Choosing a power bank
How to choose a power bank — 3 things to check before mAh
Check three things first: (1) the energy that actually reaches your phone is less than the rated mAh, (2) output watts and USB-C Power Delivery support, and (3) airline rules (from April 20, 2026: two per person, 160Wh max). For phones only, 10,000mAh at around 20W is plenty; to top up a tablet or laptop, look for USB-C PD at 45W or more.
Product pages lead with mAh, but output and port layout decide how happy you'll be.
1. mAh is a cell-level number
Rated mAh is measured at the internal cell voltage (usually 3.6–3.85V). Charging a phone means converting up to 5V or 9V, and conversion losses mean less energy reaches the phone than the label suggests.
Compare in Wh instead: Wh = mAh × rated voltage ÷ 1000
Two 10,000mAh units can deliver different real amounts depending on efficiency.
2. Output watts and USB-C PD
Phone only → around 20W covers most phones' fast charging.
Tablet or laptop → check USB-C PD output of 45W or more. Far below your laptop charger's wattage means slow charging, or just slowing the drain while in use.
With several ports in use, output is shared. "Up to 45W" usually means a single port.
3. Can you fly with it?
From April 20, 2026: two per person, 160Wh max each, no in-flight use. 10,000mAh (≈37Wh) and 20,000mAh (≈74Wh) are comfortably within the limit. Details: Power banks on flights
Grouped by output
Checked on this site; prices and stock as of each card's date.
[10,000mAh · 22.5W] — light, phone-focused
AliExpress테크/가전AEO 99베이스어스 10000mAh 22.5W 파워뱅크 USB-C 내장형
- ✓브랜드: Baseus
- ✓판매처 판매가: $27.13 (확인 시각 기준)
- ✓브랜드 표기: Baseus
US$29
확인 2026. 10. 01.
[10,000mAh · 45W] — small, can top up tablets and laptops
AliExpress테크/가전AEO 98베이스어스 45W 미니 파워뱅크 10000mAh
- ✓브랜드: Baseus
- ✓판매처 판매가: $43.73 (확인 시각 기준)
- ✓브랜드 표기: Baseus
US$44
확인 2026. 10. 01.
amazon생활용품AEO 87INIU 10000mAh 45W 고속 충전 휴대용 충전기, 소형 여행용 파워뱅크
- ✓45W 고속 충전 지원
- ✓10000mAh 용량
- ✓부착된 USB-C 케이블
US$22
확인 2026. 09. 15. · 확인 후 30일 경과
[20,000mAh · 22.5W / 45W] — travel, multiple charges
AliExpress테크/가전AEO 98Baseus Power Bank 20000mAh PD 22.5W Fast Charging
- ✓브랜드: Baseus
- ✓판매처 판매가: $27.89 (확인 시각 기준)
- ✓브랜드 표기: Baseus
US$31
확인 2026. 10. 01.
AliExpress테크/가전AEO 98Vention CCC 45W 20000mAh 보조배터리
- ✓브랜드: Vention
- ✓판매처 판매가: $43.73 (확인 시각 기준)
- ✓브랜드 표기: Vention
US$40
확인 2026. 10. 01.
FAQ
Q. How many phone charges do I get from 10,000mAh?
It depends on your phone's battery and the unit's efficiency; rated mAh overstates delivered energy. Compare Wh and output rather than a "number of charges".
Q. How many watts do I need for a laptop?
Start from your laptop charger's wattage. A power bank with much lower USB-C PD output charges slowly or only slows the drain. 45W and up is the usual starting point.
Sources
Airline rule: Korea.kr https://www.korea.kr/news/policyNewsView.do?newsId=148962298
Capacity and output figures are the seller's listed specs on each product page. Compiled 2026-10-01. Some links are affiliate links (no effect on your price).
한국어: How to choose a power bank — 3 things to check before mAh