How Many Watts!
Some links on this site may earn us a commission. It never changes which units we show. How that works.
Method

How we choose

The site exists to help you work out what you need, then show every unit that fits, not to push a particular brand.

1. We work out what you need

From your list we calculate daily energy use, peak power draw and, if you add solar, the panels you need. The working is shown under every result. We use rough planning figures for efficiency (85% inverter, 90% usable battery) and UK sun hours (about 4 in summer, 2.5 in spring and autumn, 1 in winter).

2. We list every unit that fits and is in stock

Any unit in our list with enough capacity and output is a candidate. Brand plays no part. At the moment the list covers 36 units from EcoFlow, Jackery, Anker SOLIX and Bluetti.

We only recommend a unit if it is in stock at a retailer we link to, so you don't click through to a sold-out page. Stock changes daily, so we check it regularly and always say when. A unit that is sold out everywhere we link to is taken out of the results until it returns.

3. We show the best on each measure

  • Smallest that fits: the lowest capacity that meets your needs.
  • Lightest to carry: lowest weight including any panels needed.
  • Most Wh per kg: the most capacity for its weight.
  • Fastest solar charging: the highest solar input, when you plan to use solar.
  • Most spare output: the highest output, when you're running on battery alone.

One unit can win more than one. We don't pick prices as a measure, because prices change daily and we won't show a price we haven't verified.

Keeping it impartial

  • Commission rates aren't stored in our data, so they can't change what the tool shows.
  • Where a unit is sold by more than one seller, we'll show the links side by side with equal weight.
  • If a brand sends us a unit for free, we'll say so on any page about it.
  • We'll say plainly whether a page is based on specs and published reviews or on units we've tested.

Where the data comes from

Specs come from retailer pages and spec databases, not directly from maker spec sheets, and some sources disagree. We use the cautious figure and note it on the card. We last checked on 10 October 2026. If you spot an error, tell us and we'll correct it.