Last updated: August 11, 2026
Amazon Associates Disclosure: As an Amazon Associate, OriginSelect earns from qualifying purchases. This guide uses planning calculations and published specifications; actual appliance consumption varies.
Quick Answer
For many households, approximately 1,000–1,500Wh of capacity with 1,500–2,000W of continuous output is a practical starting range for a refrigerator, internet equipment, lighting and device charging. Choose approximately 2,000–3,000Wh for longer runtime or a sump pump. A small 300–600Wh station is communications and lighting backup only.
Quick Size Guide
| Power-station size | Best suited to | Limitation |
|---|---|---|
| 250–300Wh | Phones, Wi-Fi, radio, LED lights | Too small for fridge or pump use |
| 500–800Wh | Communications, laptops, limited appliances | Refrigerator runtime may be short |
| 1,000–1,500Wh | Refrigerator, Wi-Fi, lights, essentials | Requires careful load management |
| 2,000–3,000Wh | Longer fridge backup, intermittent pump | Heavier and more expensive |
| 3,000Wh+ | Extended selected-load or expandable systems | May no longer be conveniently portable |
The Sizing Formula
Device energy (Wh) = running watts × hours of operation. Add every essential device, then apply a reserve: Suggested capacity = total required Wh ÷ 0.85 × 1.20. Dividing by 0.85 allows about 15% for conversion loss; multiplying by 1.20 adds a 20% reserve for cold conditions and ageing.
For cycling appliances like refrigerators, sump pumps and furnace blowers, calculate the total expected on-time rather than the entire outage duration. An 800W pump running 30 minutes during a 12-hour outage uses 800W × 0.5h = 400Wh — but the station still needs enough continuous and surge output to start it.
Worked Example: Refrigerator Plus Basic Essentials
| Device | Assumption | Energy |
|---|---|---|
| Refrigerator | 70W avg × 8h | 560Wh |
| Modem and Wi-Fi router | 20W × 8h | 160Wh |
| Two LED lights | 20W × 5h | 100Wh |
| Phones and electronics | Estimated total | 40Wh |
Total load energy: 860Wh. Applying the sizing allowance: 860Wh ÷ 0.85 × 1.20 ≈ 1,214Wh — pointing to a station in the 1,000–1,500Wh range.
Why a Space Heater Changes the Calculation
A standard portable space heater draws approximately 1,500W continuously. Four hours of use requires 6,000Wh — after allowances, approximately 8,471Wh, far beyond most portable units. A 1,024Wh station may provide only around 35 minutes of full-output heating. See our portable power station comparison for models by capacity class.
Continuous Output and Surge
After sizing capacity, add the running wattage of devices that may operate simultaneously (fridge 150W + sump pump 800W + router/lights 40W + laptop 65W = 1,055W). A 1,000W inverter would be undersized. Motors and compressors can also draw considerably more power for a short period when starting — check the appliance label or manual for surge requirements.
Real Amazon.ca Examples by Capacity
| Model | Capacity | Output | Role |
|---|---|---|---|
| EcoFlow RIVER 3 Plus | 286Wh | 600W | Wi-Fi, phones, lights |
| Anker SOLIX C1000 Gen 2 | 1,024Wh | 2,000W | General short-outage essentials |
| EcoFlow DELTA 3 Plus | 1,024Wh | 1,800W | Expandable starting system |
| Jackery Explorer 1000 v2 | 1,070Wh | 1,500W | Portable 1kWh alternative |
| BLUETTI Elite 200 V2 | 2,073.6Wh | 2,600W | Longer selected-load backup |
A Simple Pre-Purchase Worksheet
Write down every essential device, its running and startup wattage, estimated hours of use, total watt-hours required, maximum simultaneous running load, highest likely startup surge, and how the station will be stored and recharged. Consult an electrician for any hardwired equipment.
Frequently Asked Questions
Is a 1,000Wh power station enough for a refrigerator?
It may be enough for several hours or overnight, depending on the fridge's average consumption and startup surge. Measure your own appliance rather than relying on a universal claim.
Should I choose more capacity or more output?
Both, in the correct amounts. Capacity determines runtime; continuous and surge output determine whether connected equipment can actually operate.
Should I include a sump pump in winter calculations?
Yes, when snowmelt, rain or a thaw could cause it to operate. Use actual running and startup requirements.
Final Recommendation
Start by calculating needs around the 1,000–1,500Wh class with at least 1,500–2,000W of continuous output. Move into the 2,000–3,000Wh class for longer refrigerator runtime or intermittent sump-pump operation. Compare battery against fuel backup in our power station vs. generator guide.