Choosing the right generator size protects your family during power outages.
But here’s the thing – if you ask me “what size generator do I need?” without knowing your specific power needs, you might end up with the wrong one.
This guide shows you exactly how to calculate your power needs, pick the perfect size, and avoid expensive mistakes. Take a few minutes to read through so you get it right the first time.
Why Generator Size Matters
Getting the wrong generator hurts your wallet and causes headaches.
A small generator overworks itself trying to power your home. Your appliances won’t run properly. The generator breaks down faster. You might even damage your expensive electronics.
A big generator wastes your money. You pay more upfront for power you don’t use. You burn extra fuel. The generator runs inefficiently because it’s not working at the right level.
The right size saves you money and keeps your family comfortable when the power goes out.
Understanding Watts: The Basics
Every appliance in your home uses watts to run. Your refrigerator needs about 700 watts. Your air conditioner might need 3,500 watts.
You need to know two types of watts:
Running Watts: The power your appliance needs to keep operating. Think of this like driving at a steady speed on the highway.
Starting Watts: The extra burst of power some appliances need when they first turn on. Think of this like the gas you need to accelerate from a stoplight.
Appliances with motors need way more power to start than to run. Your refrigerator might use 700 watts to run but needs 2,200 watts to start. This matters when sizing your generator.
How to Calculate Your Power Needs
Follow these four simple steps.
Step 1: List Your Essential Appliances
Write down everything you must run during an outage:
- Refrigerator and freezer
- Lights (a few rooms)
- Phone and device chargers
- Internet router
- Heating or cooling system
- Well pump (if you have one)
- Medical equipment (if needed)
- Sump pump (if you have one)
Step 2: Find the Wattage
Check the label on each appliance. It shows watts or amps.
If you only see amps, multiply by 120 to get watts.
Example: 5 amps × 120 = 600 watts
Step 3: Add Up Your Total
Add all running watts together. Find the highest starting watts on your list.
Your formula: Total Running Watts + Highest Starting Watts = Minimum Generator Size
Step 4: Add a Safety Buffer
Add 20% more to your total. This protects your generator and gives you room for one more item.
Complete Generator Size Chart
This chart helps you choose fast. No guessing needed.
| Generator Size | Home Type | What You Can Run | Best For |
|---|---|---|---|
| 2,000-3,500 Watts | Small Apartments | Refrigerator, 3-5 lights, TV, phone chargers, laptop, fan or space heater, internet router | Studio or 1-bedroom apartments, emergency essentials, camping, tailgating, job sites |
| 3,500-5,000 Watts | Medium Homes | Refrigerator and freezer, 6-8 lights, TV and entertainment, multiple chargers, computers, microwave, sump pump, garage door, small window AC | 1-2 bedroom homes, small families, RV use, most homeowners |
| 5,000-7,500 Watts | Large Homes | All of above plus 10-15 lights, multiple TVs, washing machine, well pump, small central AC, coffee maker, water heater (small) | 3-bedroom homes, families wanting comfort, homes with well pumps |
| 7,500-10,000+ Watts | Extra Large Homes | Everything in your home with smart management, central AC (medium), electric range, dryer, all bathrooms, home office equipment | 4+ bedroom homes, whole-house backup, large AC systems, minimal lifestyle changes |
Small Apartments (2,000-3,500 Watts)
This size keeps your essentials running. Your food stays fresh. Your devices stay charged. You get some light and entertainment.
Perfect for smaller spaces where you only need the basics. Great for camping trips too.
Medium Homes (3,500-5,000 Watts)
This is the sweet spot for most families. You can run your refrigerator and freezer at the same time. You keep several rooms lit. Your internet stays on. You can even run a small air conditioner.
You need to manage what runs together. Don’t run your microwave and air conditioner at the same time. But you get real comfort, not just survival mode.
🔥 TOP PICK: ERAYAK 4500W Dual-Fuel Portable Inverter Generator
This generator solves most homeowners’ needs perfectly. Here’s what makes it special.
You can run it on gasoline or propane. This dual-fuel feature saves you during emergencies when one fuel runs out. The 4500 starting watts power all your essential appliances with room to spare.
The inverter technology protects your phones, laptops, and TVs from power surges. If you own an RV, the 30A outlet works perfectly for weekend trips. The auto switch automatically changes between fuels if one runs out.
