How to Choose a Power Bank: mAh, Ports and What Actually Matters for Travel (2026)

The Expensive Mistake Everyone Makes Once

You buy the biggest power bank you can find — 26,800mAh, feels like a brick, nearly triggers a weight fee — and then notice it has two USB-A ports that output 5W each. Your phone spends an hour on it and gains 20%. Meanwhile your travel partner's slim 10,000mAh bank has a 30W USB-C port and fully charges her phone in under an hour.

The capacity isn't wrong; the specs around it are. Here's how to avoid buying the number instead of the power bank you actually need.

mAh: What It Means and When to Stop Caring

mAh (milliamp-hours) is how much energy a bank can store. Higher numbers mean more charges — but there's a catch most listings skip: every power bank loses 20–30% of its rated capacity to heat and conversion, so a 10,000mAh bank in practice delivers closer to 7,000–8,000mAh to your device.

There's also a hard travel limit: Australian airlines (and most international carriers) cap power banks at 100Wh in carry-on — no exceptions in the hold. At 3.7V, that's roughly 27,000mAh. Banks above that can't fly.

Use case	Starting point	Notes
Day bag / commute	5,000–10,000mAh	Pocket-sized; fine for one full phone charge
Weekend trip	10,000–15,000mAh	Handles phone + earbuds + smart watch
Long-haul flight	20,000–26,800mAh	Check your airline — some cap at 20,000mAh
Maro tip	10,000mAh for most people	Lighter, easier to carry every day

Output Wattage: The Spec That Actually Matters

This is where most buyers get burned. A 20,000mAh bank with 5W output will take six to eight hours to fill a modern Android. A 10,000mAh bank with a 30W USB Power Delivery (PD) port does it in about 90 minutes.

What to look for:

18W minimum for phones — the floor for anything resembling fast charging
30W USB-C PD for iPhones, recent Android flagships, and iPad
60W or 65W if you want to top up a lightweight laptop on the go

USB PD isn't just about speed — it negotiates the right wattage for each device automatically. Your earbuds charge gently; your phone charges as fast as it can accept. One port with PD does more useful work than three ports without it.

Ports: One Is Rarely Enough

Once you're travelling with a phone, earbuds, and a smart watch, a single port becomes a juggling act. Look for a combination:

USB-C (PD) — your primary fast-charge port and how you recharge the bank itself
USB-A — for older accessories and cables you already own
Two ports — essential if you want to charge two devices simultaneously

Note that total output drops when multiple ports are in use — a bank rated at 30W on USB-C might split to 18W + 12W when the USB-A port is also active. That's fine; just know it happens.

Weight vs Capacity: The Trade-Off Nobody Mentions

A 20,000mAh power bank typically weighs 350–450g. If you're already carrying a laptop, that's nearly another half-kilogram on your shoulder. Most commuters find that a 10,000mAh bank — around 170–220g — disappears into their bag and they actually carry it every day. The heavy one stays home.

Don't Forget the Cable

A power bank is only as useful as the cable you pair with it. The most common travel frustration is finding that the cable you packed doesn't fit the device that needs charging most urgently.

For mixed-device trips — your phone, a partner's different phone, earbuds — a 3-in-1 charging cable with USB-C, Lightning and Micro-USB tips means one cord covers the whole bag. For a dedicated USB-C setup — newer Androids, iPad, lightweight laptop — a nylon-braided USB-C cable survives the daily bag-bottom abuse that flimsy cables don't.