Compact CampingHow many mAh do you need for backpacking?
Power bank capacity numbers are more marketing than promise. A 10,000 mAh bank does not put 10,000 mAh into your phone, and knowing the real number changes what size is actually worth carrying.
Why the printed number lies a little
Converting a power bank's stored charge into your phone's specific voltage loses energy as heat, typically around 20–30% of the rated capacity. A "10,000 mAh" bank realistically delivers something closer to 6,500–8,000 mAh of usable charge once that conversion loss is accounted for. Against a typical phone battery of 3,000–4,500 mAh, that works out to a little over two full charges from a 10,000 mAh bank, not the 2.5–3 the printed number might suggest.
Sizing to your actual trip
A weekend trip with your phone in airplane mode most of the time rarely drains more than one charge, which a smaller, lighter bank easily covers. A week or longer, or heavy use for photos, offline maps, or a satellite communicator like our top navigation pick, adds up fast — plan on one full phone charge per two to three days of moderate use, more if you're also topping up a GPS or headlamp. Our top pick, the Nitecore NB10000 Gen4, weighs about 140 g for that 10,000 mAh capacity, a reasonable weight-to-charge ratio for most multi-day trips; our budget pick, the Anker PowerCore 10000, covers the same capacity class at a lower price.
When solar earns its weight
A solar panel like our solar pick, the BigBlue SolarPowa 28W at around 490 g, only makes sense once a trip runs long enough that no fixed-capacity power bank could realistically cover it, since panel output depends entirely on sun exposure and is genuinely slow compared to a wall charger. For anything under about a week, a larger power bank alone is usually lighter and more reliable than adding solar to the kit. Solar earns its weight on trips measured in weeks, not days, where recharging is the only way to keep going at all.
What's actually drawing power
A phone in airplane mode with occasional photos is a light draw. A satellite communicator, GPS, or headlamp charging alongside it adds up — if you're carrying our navigation picks too, budget extra capacity for them specifically, since a dead communicator defeats the point of carrying one.
Verdict
For a weekend, a compact 10,000 mAh bank like the Nitecore NB10000 Gen4 or Anker PowerCore 10000 is plenty once you account for the real, efficiency-adjusted charge it delivers. For week-plus trips or multiple devices drawing from the same bank, either size up meaningfully or add a solar panel — don't rely on the printed mAh number to tell you which.