What size power bank do I need?
For most people, a 10,000 mAh power bank is enough for about one and a half to two full phone charges, which covers a long day out. Choose 20,000 mAh for travel, several devices, or two to four phone charges, and 5,000 mAh if you only need a single top-up in a pocket. For a laptop, look for at least 20,000 mAh plus USB-C Power Delivery output that matches your laptop's wattage.
How many charges will a power bank give?
A power bank never delivers its full rated capacity. Its cells are rated at about 3.7 volts, but USB charging runs at 5 volts or more, and some energy is lost as heat during conversion. In practice, expect roughly 60 to 70 percent of the rated mAh to reach your device.
Quick formula: charges ≈ (power bank mAh × 0.65) ÷ your device's battery mAh.
| Power bank capacity | Approx. usable capacity | Approx. phone charges (4,000 mAh phone) | Best for |
|---|---|---|---|
| 5,000 mAh | ~3,000-3,500 mAh | ~0.75-1 | Pocket emergency top-up |
| 10,000 mAh | ~6,000-7,000 mAh | ~1.5-2 | Daily carry, commuting |
| 20,000 mAh | ~12,000-14,000 mAh | ~3-3.5 | Travel, festivals, multiple devices |
| 26,800 mAh | ~16,000-18,500 mAh | ~4-4.5 | Long trips, tablets, some laptops |
Actual results depend on your phone's battery size, cable, charging speed, temperature, and the age of the power bank.
How to choose a portable charger in 6 steps
- List your devices and battery sizes. Phones are typically around 3,000 to 5,000 mAh; tablets and laptops are much larger.
- Pick a capacity using the table above and how many charges you need between outlets.
- Check output power (watts). Fast phone charging generally needs 18 to 30 W via USB-C PD; laptops often need 45 to 65 W or more. Match the power bank to your device's supported standard.
- Count the ports. Make sure there are enough outputs, and the right types (USB-C, USB-A), for everything you charge at once.
- Decide on extras. Wireless or magnetic charging, a digital battery display, built-in cables, or solar panels for outdoor use.
- Balance size and weight. Higher capacity means a heavier, bulkier bank. Slim 5,000 to 10,000 mAh models fit pockets; 20,000 mAh models usually belong in a bag.
Which type of power bank fits you?
- Magnetic wireless (MagSafe-style), about 5,000 mAh: snaps to compatible phones for a cable-free top-up. Example: MagSafe-Style 5000mAh Magnetic Wireless Power Bank.
- Wireless Qi, around 10,000 mAh: lay a Qi-compatible phone on top. Example: Wireless Power Bank Qi Fast Charger.
- High-capacity 20,000 mAh: for trips and multiple devices. Examples: 20000mAh Power Bank with LED Display and USB-C Fast Charging and the 20000mAh Slim Power Bank.
- Solar power banks: useful as a backup outdoors, but solar panels on a power bank recharge slowly, so plan to charge it from an outlet before you leave. Example: Solar Power Bank, Waterproof, Dual USB.
Can you bring a power bank on a plane?
Yes, but under U.S. FAA and TSA rules, power banks must go in your carry-on bag, not checked luggage. Batteries up to 100 watt-hours (Wh) are generally allowed; 100 to 160 Wh typically needs airline approval; above 160 Wh is not allowed. Airlines can set stricter rules, so check with your carrier before flying.
To convert: Wh = mAh × 3.7 ÷ 1,000. A 20,000 mAh bank is about 74 Wh and a 26,800 mAh bank is about 99 Wh, both under 100 Wh.
What is the difference between mAh and Wh?
mAh (milliamp-hours) describes charge at the battery's own voltage. Wh (watt-hours) describes total energy and lets you compare batteries at different voltages, which is why airlines use it. For shopping between power banks, mAh is fine; for flying or comparing with a laptop battery, use Wh.
Power bank mistakes to avoid
- Buying by mAh alone without checking whether the output wattage can actually fast-charge your device.
- Expecting a 10,000 mAh bank to charge a 5,000 mAh phone twice.
- Packing a power bank in checked luggage.
- Leaving it in a hot car or direct sun, which shortens battery life.
- Using damaged or swollen power banks. Stop using any battery that is puffy, hot, or cracked.
Shop power banks at Arbasa
Browse every capacity in our power banks collection, or see the wider range of chargers and power. Planning a trip? Read our power banks for travel guide.
Frequently asked questions
Is 10,000 mAh enough for a day?
For most phone users, yes. A 10,000 mAh power bank typically delivers around one and a half to two full charges of a typical smartphone.
Is 20,000 mAh too big?
Not if you travel, share it with others, or charge a tablet. It is heavier than a 10,000 mAh bank, so it is less convenient for daily pocket carry.
How many times can a 20,000 mAh power bank charge a phone?
Usually about three to four times for a phone with a 3,000 to 4,000 mAh battery, depending on efficiency and charging conditions.
Can a power bank charge a laptop?
Only if it has USB-C Power Delivery output with enough wattage for your laptop, often 45 W or more. Check both the power bank's output rating and your laptop's charging requirements.
How long does a power bank last?
Most lithium power banks are designed for several hundred charge cycles before capacity noticeably declines. Store them partly charged in a cool place to extend their life.
