Rated vs cell capacity
Usable output vs the printed cell rating.
Why it matters
Real output ≈ 60–70% of the label. A 10,000 mAh bank gives roughly 6,500 mAh.
What to check
Good brands print 'rated capacity' on the back — compare that.
Electronics
Power Bank
A 20,000 mAh power bank does not give 20,000 mAh to your phone. Voltage conversion eats a third of it, and the output wattage decides whether it charges your laptop at all.
Find your fit
A few questions about your situation, not about the product.
Answer all 2 questions to see the spec sheet to shop with.
The spec sheet, decoded
Output wattage & protocol
PD (Power Delivery), QC (Quick Charge) and watts.
Why it matters
Phones want 18–30W PD; laptops need 45–65W PD. Mismatched protocol means slow charging.
What to check
'22.5W max' is often shared across ports, not per port.
Input charging speed
How fast the bank itself refills.
Why it matters
A 20,000 mAh bank with 10W input takes 8+ hours to recharge.
What to check
Look for 30W+ input on large banks.
Ports & pass-through
USB-C, USB-A count, and charging while being charged.
Why it matters
USB-C in/out is essential now; pass-through is handy overnight.
What to check
Some banks only charge via micro-USB — outdated.
Cell type & safety
Li-ion vs Li-polymer, plus protection circuitry.
Why it matters
Li-polymer is safer and slimmer; BIS certification matters for flights and safety.
What to check
Airlines restrict banks above 100 Wh (~27,000 mAh).
Weight
Grams you'll actually carry.
Why it matters
20,000 mAh banks weigh ~400 g — heavy for daily pocket carry.
What to check
Match size to whether it's for travel or daily bag.
Before you pay
- ✓Decide daily carry (10,000 mAh) vs travel (20,000 mAh).
- ✓Check output watts per port and PD support for your device.
- ✓Confirm USB-C input at 30W+ on big banks.
- ✓Look for BIS certification and printed rated capacity.
Common traps
- !Ultra-cheap 20,000 mAh banks with fake capacity and no protection.
- !Buying a 65W bank for a phone that only takes 18W.
- !Banks too large to carry on flights.
10,000 mAh pocket banks to 20,000 mAh 65W laptop-capable units.