How we score
Every model here gets a 0–10 score built from official specs — the same formula, the same inputs, for every single unit. No mystery, no fine print: this page is the whole method, and you can check our math yourself.
Portable power stations
The formula
Here's how it works. Each metric is min-max normalized across the 13 models
we track: (value − min) / (max − min). For weight we flip it, so a lighter unit
scores higher. Then we add it all up and multiply by ten:
score = 10 × (0.25·capacity + 0.25·AC output + 0.20·cycle life + 0.15·portability + 0.15·solar input)
| Metric | Weight | Direction | Why it matters |
|---|---|---|---|
| Battery capacity (Wh) | 25% | Higher is better | How long it runs your gear. |
| AC output (W) | 25% | Higher is better | What it can power at all. |
| Cycle life (rated cycles) | 20% | Higher is better | How many years before the battery fades. |
| Portability (weight, lbs) | 15% | Lower is better | Whether you'll actually take it along. |
| Max solar input (W) | 15% | Higher is better | How fast it refills off-grid. |
One detail worth knowing: cycle life is parsed as the leading integer of the manufacturer's rating (e.g. "3,000+ cycles to 80%" → 3000). And if a model is missing a metric, it scores zero on that term — the formula never guesses.
Worked example
Run the numbers yourself
Don't take our word for it — here's the current top scorer, EcoFlow DELTA Pro 3, with every step shown:
| Metric | Raw value | Normalized | Weight | Points |
|---|---|---|---|---|
| Battery capacity | 4,096 Wh | 1.000 | 25% | 2.50 |
| AC output | 4,000 W | 0.649 | 25% | 1.62 |
| Cycle life | 4,000 cycles to 80% | 1.000 | 20% | 2.00 |
| Portability (weight) | 113.5 lbs | 0.149 | 15% | 0.22 |
| Max solar input | 2,600 W | 1.000 | 15% | 1.50 |
| Total | 7.8 |
Other categories
Same method, different dials
Our other 18 categories — solar panels to Bluetooth speakers — run on the same min-max method, just with metrics and weights tuned to each category. If a model is missing a spec, we score it on the specs it does have and rescale the remaining weights to sum to one. Missing is never treated as zero.
| Category | Weights | |
|---|---|---|
| Portable Solar Panels | rated output 30% · conversion efficiency 25% · portability (weight) 25% · weatherproofing 20% | open comparison ↗ |
| Camping Fridges | capacity 25% · power draw 25% · portability (weight) 20% · dual zone 15% · battery protection 15% | open comparison ↗ |
| Inverter Generators | rated output 25% · noise 25% · runtime 20% · portability (weight) 15% · CO safety shutoff 15% | open comparison ↗ |
| Portable Projectors | brightness 30% · battery runtime 25% · portability (weight) 20% · speaker output 15% · throw ratio 10% | open comparison ↗ |
| Smart Kitchen Gadgets | review volume 35% · estimated monthly sales 35% · buyer rating 30% | open comparison ↗ |
| Countertop Ice Makers | daily output 30% · estimated monthly sales 25% · review volume 25% · buyer rating 20% | open comparison ↗ |
| Home Air Purifiers | room coverage 30% · estimated monthly sales 25% · review volume 25% · buyer rating 20% | open comparison ↗ |
| Robot Vacuums | rated suction 30% · estimated monthly sales 25% · review volume 25% · buyer rating 20% | open comparison ↗ |
| Hair Styling Tech | light weight 30% · estimated monthly sales 25% · review volume 25% · buyer rating 20% | open comparison ↗ |
| Desktop 3D Printers | rated print speed 30% · estimated monthly sales 25% · review volume 25% · buyer rating 20% | open comparison ↗ |
| Espresso Machines | review volume 35% · estimated monthly sales 35% · buyer rating 30% | open comparison ↗ |
| Smart Bird Feeders | video resolution 20% · buyer rating 20% · AI species database 15% · review volume 15% · camera count 10% · estimated monthly sales 10% · seed capacity 5% · battery capacity 5% | open comparison ↗ |
| Gaming Headsets | driver size 30% · battery life 25% · weight 25% · high-frequency reach 20% | open comparison ↗ |
| Gaming Mice | weight 30% · polling rate 25% · sensor resolution 25% · battery life 20% | open comparison ↗ |
| Mechanical Keyboards | battery life 30% · polling rate 25% · hot-swap support 25% · connectivity 20% | open comparison ↗ |
| Noise-Canceling Headphones | battery life 30% · weight 25% · driver size 20% · Bluetooth version 15% · hi-res codec 10% | open comparison ↗ |
| Gaming Handhelds | battery capacity 25% · weight 20% · refresh rate 20% · storage 20% · screen resolution 15% | open comparison ↗ |
| Bluetooth Speakers | battery life 30% · ingress protection 20% · weight 20% · Bluetooth version 15% · rated output 15% | open comparison ↗ |
| Wireless Microphones | transmitter weight 25% · transmitter battery 25% · transmission range 20% · onboard recording 15% · total battery 15% | open comparison ↗ |
Where the numbers come from
Every spec on this site comes from the manufacturer's official product page — never from retailer listings, reviews, or forums. Each product page links to the exact source its numbers came from, so every figure is one click away from verifiable.
How often we update
We re-verify specs against the official pages once a month. The moment a data point changes — or a model joins or leaves the list — the scores are recomputed that same day. The footer of every page shows the last data update (currently 2026-10-05).
What we don't do
To be straight with you: we don't lab-test. We don't tear units down, run load banks, or claim hands-on time. We don't show prices — there's no live price feed yet, so prices and availability are checked on Amazon. And we don't sell placement: no brand can pay to move a score, because the formula only reads specs.
How we make money
As an Amazon Associate we earn from qualifying purchases made through links on this site. The commission comes out of Amazon's pocket, not yours — and it never enters the formula. The math only sees specs.
Spotted an error?
If a number here ever differs from the official brand page, the official page wins — and verified errors get fixed in the next update cycle. To flag one, email the corrections address published with our newsletter signup (launching soon). Until then, the official sources linked from every product page are the authoritative record.
Thanks for caring about the math — that's exactly why we publish it.