← all tools

The mAh on the box is not what you get.

A power bank loses about a third of its rated capacity to voltage conversion, so a 20,000mAh brick really delivers around 48Wh. This ranks by cost per usable Wh, the honest number, with the fast charge output and weight beside it. Sort for value, filter for laptop charging, done.

Prices reviewed 11 July 2026. Charger prices swing on sales, so check the live listing before buying.

Need serious backup instead? See the power station and solar panel rankings.

Search
Brand
Capacity
Output
Max price
Currency

Power bank Rated mAh Usable Wh Max output Weight Price $/usable Wh
How the ranking works. The headline metric is dollars per usable Wh, which is the honest value number. The rated mAh is measured at the cell voltage of 3.7V, but charging your devices loses roughly a third of that to conversion, so we compute the real delivered energy (about 65 percent of the paper figure) and divide the price by it. We also show the max output in watts, which decides whether it can fast charge a phone (20W+), a thin laptop (65W+) or a big laptop (100W+), plus the weight for travel. Sort by dollars per usable Wh for raw value, or filter by output if you need to charge a laptop. Prices are USD, converted live to your currency, and reviewed regularly.

Common questions

Why does it not charge my phone the full number of times?

The mAh is rated at 3.7V, but your phone charges at 5V or more and conversion loses energy as heat. You get about 60 to 70 percent out, so a 20,000mAh bank delivers roughly 48Wh. We show that real figure.

What size do I need?

10,000mAh gives a phone ~2 charges and stays pocketable. 20,000mAh covers phone plus tablet or a long trip. For a laptop, 20,000mAh+ with 65W+ output, 100W for a big laptop.

Can it charge a laptop?

Yes with enough capacity and a fast USB-C PD output. 20,000mAh+ and 65W for a thin laptop, 100W+ for full size. Filter by high output.

Best value power bank?

On $/usable Wh, plain 20,000mAh banks from value brands like INIU and Baseus are hard to beat, often half the cost per Wh of a premium unit. You pay extra for fast charge, magnetic wireless, a screen or slimness.