Use this simple planning table to estimate how much backup power your household may need during a blackout. The basic formula is:
Watts × Hours Used = Watt-Hours Needed
After you total your watt-hours, add about 25% extra buffer for startup surges, battery loss, weather, and real-world use.
This emergency power planner helps estimate how much backup power you may need during a blackout.
Common Blackout Power Estimates
Item
Estimated Watts
Hours Used
Daily Watt-Hours
Priority
Refrigerator
700W
8 hrs
5,600Wh
High
Freezer
500W
6 hrs
3,000Wh
High
CPAP Machine
60W
8 hrs
480Wh
Critical
Box Fan
75W
8 hrs
600Wh
High in summer
LED Lights / Lanterns
25W
6 hrs
150Wh
High
Phone Charging
15W
3 hrs
45Wh
High
Emergency Radio
10W
4 hrs
40Wh
High
WiFi Router
20W
6 hrs
120Wh
Medium
Laptop
65W
4 hrs
260Wh
Medium
Coffee Maker
900W
15 min
225Wh
Low
Microwave
1,200W
15 min
300Wh
Low
Sump Pump
800W
2 hrs
1,600Wh
Critical if flooding
Example Backup Power Setups
Basic Setup
Phones, lights, radio, and small charging needs.
Estimated need: 300–800Wh
Best fit: Small power station or power banks.
Comfort Setup
Phones, lights, fan, CPAP, router, and radio.
Estimated need: 1,000–2,500Wh
Best fit: Mid-size power station.
Food Protection Setup
Refrigerator, freezer, lights, phones, and radio.
Estimated need: 4,000–9,000Wh
Best fit: Large battery system or generator.
Heavy Use Setup
Fridge, freezer, sump pump, cooking appliances, fans, and devices.
Estimated need: 8,000Wh+
Best fit: Generator or expandable solar generator system.
Quick Planning Formula
Add up the watt-hours for every item you need to run in one day. Then multiply that number by 1.25 to add a safety buffer.
Total Watt-Hours × 1.25 = Recommended Battery Size
Example: If your household needs 2,000Wh per day, you should look for at least a 2,500Wh battery setup before solar recharging, generator charging, or fuel use is considered.
Most People Buy Too Much Power — Or Not Enough
The goal is not powering your whole house like normal. The goal is keeping critical systems running: food storage, medical devices, cooling, lights, communication, and basic safety.
What Drains Backup Power Fastest?
Device
Why It Drains Power
Best Blackout Strategy
Coffee Maker
Heating element pulls heavy watts.
Use propane, butane, or manual brewing.
Microwave
High draw for short bursts.
Avoid unless you have a large system.
Space Heater
Constant heavy draw.
Use safer non-electric heat planning.
Window AC
Compressor surge and long runtime.
Use fans, shade, and cooling zones first.
Well Pump
Startup surge can be high.
Usually generator territory.
Solar Generator vs Gas Generator
Feature
Solar Generator / Power Station
Gas Generator
Indoor Use
Safe indoors when used properly.
Never run indoors.
Noise
Quiet.
Loud.
Fuel
Battery + solar recharge.
Gas, propane, or dual fuel.
Best For
Phones, lights, CPAP, fans, fridge support.
Heavy loads, long outages, whole circuits.
Weakness
Limited capacity unless expanded.
Needs fuel storage and ventilation.
How Most Blackout Power Plans Fail
Most households do not run out of power all at once. They slowly lose capability as batteries drain, fuel disappears, refrigerators warm up, phones die, and people begin trying to power too many things at the same time.
Overloading Small Systems
Many people buy a small battery station expecting it to power refrigerators, fans, microwaves, lights, and multiple devices at once.
Ignoring Fuel Usage
Generators become much less useful once fuel stations lose power or fuel lines begin forming during longer outages.
No Power Priority Plan
Backup power disappears quickly when every device in the house gets treated like an emergency.
Forgetting Summer Heat
Refrigerators cycle harder, fans run longer, and battery systems drain faster during extreme summer temperatures.
The Better Strategy
The most reliable blackout setups usually layer multiple systems together: portable batteries for communication and lighting, solar charging for extended outages, fuel-based generators for refrigeration and heavy loads, and low-power devices that reduce overall energy demand.
Recommended Backup Power Sizes
300–800Wh
Best for phones, radios, headlamps, lanterns, and small USB devices.
Good for: short outages and basic emergency charging.
1,000–2,500Wh
Best for fans, CPAP, lights, phones, router, radios, and limited appliance use.
Good for: apartment and family blackout setups.
3,000–5,000Wh
Best for refrigeration, freezer support, medical devices, and longer outages.
Good for: serious blackout food protection.
5,000Wh+
Best for larger homes, sump pumps, refrigeration, fans, and layered backup systems.
Good for: generator or expandable solar generator setups.
Anyone planning for outages longer than a few days should also review fuel storage, water storage, and emergency communication planning because backup power alone does not solve long-term blackout problems.
Build a Complete Blackout Power Plan
Backup power is only one part of blackout readiness. Use these related guides to build a complete system for food, water, communication, lighting, and long-term grid-down planning.
