How Many Times Can a 20000mAh Power Bank Charge a Phone?
A 20000mAh power bank charges a typical 5000mAh phone about 2.5–3 times. See why, a quick table by phone battery size, and genuine picks in Bangladesh.
By Lagbe Editorial TeamProduct & buying advice
Published Prices checked November 2026
- 2 picks
- 2 products compared
- ৳2,250 – ৳3,990
- 100% genuine
Quick answer
A 20000mAh power bank charges a typical 5000mAh phone about 2.5–3 times. Real-world output is roughly 60–70% of the rated capacity (about 12,000–14,000mAh) because of voltage conversion and heat.
Power banks are rated at their internal battery voltage (3.7V), but phones charge at 5V or more. Converting between them, plus heat and cable losses, means you never get the full 20000mAh into your phone.
At a glance
How we pick products
- Only genuine products from the brand or its authorised distributor in Bangladesh.
- Prices are checked against the Bangladeshi market every month and shown in BDT.
- We look at what buyers in Bangladesh actually choose on Lagbe, and add buyer ratings as reviews come in.
- Specs come from the brand's official information; we don't accept payment for placement.
Our picks
- 1Best value 20000mAh
Baseus Bipow 20000mAh 20W Power Bank
High capacity with 20W output at a budget price — ideal for load-shedding backup.
৳2,250Regular price ৳2,495 - 2Faster 22.5W option
Anker PowerCore 22.5W Power Bank
Available in 10000mAh and 20000mAh, so you can choose pocket-size or full-day capacity.
from৳2,990
Approximate full charges from a 20000mAh power bank
| Phone battery | Typical phones | Approx. full charges |
|---|---|---|
| 3,500mAh | Older or compact phones | 3.5–4 |
| 4,500mAh | Many mid-range phones | 2.8–3 |
| 5,000mAh | Most new Android phones | 2.5–2.8 |
| 6,000mAh | Big-battery phones | 2–2.3 |
The quick math
Usable capacity ≈ rated capacity × 0.65. For 20000mAh that's about 13,000mAh. Divide by your phone's battery size: 13,000 ÷ 5,000 ≈ 2.6 full charges.
Can I take a 20000mAh power bank on a plane?
Usually yes, in your cabin bag only. 20000mAh at 3.7V is about 74Wh, under the common 100Wh airline limit. Power banks are not allowed in checked luggage — check your airline's rules before flying.
Frequently asked questions
How many times can a 20000mAh power bank charge a phone?
About 2.5–3 times for a typical 5000mAh phone, because only around 60–70% of the rated capacity reaches the phone.
Why doesn't 20000mAh give four full charges?
Energy is lost converting the battery's 3.7V to your phone's charging voltage, and as heat. Expect about 13,000mAh of usable capacity.
Is a 20000mAh power bank allowed on flights?
Generally yes in cabin baggage, since it's about 74Wh — below the usual 100Wh limit. It's not allowed in checked baggage.
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