Decision Lantern

Energy and power calculator

How many watt-hours do I need in a power station?

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People estimating a portable battery size from devices they already own. The decision this page isolates is narrow on purpose: estimate energy capacity and inverter requirements without selecting a product. Watt-hours and inverter watts are different limits. Size both before you compare a station.

Your load

Device 1

Sizing assumptions

Estimated minimum capacity

735 Wh

Device energy
520 Wh
Continuous output
65 W
Surge output
65 W

520 Wh ÷ 85% efficiency × 1.20 reserve = 735 Wh.

Example products for How many watt-hours do I need in a power station?

Real products that fit this planning category. Specs come from the manufacturer’s product page. These are examples, not rankings. The links are official product pages—not affiliate links yet.

Open a matching official example

Compare the official examples

The table below is a side-by-side of the official examples on this page. Columns are published facts—maker, planning class, and notes taken from the official page—not scores. EcoFlow RIVER 2, EcoFlow DELTA 2, and Jackery Explorer 1000 v2 are included so you can see how classes differ, then open the official page for the current specification.

Published facts for the example products on this page. Not a ranking.
ExampleMakerPlanning classesPublished notes
EcoFlow RIVER 2EcoFlowPower Station256 Wh; 300 W output
EcoFlow DELTA 2EcoFlowPower Station1024 Wh; 1800 W output
Jackery Explorer 1000 v2JackeryPower Station1070 Wh; 1500 W output

What to verify before you buy

Measurement notes

Measure: List every device you actually plan to run, not a wishlist. Use the nameplate watts on the brick or the product spec sheet. For phones and laptops, battery watt-hours printed on the pack are more honest than a charger’s peak watt rating. Time is the hours you need the device on, not the hours you own it.

Example: A 60 W laptop for 4 hours is 240 Wh, a 10 W router for 12 hours is 120 Wh, and a 40 W mini-fridge for 8 hours is 320 Wh. That is 680 Wh of load. At 85 percent inverter efficiency with a 20 percent reserve, plan around 960 Wh, not a 300 Wh picnic pack.

Avoid: People shop by “powers a fridge” marketing and ignore surge watts. Compressors and power tools draw several times their running watts at start. If the inverter cannot cover that spike, the station trips even when the watt-hour math looks fine.

How this estimate works

Add wattage multiplied by runtime and quantity, adjust for conversion efficiency, then add the selected reserve.

Energy is power over time: watts × hours = watt-hours. Capacity and inverter output are separate constraints, so the result reports both.

Know the limits

  • Actual runtime varies with temperature, battery age, inverter behavior, and manufacturer limits.
  • The estimate is not an electrical-safety assessment or an emergency-runtime guarantee.
  • Verify running and surge requirements against the device and power-station manuals.

Frequently asked questions

How does the portable power station sizing work?

It converts the published inputs on this page into a planning class using a published rule. Add wattage multiplied by runtime and quantity, adjust for conversion efficiency, then add the selected reserve. The headline is a class such as Power Station, not a vendor ranking.

Is EcoFlow RIVER 2 better than EcoFlow DELTA 2?

This page does not rank EcoFlow RIVER 2, EcoFlow DELTA 2, and Jackery Explorer 1000 v2. EcoFlow RIVER 2 and EcoFlow DELTA 2 are listed because they are real products with official pages that map to different or overlapping classes. The useful question is which class matches your inputs.

Do the product links earn Decision Lantern a commission?

Not on this page. The example links go to official manufacturer or service pages. If compensated links are added later, the disclosure on this page will say so in plain language.

Sources

  1. Basics of Electricity, Energy, National Renewable Energy Laboratory. Retrieved .

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