Safety comes first with the built-in CO sensor. It shuts down automatically if dangerous carbon monoxide builds up. You can connect two units together if you need more power later. The compact design fits easily in your garage.
It meets EPA environmental standards. This generator gives you professional features at a fair price.
💰 BUDGET-FRIENDLY ALTERNATIVE: maXpeedingrods 4000W Dual Fuel Inverter Generator
Want to save money but still get great features? This one delivers.
The Bluetooth control lets you start and monitor from your phone. No more going outside in bad weather to check on it. The 4000 starting watts handle most home essentials easily.
Electric start means no pulling cords. Dual fuel gives you flexibility. It runs ultra-quiet so your neighbors stay happy. Works for both home backup and camping.
PGMA compliance means it meets strict quality standards. You get modern features at a lower price.
Large Homes (5,000-7,500 Watts)
This range brings real comfort during outages. Your life feels almost normal.
You run your refrigerator and freezer continuously. You keep 10-15 lights on throughout your home. Multiple TVs work for family entertainment. Your computer systems stay running for work.
You can use your microwave and coffee maker. Your washing machine works. Small central AC or multiple window units keep you comfortable. If you have a well pump or sump pump, this size handles them.
This works great for three-bedroom homes and families who want more than basics.
Extra Large Homes (7,500-10,000+ Watts)
This is serious backup power. You run almost everything with smart management.
All your refrigerators and freezers stay on. Every light in your house works. All electronics and TVs operate normally. Medium-sized central AC keeps your home comfortable.
You can use your electric range for cooking. Washing machine and dryer work separately. Well pump provides steady water pressure. Electric water heater gives everyone hot showers.
Perfect for four-bedroom homes or larger. Great if you experience frequent outages. Your lifestyle barely changes during power loss.
Common Appliances Wattage Reference
Use these tables when you calculate your needs.
Kitchen Appliances
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Refrigerator | 600-800 | 1,200-2,200 |
| Freezer | 500-700 | 1,200-1,500 |
| Microwave (1000W) | 1,000 | 1,000 |
| Coffee maker | 1,000 | 1,000 |
| Toaster | 850-1,500 | 850-1,500 |
| Electric stove (per burner) | 1,500-3,000 | 1,500-3,000 |
| Dishwasher | 1,200-1,500 | 1,200-1,500 |
Heating & Cooling
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Central AC (2 ton) | 3,500 | 9,000 |
| Central AC (3 ton) | 5,000 | 15,000 |
| Window AC (10,000 BTU) | 1,200 | 3,600 |
| Electric furnace fan | 700-1,500 | 700-1,500 |
| Space heater | 1,500 | 1,500 |
| Ceiling fan | 60-100 | 60-100 |
Water & Plumbing
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Sump pump (1/3 HP) | 800 | 1,300 |
| Sump pump (1/2 HP) | 1,050 | 2,150 |
| Well pump (1/2 HP) | 1,000 | 2,100 |
| Well pump (1 HP) | 2,000 | 4,000 |
| Water heater (40 gal) | 4,000 | 4,000 |
Laundry & Cleaning
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Washing machine | 1,200 | 1,200 |
| Electric dryer | 5,400 | 5,400 |
| Vacuum cleaner | 1,400 | 1,400 |
Lighting & Electronics
| Device | Watts Needed |
|---|---|
| LED bulb (60W equivalent) | 10 |
| CFL bulb | 15 |
| Incandescent bulb | 60 |
| TV (LED, 50″) | 150 |
| Laptop | 50-100 |
| Desktop computer | 200-500 |
| Internet router | 10-20 |
| Phone charger | 5-10 |
Other Important Items
| Item | Running Watts | Starting Watts |
|---|---|---|
| Garage door opener | 550-1,100 | 550-1,100 |
| Electric drill | 600-900 | 600-900 |
| Circular saw | 1,400-1,800 | 1,400-1,800 |
Portable vs Standby Generators
You choose between two main types. Each fits different needs.
Portable Generators
These cost $300 to $1,500. You can move them around. Use them at home, camping, or job sites.
No installation needed. You store them easily. If you move, your generator moves with you.
You set them up manually when the power goes out. You store fuel separately. They run for limited hours per tank. You must place them outside every time.
Best for most homeowners who want affordable, flexible backup power.
Standby Generators
These turn on automatically during outages. They connect to your natural gas or propane line. They power your whole house. You do nothing when the power goes out. They run indefinitely.
