Best Portable Power Banks Under $40
Stay charged anywhere with these reliable and affordable portable chargers
Affiliate Disclosure: This post contains affiliate links. If you make a purchase through these links, we may earn a commission at no additional cost to you. We only recommend products we believe will add value to our readers. Learn more
Written by Maria Dillon
•8 min readGrandmother, maker, and practical tech reviewer. I help families (and their pets!) find budget-friendly gadgets that solve real problems. Every product is tested with decades of hands-on experience and a maker's eye for quality.
Running out of battery at the worst possible moment is frustrating. Whether you're traveling, commuting, or just having a long day away from outlets, a reliable portable power bank is essential. The good news? You don't need to spend a fortune to stay charged. We've tested dozens of power banks to find the best options under $40 that deliver reliable performance, fast charging, and great value.
What to Look for in a Power Bank
Capacity (mAh)
10,000mAh charges most phones 2-3 times
Fast Charging
Look for 18W+ output for quick charging
Multiple Ports
Charge multiple devices simultaneously
Safety Features
Overcharge and short-circuit protection
1. Anker PowerCore 10000
The Anker PowerCore 10000 is our top pick for good reason. It's incredibly compact (about the size of a credit card), yet packs enough power to charge an iPhone 13 about 2.5 times or a Galaxy S21 twice. Anker's reputation for reliability shines through with excellent build quality and safety features.
Key Specs
- • Capacity: 10,000mAh
- • Output: 12W (2.4A)
- • Weight: 6.35 oz
- • Ports: 1 USB-A
Best For
- • Daily commuting
- • Travel (TSA-friendly)
- • Emergency backup
- • Pocket-friendly portability
2. INIU 10000mAh Slim Power Bank
The INIU power bank offers exceptional value with its slim design and USB-C input/output capability. It's slightly thinner than the Anker, making it even more pocket-friendly. The built-in flashlight is a nice bonus for emergencies or finding items in your bag at night.
Key Specs
- • Capacity: 10,000mAh
- • Output: 22.5W (USB-C)
- • Weight: 6.7 oz
- • Ports: USB-C + USB-A
Best For
- • USB-C device owners
- • Budget-conscious buyers
- • Outdoor activities
- • Multi-device charging
3. Miady 2-Pack 10000mAh Power Banks
Get two power banks for less than the price of one premium option! This Miady 2-pack is perfect for families or if you want one for home and one for travel. Each unit provides dual USB outputs so you can charge two devices at once. The LCD display shows exact battery percentage, eliminating guesswork.
Key Specs
- • Capacity: 10,000mAh each
- • Output: 12W total (2x USB-A)
- • Weight: 8 oz per unit
- • Display: LCD battery indicator
Best For
- • Families with multiple devices
- • Having backup options
- • Sharing with travel companions
- • Maximum value per dollar
4. Charmast 10400mAh with Built-in Cables
Forget carrying extra cables! The Charmast features built-in Lightning, USB-C, and Micro-USB cables, making it incredibly convenient for on-the-go charging. The slightly higher capacity (10,400mAh) gives you a bit more juice per charge, and the integrated cables mean you'll never forget your charging cable again.
Key Specs
- • Capacity: 10,400mAh
- • Output: 15W (3 cables + 1 USB-A port)
- • Weight: 8.5 oz
- • Built-in cables: Lightning, USB-C, Micro-USB
Best For
- • People who forget cables
- • Mixed device households
- • Minimal packing
- • Charging up to 4 devices at once
5. Baseus 20000mAh Power Bank
If you need maximum capacity at this price point, the Baseus 20000mAh is your answer. This power bank can charge most phones 4-5 times, making it ideal for long trips, camping, or anyone who goes days without access to outlets. The 20W USB-C output supports fast charging for compatible devices.
Key Specs
- • Capacity: 20,000mAh
- • Output: 20W (USB-C PD)
- • Weight: 13.4 oz
- • Ports: 2x USB-A + 1x USB-C
Best For
- • Extended travel
- • Camping and outdoor adventures
- • Heavy device users
- • Charging tablets and laptops
Quick Comparison
| Power Bank | Price | Capacity | Best Feature |
|---|---|---|---|
| Anker PowerCore | $25.99 | 10,000mAh | Ultra-compact size |
| INIU Slim | $19.99 | 10,000mAh | Best value |
| Miady 2-Pack | $29.99 | 20,000mAh total | Two units included |
| Charmast | $24.99 | 10,400mAh | Built-in cables |
| Baseus | $39.99 | 20,000mAh | Highest capacity |
Common Questions
How many times can a 10,000mAh power bank charge my phone?
A 10,000mAh power bank can typically charge an iPhone 13 about 2-3 times or a Samsung Galaxy S21 about 2 times. The exact number depends on your phone's battery capacity and charging efficiency (usually around 70-80%).
Can I bring a power bank on an airplane?
Yes! All the power banks in this guide are under the TSA's 100Wh limit (27,000mAh) and can be carried in your carry-on luggage. They cannot be checked in your luggage. Always keep them in your carry-on bag.
How long does it take to recharge a power bank?
A 10,000mAh power bank typically takes 4-6 hours to fully recharge using a standard 5W charger, or 2-3 hours with a fast charger (18W+). The 20,000mAh Baseus takes about 6-8 hours with a standard charger.
Do power banks lose charge when not in use?
Yes, but slowly. Quality power banks like these lose about 5-10% of their charge per month when not in use. It's a good idea to top them up every few months if you're keeping them as emergency backup.
Our Top Pick
For most people, the Anker PowerCore 10000 offers the best balance of size, capacity, reliability, and price. If you need built-in cables for convenience, go with the Charmast. For maximum capacity, the Baseus 20000mAh can't be beaten. And if you want the best deal, the INIU or Miady 2-Pack deliver excellent value.
Whichever you choose, you'll never have to worry about running out of battery at the worst possible moment again!
Related Articles
Best Solar Chargers for Camping
Harness the power of the sun for unlimited charging on your outdoor adventures
Best Wireless Earbuds Under $50
Amazing audio quality without the premium price tag
Budget Phone Accessories Under $30
Essential phone accessories that don't break the bank
Smart Home Energy-Saving Gadgets
Cut your energy bills with these smart home devices