Xiaomi UltraThin Magnetic Power Bank Review: Is 6mm Too Thin?

Most magnetic power banks share the same problem: they're convenient in theory but bulky enough in practice that they end up in a drawer instead of on your phone. Xiaomi's UltraThin Magnetic Power Bank was built specifically to solve that a 5,000mAh battery packed into a body just 6mm thick, thin enough that reviewers consistently describe it as feeling like part of the phone rather than an add-on.

We looked at the engineering behind that thinness, real charging test results from independent reviewers, and where the design trade-offs show up, to see whether it's actually worth carrying daily.

Quick Verdict

The Xiaomi UltraThin Magnetic Power Bank delivers on its core promise it's genuinely thinner and lighter than any magnetic power bank most reviewers have tested, and that changes how likely you are to actually keep it attached to your phone. The trade-off is capacity: at 5,000mAh (roughly 3,000mAh of usable output after conversion losses), it's a top-up device, not an all-day charger. For most people who just need to get through the back half of a long day, that's a fair trade. If you regularly need a full overnight recharge or multiple full charges, look at Xiaomi's newer 10,000mAh version instead.

What Makes It Different: Silicon-Carbon Battery Tech

The reason Xiaomi can fit a 5,000mAh cell into a 6mm body comes down to battery chemistry rather than clever case design. The power bank uses a silicon-carbon battery with 16% silicon content, which delivers higher energy density than a conventional lithium-ion cell meaning more capacity in a thinner, lighter package. It's the same underlying approach that's let phone makers pack bigger batteries into slimmer phones over the past couple of years, now applied to a power bank.

Key Specs

Real-World Charging Performance

Specs on paper are one thing here's what independent testing actually showed:

• On a Samsung Galaxy S25 Ultra: Starting at 20% battery, wired USB-C charging reached 45% in 20 minutes, and fully depleted the power bank while taking the phone to 93% delivering approximately 3,650mAh of usable power out of its rated 5,000mAh capacity
• On an iPhone 17 Pro Max: Testing showed roughly 60-70% of a full charge added before the power bank was depleted
• Wireless charging speed varies by device. The full 15W wireless speed is currently limited to Xiaomi's own 17 series phones iPhones and other brands charge wirelessly at up to 7.5W, noticeably slower

The gap between rated capacity (5,000mAh) and real usable output (roughly 3,000-3,650mAh) isn't unique to Xiaomi it's normal across power banks due to voltage conversion losses but it's worth setting expectations accordingly rather than assuming you'll get a full 5,000mAh of charge.

Pros and Cons

What works well:

• Genuinely class-leading thinness and weight noticeably less likely to shift out of magnetic alignment compared to bulkier competitors
• Supports charging two devices simultaneously (one wired, one wireless)
• 22.5W wired charging is a real fast-charge speed, not just a marketing number
• Ten layers of safety protection, including overcharge and short-circuit protection
• Broad device compatibility across recent Xiaomi, iPhone, Samsung, and Pixel flagships

Where it falls short:

• Small usable capacity relative to price if raw capacity-per-dollar is your priority, larger conventional power banks cost less per mAh
• Full 15W wireless speed is currently Xiaomi-exclusive; other brands top out at 7.5W wirelessly
• Gets noticeably warm during use, since the metal shell doubles as a heatsink
• No charging cable included in the box in most regions

Compatibility

Official compatibility spans a wide range of recent flagships: Xiaomi 12 through 15 series, iPhone 12 through 17 series, Samsung Galaxy S23 Ultra through S25, and Google Pixel 9 and 10 series. Magnetic alignment (Qi2-based) works across all of these, though as noted, only Xiaomi's own 17 series currently unlocks the full 15W wireless speed.

There's Now a 10,000mAh Version

For anyone who wants meaningfully more capacity and is willing to trade away some of the ultra-thin form factor, Xiaomi has since launched a larger UltraThin model:

• 13.2mm thick (versus 6mm on the original) still notably thinner than most conventional 10,000mAh power banks, which typically run 15-18mm
• 195g weight, roughly double the original
• Up to 20W wireless and 45W wired charging a meaningful speed upgrade alongside the capacity increase
• Uses two 5,000mAh cells with the same silicon-carbon technology

As of this review, the 10,000mAh version is rolling out through Xiaomi's crowdfunding channel in China first, with a broader international launch expected later in 2026, following the same rollout pattern as the original 5,000mAh model.

Who Should Buy This

Good fit if you:

• Want a power bank slim enough that you'll actually keep it attached to your phone daily
• Mainly need a top-up (getting through a long afternoon or evening) rather than a full overnight recharge
• Own a recent Xiaomi, iPhone, Samsung, or Pixel flagship
• Value dual wired + wireless charging in one compact device

Consider alternatives if you:

• Need maximum capacity per dollar and don't mind extra bulk
• Own an iPhone or non-Xiaomi phone and specifically want full 15W+ wireless speeds
• Travel frequently and want a single power bank for multiple full phone charges the 10,000mAh version or a conventional larger power bank fits better here

Frequently Asked Questions

Does the Xiaomi UltraThin Power Bank really deliver 5,000mAh of charge? Not quite real-world testing shows roughly 3,000-3,650mAh of usable output due to normal conversion losses between the battery cell and your phone. This is standard across power banks generally, not specific to this model.

Will it charge my iPhone at full 15W wirelessly? No. The full 15W wireless speed is currently limited to Xiaomi's own 17 series. iPhones and other brands charge wirelessly at up to 7.5W through this power bank.

Is the 5,000mAh or 10,000mAh version better for me? If slimness and daily carry are your priority and you mainly need a partial top-up, the 5,000mAh (6mm) original is the better fit. If you need closer to a full charge or two, the 10,000mAh version trades some thinness for meaningfully more capacity and faster charging speeds.

The Bottom Line

The Xiaomi UltraThin Magnetic Power Bank succeeds at exactly what it set out to do: make a magnetic power bank thin and light enough that you'll actually use it, not just own it. The capacity trade-off is real, and iPhone or non-Xiaomi users won't get the full wireless speed, but as a slim daily-carry top-up device, it delivers on its core promise better than most magnetic power banks reviewers have tested.