.
Minimum Size
5000W
bare minimum, tight
Comfortable Size
7500W
recommended
Ideal Size
10000W
room to grow
Total Running Watts
2050W
Total Surge/Starting Watts
5600W
Generator Sizing Calculator
Additional Custom Load
Running Watts
2050W
Surge Watts
5200W
Recommended Generator
6500W+
Includes 25% headroom for reliable operation
Suitable Generator Sizes
Estimated Fuel Usage
* Fuel estimates are approximate. Actual consumption varies by generator model, load, and altitude.
Typical Loads for House (Essentials)
| Item | Running Watts | Surge Watts |
|---|---|---|
| Refrigerator | 200W | 600W |
| Freezer | 150W | 400W |
| Furnace Fan | 500W | 1000W |
| Sump Pump | 500W | 1500W |
| Well Pump (1/2 HP) | 500W | 1500W |
| Lights (10 LED bulbs) | 100W | 100W |
| Phone/Laptop Charging | 100W | 100W |
| Total | 2050W | 5600W |
* Surge watts apply to motor loads during startup. Size your generator for worst-case surge scenario.
Generator Sizing Tips
- •Never run a generator indoors or in a garage - carbon monoxide kills
- •Use a transfer switch or interlock kit for safe connection to house wiring
- •Stagger motor startups - don't start sump pump and well pump simultaneously
- •A 7500W generator with transfer switch covers most essential circuits
- •Keep fuel stabilized for long-term storage
Key Considerations
- ⚠Transfer switch installation requires electrician
- ⚠Fuel storage and rotation is critical
- ⚠Noise may bother neighbors in extended outages
Alternatives to Consider
- ✓Standby generator with automatic transfer
- ✓Solar + battery for silent backup
- ✓Propane generator for longer fuel storage
Frequently Asked Questions
What size generator to run a house?
For essentials (fridge, freezer, some lights, furnace fan), 5000W is minimum. For more comfort including well pump, sump pump, and more circuits, 7500W. For central AC or heat pump, 10,000W+.
Can I plug a generator into a wall outlet to power my house?
No! This is called backfeeding and is extremely dangerous. It can electrocute utility workers and damage your generator. Use a proper transfer switch or interlock kit.
How much fuel does a house generator use?
A 7500W generator uses about 0.5-0.75 gallons per hour at 50% load. Running essentials (not full load), expect 10-15 gallons per day.