But they cost $3,000 to $15,000 or more. Professional installation adds $1,000 to $2,500. They stay in one location. You can’t take them when you move. They need regular professional maintenance. Most areas require permits.
Best for frequent outages, medical equipment needs, or maximum convenience.
Important Safety Rules
Follow these rules every time. They save lives.
Carbon Monoxide Safety (Critical!)
Carbon monoxide kills. You can’t see it or smell it. Generators produce it.
Never run your generator inside your home. Never run it in your garage, even with the door open. Never run it in your basement. Keep it away from windows and doors. Keep it away from air vents.
Place your generator at least 20 feet from your home. Point the exhaust away from all buildings. Install CO detectors in your home. Use a generator with a CO sensor like the ERAYAK model above.
Electrical Safety
Ground your generator properly. This prevents electric shock.
Use heavy-duty outdoor extension cords. Match the cord rating to your wattage needs. Never overload cords. Keep cords away from water. Don’t run cords under rugs or through doorways.
If you connect to your electrical panel, you must install a transfer switch. This prevents back-feeding electricity that kills utility workers and damages your generator.
Never plug your generator into a wall outlet. Never touch it with wet hands. Never operate it in rain without proper weatherproof covering.
Fuel Safety
Only add fuel when your generator is off and cool. Hot generators can explode.
Store gasoline in approved containers only. Keep fuel far from the generator and heat sources. Don’t store more than a few months’ worth. Add fuel stabilizer for storage.
For propane, check for leaks regularly. Store tanks upright outdoors. Keep tanks away from heat. Follow all local fire codes.
Maintenance Schedule
Check oil level before every use. Look for damage or leaks. Make sure the air filter looks clean.
Run your generator for 15-30 minutes monthly, even without outages. This keeps parts lubricated. It keeps the battery charged.
Change oil every six months. Replace or clean the air filter. Check the spark plug. Drain old fuel and add fresh fuel with stabilizer.
Do a complete tune-up yearly. Check all connections. Test with full load.
Gas vs Propane: Understanding Dual-Fuel
Both recommended generators run on gas or propane. This matters.
Gasoline Facts
You find gas easily at any gas station. It costs less per gallon. It provides more power per gallon. Small containers store easily.
But gasoline goes bad in three to six months. You must add stabilizer. It requires more generator maintenance. You can’t safely store large amounts at home.
Propane Facts
Propane lasts forever. It never goes bad. It burns cleaner so your generator needs less maintenance. You can store large quantities safely. If you have a propane grill, you already know how to use it.
Propane produces about 10% less power. You need tanks and storage space. It might be less available in some areas.
Why Dual-Fuel Wins
Dual-fuel generators eliminate problems. Use gas when you need maximum power. Switch to propane for long emergencies. If one fuel runs out, you have backup.
This flexibility prepares you for any situation. That’s why we recommend the ERAYAK 4500W and maXpeedingrods 4000W. Smart choice for your family.
Real Examples: What Size Do You Need?
Let’s look at real families and their needs.
Example 1: Young Couple, 2-Bedroom Home
What they need to run:
- Refrigerator: 700 watts running, 2,200 starting
- 5 LED lights: 50 watts
- TV: 150 watts
- Internet router: 20 watts
- 2 phone chargers: 10 watts
- Laptop: 75 watts
- Window AC: 1,200 watts running, 3,600 starting
Total: 2,205 running watts + 3,600 starting watts = 5,805 watts needed
Best choice: 4,000-4,500 watt generator
Perfect match: ERAYAK 4500W
Example 2: Family of Four, 3-Bedroom Home
What they need to run:
- Refrigerator: 700 watts running, 2,200 starting
- Freezer: 600 watts running, 1,500 starting
- 10 LED lights: 100 watts
- 2 TVs: 300 watts
- Internet router: 20 watts
- 4 phone chargers: 20 watts
- Laptop: 75 watts
- Sump pump: 800 watts running, 1,300 starting
- Small central AC fan: 700 watts
Total: 3,315 running watts + 2,200 starting watts = 5,515 watts needed
Best choice: 4,500-5,500 watt generator
Perfect match: ERAYAK 4500W gives you room for a microwave too.
