Best Compact Power Banks: Anker Nano 10K vs UGREEN MagFlow Qi2 vs Anker 5K MagGo Slim

By Alexandre Mayden · Updated October 9, 2026 · How we review

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Quick answer: it’s a tie at the top (4.0/5). The Anker Nano Power Bank 10K is the best value: 10,000 mAh, 30W and a built-in USB-C cable for around US$30. If you have a recent iPhone and want to charge without cables, the UGREEN MagFlow 10K adds 25W magnetic wireless charging — at a higher price.

A compact power bank is about balance: enough capacity for a full phone top-up or two, fast enough to make a short break count, and small enough that you actually carry it. Built-in cables and magnetic wireless charging have changed what “compact” means. We compared three popular pocket-sized power banks on their published specifications: Anker’s Nano 10K, UGREEN’s MagFlow 10K with Qi2 25W, and Anker’s ultra-thin Nano 5K MagGo Slim.

What matters when choosing a compact power bank

Rated capacity isn’t what reaches your phone. A power bank’s capacity is measured at its battery cells’ voltage. Converting that to USB voltage, plus heat losses, means a phone typically receives around two-thirds of the rated figure — one independent test measured about 6,800 mAh delivered from a 10,000 mAh Anker Nano. As a rough guide, 10,000 mAh refills most phones about one and a half times; 5,000 mAh gives roughly one top-up to 70–100% depending on the phone.

Wired is faster and more efficient than wireless. Magnetic wireless charging is convenient — no cable, phone stays usable — but some energy is lost as heat. Use the cable when you need speed or every last percent.

25W wireless needs a compatible phone. Qi2 25W (Qi2.2) speeds currently apply to recent iPhones (iPhone 16 and 17 families on iOS 26, excluding the 16e). Other magnetic-compatible phones charge at up to 15W.

Flying? Airlines generally allow power banks under 100 Wh in hand luggage (never in checked bags). All three here are well under that limit, but check your airline’s rules.

Specifications side by side

How we scored them

Each power bank is rated from 1 to 5 on six comparison points, based on how its published specification compares with the other two. The overall score is the average. Read our full method.

1. Anker Nano Power Bank 10K — best value (4.0/5)

Anker’s Nano 10K packs 10,000 mAh and 30W fast charging into a 104 × 52.3 × 26 mm block weighing 215 g. Its built-in USB-C cable means you’re never stuck without one, and a separate USB-C port and a USB-A port (up to 22.5W) let you charge up to three devices at once — though combined output drops to 24W when several are connected. Independent testing found it consistently delivers its 30W, taking an iPhone from empty to 50% in about half an hour.

It has no wireless charging at all, which is the only reason it doesn’t win outright. It’s also not designed for laptops — 30W is enough for phones, earbuds and small tablets.

Not for you if: you want to charge your phone magnetically, cable-free.

2. UGREEN MagFlow 10K Qi2 25W — best for iPhone (4.0/5)

UGREEN’s MagFlow ties on score by doing everything: 10,000 mAh, magnetic wireless charging at up to 25W for compatible iPhones, a built-in USB-C cable rated for 30W two-way fast charging (it also works as a carry strap), plus a second USB-C port. UGREEN says it can power three devices at once and gives nearly two full iPhone charges, and retailers list a display showing the remaining charge.

The cost is size and price: at 110.8 × 70 × 21 mm and 254 g (figures from retailer listings), it’s the bulkiest here, and its £79.99 UK price is more than double the Anker Nano’s typical price. Note that the newer MagFlow Pro is a different, more expensive model.

Not for you if: you mainly charge with a cable, or price matters most.

3. Anker Nano 5K MagGo Slim — thinnest (3.3/5)

Anker’s Nano 5K MagGo Slim is the one you’ll forget is attached: Anker quotes a 7.6 mm slim profile (its spec sheet lists 8.6 mm at the thickest point) and retailers list it at about 130 g. It snaps onto a MagSafe-compatible iPhone and charges at up to 15W wirelessly, or 20W over USB-C, and Anker says it keeps its back below 38°C with graphene cooling.

Half the capacity of the other two means roughly one phone top-up rather than one and a half, and with no built-in cable, wired charging needs your own. It scores lowest on paper but is the most pocketable by far.

Not for you if: you need a full day of extra battery, or want 25W wireless.

Which one should you buy?

• Best value, any phone: Anker Nano 10K.
• Recent iPhone and you hate cables: UGREEN MagFlow 10K.
• You want it on your phone all day without noticing: Anker Nano 5K MagGo Slim.
• Android phone: Anker Nano 10K — the wireless models are designed around magnetic iPhones.

Frequently asked questions

How many times will a 10,000 mAh power bank charge my phone?

Usually about one and a half full charges for a typical smartphone, because roughly a third of the rated capacity is lost to voltage conversion and heat.

Can I take these power banks on a plane?

Generally yes, in hand luggage only. Most airlines allow power banks under 100 Wh without approval, and all three here are far below that. Rules vary, so check with your airline.

Does magnetic wireless charging work with Android phones?

Only with phones that support Qi2 magnets or with a magnetic case. Most Android phones don’t have built-in magnets, so a wired power bank is the simpler choice.

Is wireless charging bad for my battery?

Wireless charging creates more heat than wired charging, and heat is what ages batteries. These power banks manage temperature, but if battery health is a priority, use the cable when you can.

Our verdict

For most people, the Anker Nano 10K is the smartest buy: fast, compact, with a cable you can’t forget, at a low price. If you own a recent iPhone and value cable-free charging, the UGREEN MagFlow 10K is worth the extra. Choose the Anker Nano 5K MagGo Slim when thinness matters more than capacity.

Sources

• Anker — Nano Power Bank (10K, 30W, built-in USB-C cable) specifications
• UGREEN UK — MagFlow Magnetic Power Bank 10000mAh 25W
• Digitec — UGREEN MagFlow 10000 mAh specifications (size, weight)
• Anker UK — Nano Power Bank (5K, MagGo, Slim)
• Engadget — Best power banks (independent testing)

Specifications checked on 9 October 2026. Prices vary by country and retailer.