The biggest mistake first-time buyers make is buying a power station that is too small (or too large) for their needs. This guide helps you calculate the right size.
The Simple Formula
Watt-hours needed = Device wattage x Hours of use
Add up all your devices, and you have your minimum capacity requirement. Then add a 20% buffer for efficiency losses (inverter conversion, cable resistance, battery degradation).
Common Device Power Draws
| Device | Wattage | 4 Hours Use | 8 Hours Use | |--------|---------|------------|------------| | Smartphone charger | 20W | 80Wh | 160Wh | | Laptop | 60W | 240Wh | 480Wh | | Wi-Fi router | 15W | 60Wh | 120Wh | | LED light bulb | 10W | 40Wh | 80Wh | | Portable fan | 40W | 160Wh | 320Wh | | Mini-fridge | 60W avg | 240Wh | 480Wh | | Full-size fridge | 150W avg | 600Wh | 1,200Wh | | CPAP machine | 40W | 160Wh | 320Wh | | TV (50 inch) | 110W | 440Wh | 880Wh | | Electric blanket | 200W | 800Wh | 1,600Wh | | Coffee maker | 1,000W | 50Wh (3 min) | 50Wh | | Microwave | 1,000W | 100Wh (6 min) | 100Wh |
Scenario Calculations
Weekend Camping (2 nights)
| Device | Wattage | Hours/Day | 2-Day Total | |--------|---------|-----------|-------------| | Phone charging (x2) | 40W | 2 hrs | 160Wh | | LED camp lights | 20W | 6 hrs | 240Wh | | Portable fan | 40W | 8 hrs (night) | 640Wh | | Mini-fridge | 60W | 24 hrs | 2,880Wh |
Total: 3,920Wh with fridge, or 1,040Wh without.
With the 20% buffer: 4,700Wh with fridge, 1,250Wh without.
Recommendation without fridge: EcoFlow Delta 3 Plus (1,024Wh) or Bluetti AC180 (1,152Wh)
Home Power Outage (8 hours)
| Device | Wattage | Hours | Total | |--------|---------|-------|-------| | Fridge | 150W avg | 8 hrs | 1,200Wh | | Wi-Fi router | 15W | 8 hrs | 120Wh | | Phone charging (x3) | 60W | 3 hrs | 180Wh | | LED lights (3 bulbs) | 30W | 8 hrs | 240Wh |
Total: 1,740Wh. With buffer: 2,088Wh.
Recommendation: Bluetti AC200L (2,048Wh) or Jackery Explorer 2000 v2 (2,042Wh)
Day Trip / Remote Work
| Device | Wattage | Hours | Total | |--------|---------|-------|-------| | Laptop | 60W | 6 hrs | 360Wh | | Phone | 20W | 1 hr | 20Wh | | Portable speaker | 10W | 4 hrs | 40Wh |
Total: 420Wh. With buffer: 504Wh.
Recommendation: Jackery Explorer 600 Plus (632Wh) or Bluetti AC70 (768Wh)
Quick Sizing Guide
| Your Need | Minimum Capacity | Recommended Range | |-----------|-----------------|-------------------| | Phone + laptop only | 200-300Wh | EcoFlow River 3 | | Light camping (no fridge) | 500-800Wh | Bluetti AC70 | | Camping with fridge | 1,000-1,500Wh | EcoFlow Delta 3 Plus | | Home backup (4-6 hrs) | 1,000-1,500Wh | Bluetti AC180 | | Home backup (8-12 hrs) | 2,000-4,000Wh | Bluetti AC200L | | Whole-home backup | 4,000Wh+ | EcoFlow Delta Pro 3 |
Pro Tips
- Round up, not down. If your calculation shows 900Wh, buy at least a 1,000Wh station.
- Fridges are the big variable. With a fridge, you need at least double the capacity versus without.
- Solar extends runtime. A 200W panel adds 800-1,200Wh per sunny day, effectively doubling a 1,000Wh station's daily capacity.
- Efficiency losses are real. AC inverter conversion wastes 10-15% of stored energy. USB output is more efficient.
Related reading: See our best power stations under $500 and best power stations under $1,000 for specific recommendations at every budget.