How we calculate

Runtime

Runtime (h) = capacity (Wh) × 0.85 ÷ (load (W) + own draw, where the maker lists it)

Example: the Jackery Explorer 1000 v2 has 1,070 Wh. At 100 W: 1,070 × 0.85 ÷ 100 = 9.1 hours.

The 0.85 covers the energy lost when the station turns its battery into 120 V AC. Anker (guide) and Jackery (FAQ) use a similar factor. Where a maker publishes the station’s own power draw, as BLUETTI does in its manuals (Elite 30 V2 manual) and Anker does for the C2000 Gen 2, we add it to the load, as BLUETTI’s own runtime formula does. Other makers don’t publish it; every station draws some power itself, so at small loads their real runtimes are likely somewhat shorter than our figures. USB‑C and 12 V outputs skip most of that loss, so they run longer than our AC figures.

Fridges and freezers

A fridge’s compressor cycles on and off, so its label watts overstate what it uses over a day. We use yearly energy instead: kWh a year × 1,000 ÷ 8,760 hours. The average main (most-used) US fridge used 617 kWh in 2020 (EIA), which is 70.4 W averaged. For your own fridge, use the kWh on its yellow EnergyGuide label.

Start-up surge

Motors need more power for a moment when they start. Anker says some fridges need two to three times their running power (Anker); BLUETTI’s manual says some compressors need two to four times (BLUETTI). The calculator checks fridges and freezers at about 300 W running × 3 against the larger of each station’s listed surge and its continuous output. If a maker lists no surge rating, we say so instead of guessing.

Solar refill

Sun hours = Wh ÷ (0.75 × the lower of panel watts and the station’s solar input)

Panels rarely deliver their full rating, so we count 75% of it. That is our own assumption, not a maker figure, and it is on the optimistic side: clouds, heat, winter sun and charging losses add time. Where a maker publishes its own solar charge time, the station page shows it too.

Cold and battery age

The advanced calculator can take off 15% for cold weather and 10–20% for an older battery. Those are planning allowances, not measurements. Most stations here can’t charge below freezing; each station page shows the maker’s charging and running temperatures.

Where specs and prices come from

• Specs come from each maker’s US product page or manual, linked on every station page. Where a figure is missing there, the page says which other source we used (for one station, a retailer’s listing of the maker’s specs). When a product page and a manual disagree, we show both or say which we used.
• Prices are read from the makers’ own US stores and dated. Coupons and cart discounts aren’t included; the price at checkout applies.
• Device watts come from government data (EIA, ENERGY STAR, DOE), the device makers, university extension services, utilities, energy nonprofits such as NRDC and, where nothing better is published, generator makers’ wattage charts. Each is linked where it is used.
• We cover 16 stations from ALLPOWERS, Anker SOLIX, BLUETTI, EcoFlow and Jackery.

What we don’t do

• We don’t test products or claim to have used them.
• Rankings come only from the specs, the prices and your inputs. Some links pay us a commission and are marked “Paid link”; the math is the same either way. See how we make money.
• We don’t give wiring advice. Connecting to house circuits is a job for a licensed electrician.

Corrections

Spotted a wrong spec, price or formula? Email [email protected] and we’ll fix it and update the date.