Original analysis
How much of the box rating do you actually get?
As of July 23, 2026, across the 27 power stations we track, independent testers measured a median of 86% of the box rating, from 75% (Anker 521) to 93% (EcoFlow DELTA Pro 3).
The capacity printed on the box is the energy stored in the battery. Inverter and conversion losses mean less reaches your appliances. We take the share testers measured from their own discharge tests; every number below is computed from the figures on our model pages, each cited to its source.
Median share
86%
Lowest
75%
Anker 521
Highest
93%
EcoFlow DELTA Pro 3
By brand
| Brand | Models | Lowest | Median | Highest |
|---|---|---|---|---|
| Anker SOLIX | 4 | 80% | 88% | 91% |
| Bluetti | 4 | 85% | 88% | 92% |
| Grecell | 1 | 87% | 87% | 87% |
| DJI | 1 | 86% | 86% | 86% |
| Jackery | 4 | 84% | 86% | 89% |
| EcoFlow | 10 | 80% | 85% | 93% |
| Goal Zero | 1 | 83% | 83% | 83% |
| Vtoman | 1 | 79% | 79% | 79% |
| Anker | 1 | 75% | 75% | 75% |
Most brands have only a few tested models, so read these as what testers found on those units, not as a verdict on a brand.
By size
| Box rating | Models | Lowest | Median | Highest |
|---|---|---|---|---|
| Up to 500 Wh | 4 | 75% | 83% | 89% |
| 501 to 1,500 Wh | 14 | 81% | 87% | 90% |
| Over 1,500 Wh | 9 | 79% | 85% | 93% |
By tester
| Source | Models | Lowest | Median | Highest |
|---|---|---|---|---|
| OutdoorGearLab | 13 | 75% | 85% | 93% |
| Outdoor Life | 7 | 79% | 87% | 90% |
| StorageReview | 7 | 80% | 88% | 92% |
- OutdoorGearLab: Full discharge at about 80% of the unit's rated output.
- Outdoor Life: Fresh-charge run of a ~380 W dehumidifier on an AC port.
- StorageReview: Lab discharge from 100% to 0%, usually at 300 to 350 W; some reviews don't state the load.
The load changes the result: units usually deliver a larger share at heavier loads and a smaller share at light ones. Compare numbers from the same tester more confidently than numbers across testers.
Every model, highest share first
Limits
- Each model has one measurement from one unit. Results can change with firmware, temperature and battery age.
- Testers use different loads, so the comparison across testers is rough. See the methodology.
- We only list models with a credible measured figure, so the sample is not every product on the market.
- Some tests are a year or more old. Each row shows its date.