Power banks are sold by a single big number — mAh — and it's the main thing shoppers get wrong. Buy too small and it's flat before you are; too big and you're carrying a brick you never fully use. Here's how to pick the right size in plain English.
What mAh actually means for your phone
mAh (milliamp-hours) is the size of the power bank's tank. Most modern phones hold roughly 3,000–5,000mAh. But you never get the full number in real life — energy is lost as heat and conversion, so a good rule is that you'll get about 65–70% of the labelled capacity into your phone. A 10,000mAh bank therefore gives most phones roughly two full charges, not three.
10,000mAh — the everyday pocket backup
This is the sweet spot for most people. It's slim, light, fits in a pocket or small bag, and gives you about two full phone charges — enough to get through a long day, a commute, or a night out without hunting for a plug. If you just want peace of mind that your phone won't die, this is your size.
20,000mAh — the travel and multi-device choice
Double the capacity means about four phone charges, or enough to top up a phone, tablet and earbuds across a couple of days. It's the right pick for travel, long flights, camping, or anyone who charges more than one device. The trade-off is size and weight — it's noticeably bulkier.
Don't ignore output (watts) and ports
Capacity is only half the story. Output decides how fast it charges. Look for USB-C Power Delivery (PD) if you want fast charging — an 18W or higher output will refill a phone far quicker than a basic 5W bank. Also check the number of ports if you charge more than one thing at once, and make sure it has the cable type your devices use.
Quick pick by situation
Daily backup for one phone → 10,000mAh. Frequent traveller or multiple devices → 20,000mAh. Want the fastest charge → prioritise USB-C PD and 18W+ output over raw capacity. Barely leave the house → a smaller 5,000mAh bank is enough.
Frequently asked questions
Why doesn't a 10,000mAh bank fully charge my phone three times?
Because of energy lost to heat and voltage conversion, you get about 65–70% of the rated capacity in practice — so roughly two full charges for most phones.
Can I take a power bank on a plane?
Yes. Power banks must go in your carry-on, not checked luggage. Most airlines allow up to 100Wh, which covers virtually all 10,000 and 20,000mAh banks — but always check your airline's rules.
Does a bigger power bank charge my phone faster?
No — speed comes from output (watts), not capacity (mAh). A high-capacity bank with low output will still charge slowly.
What output should I look for?
For fast phone charging, look for USB-C Power Delivery with at least 18W. Each product page lists the output so you can compare.
Find the right size for how you actually live. Every Mobcos power bank is genuine, ships free across the UAE, and you can pay by card, Cash on Delivery, or split it with Tamara and Tabby. Shop power banks now.
