A LITTLE PREPARATION. A LOT LESS GUESSWORK.
Keep the essentials.
Skip the guesswork.
How much battery do you actually need? Build a plan for the things that matter, then see what you can leave switched off.
Build my power plan ↗01 / BUILD YOUR PLAN
What needs to stay on?
Start with an example. Replace the numbers with your own.
Plan for an outage
Choose the time you want to cover.
Example wattages are placeholders, not measurements. “Use” means the percentage of your outage window drawing the entered watts. Refrigerator annual energy already includes cycling.
Adjust losses & reserve ↓
These are editable planning assumptions, not measured specifications for the models below. AC inverter stays on for the whole window. No charging, solar input or temperature model is included.
Capacity and output are two different checks. Watt-hours (Wh) determine how much energy you can store. Watts (W) determine what you can run at once. A big battery can still fail to start a motor.
See the math ↗02 / CHECK A BATTERY
How long would it last?
WITH YOUR CURRENT PLAN
— hours
Average-use extrapolation; cycling and timing make short-outage results less reliable. The higher-demand scenario uses 25% more appliance energy and efficiency 10 percentage points lower (minimum 50%). It is a sensitivity check, not a confidence interval.
WHERE YOUR ENERGY GOES
Compare a few reference models.
US model specifications. Not a complete market comparison or hands-on review.
Manufacturer links below are ordinary links. We currently earn no commission from them.
Model specifications checked October 26, 2026. Availability and price are on the retailer’s site. Matching numbers alone does not confirm motor startup, waveform, port, voltage or UPS compatibility. Always check the exact model manual. References expire after 90 days without review.
03 / FIELD NOTES
A better plan starts with better numbers.
Start with the yellow label.
Use annual refrigerator energy without pretending the compressor runs all day.
Read the guide ↗02 — STAY CONNECTEDYour router isn’t the whole story.
Include the modem or ONT, and understand what a battery cannot fix.
Read the guide ↗03 — BUY WITH A PLANThe two numbers on the box.
Separate battery size from running power, startup demand and boost modes.
Read the guide ↗A FEW GOOD QUESTIONS
Before you buy anything.
Does this replace measuring my appliances?
No. Sample loads are editable starting points. Use a suitable plug-in energy meter for ordinary plug-in appliances and follow its rating and instructions. EnergyGuide annual usage can estimate a refrigerator’s average energy, but does not reveal starting watts.
Why can’t the tool confirm my refrigerator will start?
Starting current, surge duration and inverter behavior vary. Missing startup measurements are flagged. Even supplied figures require a check against the manufacturer’s motor-load guidance. This tool does not design building wiring or power medical or life-safety equipment.
Does it include solar panels or recharging?
No. This is a single-battery, no-recharge scenario. Sunlight, panel placement, weather, input limits and charge scheduling need a separate plan.
Where does my plan go?
Calculations and saved plans stay in this browser. Copying a plan link embeds appliance settings in its URL fragment so anyone you send it to can open it. Do not include personal details in appliance names. The hosting provider may process ordinary access logs.
Are you selling the batteries?
No. Any purchase is made directly with the retailer, which handles shipping, returns, warranty and product support. Outage Atlas provides a self-service planning tool. We have not physically tested the listed products.