Press and media
RuntimeMath works out how long portable power stations run everyday devices, from the makers’ published specs. It covers 18 stations from 5 brands sold in the US, with prices read from the makers’ US stores (Oct 24, 2026, unless a page gives another date). It is run by Kristoffer Myklebust (Kristoffer Myklebust ENK, Norway).
Numbers you can cite
- An average US fridge (70.4 W averaged, from EIA’s 617 kWh a year) runs about 10.8–13.9 hours on the 5 stations of 1,024–1,152 Wh we list. Fridge guide.
- A ResMed AirSense 10 CPAP with its humidifier on (22 W) runs about 3.3–5.6 nights of 8 hours on the same stations. CPAP guide.
- A 1,500 W space heater empties a 1,000 Wh station in about 34 minutes. Heater guide.
- Sizing rule: watts × hours ÷ 0.85. A fridge for a day needs about 1,990 Wh of capacity. Sizing guide.
Every figure is our math from published specs: capacity × 0.85 ÷ load, with the station’s own draw added where the maker lists it. We don’t test products. The formulas and sources are on How we calculate, and every station in one line is in llms-full.txt.
Using our numbers
- Please name RuntimeMath and link to the page the number comes from.
- Bloggers can add the free calculator to a page: see Embed the calculator.
- Logo: logo.png. Share image: og.png.
Contact
Questions about runtimes, sizing for outages, CPAP or RV use, or solar recharge times: [email protected].