Example 3: Large Family with Well Pump
What they need to run:
- Refrigerator: 700 watts running, 2,200 starting
- Freezer: 600 watts running, 1,500 starting
- 12 lights: 120 watts
- Well pump (1/2 HP): 1,000 watts running, 2,100 starting
- Sump pump: 800 watts running, 1,300 starting
- 2 TVs: 300 watts
- Electronics: 200 watts
- Small window AC: 1,200 watts running, 3,600 starting
Total: 4,920 running watts + 3,600 starting watts = 8,520 watts needed
Best choice: 8,000-9,000 watt generator
Note: You need a larger unit, or connect two ERAYAK generators in parallel.
Money-Saving Tips
Get more value from your investment.
Buy During Off-Season
Generator prices jump before hurricane season (May-November) and late fall. Buy in spring or early summer instead. You save 20-40% on the same models.
Know Your Total Costs
Here’s what you actually spend:
| Cost Category | Amount | When You Pay |
|---|---|---|
| Initial Costs | ||
| Generator unit | $400-$1,000 | One-time |
| Transfer switch (optional) | $200-$500 | One-time |
| Heavy-duty extension cords | $50-$100 | One-time |
| Covers and accessories | $50 | One-time |
| Operating Costs | ||
| Fuel during outages | $5-$15 | Per day of use |
| Oil changes | $20-$30 | Yearly |
| Maintenance | $50-$100 | Yearly |
Most homeowners spend less than $100 yearly on maintenance. Fuel costs only matter during actual outages.
Reduce Your Power Needs
Smart management lets you buy a smaller, cheaper generator.
Stagger when you turn on big appliances. Run your well pump to fill the tank, then switch to AC. Don’t run them together.
Turn off non-essential items. You don’t need game consoles during emergencies.
Replace old bulbs with LEDs. They use 75% less power. Your lighting drops from hundreds of watts to 50-100 watts total.
Unplug devices you’re not using. Many draw power even when turned off.
These habits can downsize your needs from 5,000 watts to 4,000 watts. You save $200-400 on the purchase price.
Frequently Asked Questions
Can I run my generator in the rain?
You need a proper weatherproof cover designed for generators. Never run it in direct rain without protection. Water and electricity kill.
How long can I run it continuously?
Most portable generators run 8-12 hours on a full tank. Give it a break every 18-24 hours to cool down. Check the oil.
Will it power my whole house?
Generators in the 4,000-5,000 watt range power essentials but not everything at once. You manage what runs. For true whole-house power, you need 10,000+ watts or a standby unit.
How loud are these generators?
Inverter generators run at 50-60 decibels. That’s like a normal conversation. Traditional generators hit 70-80 decibels, like a vacuum cleaner.
Do I need an electrician?
For portable generators with extension cords – no. For transfer switch installation connecting to your panel – yes, absolutely. Code requires it. Safety demands it.
Can I use it camping?
Yes! Both the ERAYAK 4500W and maXpeedingrods 4000W work great for camping. They’re compact and quiet enough for campgrounds.
What’s an inverter generator?
Inverter generators produce “clean” power safe for electronics. Regular generators can damage laptops, phones, and TVs. Inverter generators also run quieter and more efficiently.
How often should I run it if I’m not using it?
Run it 15-30 minutes every month. This keeps everything lubricated. It prevents fuel system problems.
Make Your Final Decision
You now know how to choose the right generator.
Calculate your essential running watts first. Add your highest starting watts. Add 20% for safety. Consider dual-fuel a must-have, not optional. Prioritize safety features like CO sensors.
Our Top Recommendations
Best Overall Choice: ERAYAK 4500W Dual-Fuel Portable Inverter Generator
This generator checks every box. It provides 4500 starting watts – enough for most homes. Dual-fuel gives you flexibility. The CO sensor protects your family. EPA certification means environmental compliance.
Inverter technology protects your electronics. Parallel-ready lets you expand later. Compact design stores easily. You get professional features at a fair price.
Best Budget Choice: maXpeedingrods 4000W Dual Fuel Inverter Generator
Perfect if you want to save money without sacrificing quality. Bluetooth control from your phone adds convenience. Electric start eliminates cord pulling.
4000 starting watts handle most essential needs. Dual fuel at a lower price point. Ultra-quiet operation. RV-ready. PGMA compliant.
Both generators serve your family reliably during outages.
Final Thoughts
The right generator keeps your family safe and comfortable when storms knock out power.
You now know how to calculate needs, choose the right size, and pick between excellent options. Get your generator today and sleep better knowing you’re ready for the next outage.
