Quick Answer

Before buying a power bank, check three numbers: capacity in mAh, output wattage (W), and the port type your devices need. For a phone, a 10,000–20,000 mAh bank with 20W+ USB-C PD (around R350–R800 at Evetech) covers two to four full charges. For a laptop, you need 65W–100W USB-C PD output and 20,000 mAh+. Match the bank's wattage to the device, not just its capacity.

Checklist 1: Capacity For The Device

Capacity (mAh) sets how many charges you get. A 10,000 mAh bank gives a typical phone roughly two full charges; 20,000 mAh gives three to four and can top up a tablet. For a laptop, you want 20,000 mAh or more, since laptops draw far more energy. Note that usable capacity is around 60–70% of the rated figure after conversion losses.

Checklist 2: Output Wattage And PD

Wattage decides whether the bank can charge a device at all, and how fast. Phones fast-charge at 18–30W USB-C Power Delivery (PD). Laptops need 65W (ultrabooks) to 100W (larger laptops) USB-C PD — a 20W phone bank will not charge most laptops. Check the bank lists the exact PD wattage your device requires, not just "fast charge."

Checklist 3: Ports And Pass-Through

Confirm the port type: modern devices use USB-C, older ones USB-A. A bank with USB-C PD in and out is the most flexible. If you want to charge the bank and a device at once, look for pass-through charging. For air travel, ensure capacity is under the 100Wh airline limit (most 20,000 mAh banks qualify at around 74Wh).

FAQ

What capacity power bank do I need?

For a phone, 10,000–20,000 mAh gives two to four charges. For a laptop, choose 20,000 mAh or more. Remember usable capacity is about 60–70% of the rated mAh after conversion losses.

Can any power bank charge a laptop?

No — laptops need 65W–100W USB-C Power Delivery output. A 20W phone bank will not charge most laptops. Check the bank's exact PD wattage matches your laptop's charger requirement before buying.

Are power banks allowed on flights?

Most are, if under 100Wh — a typical 20,000 mAh bank is around 74Wh and qualifies for carry-on. Always carry power banks in hand luggage, never checked, and check your airline's specific limit.

TIP

to the device, not just mAh — a phone needs 20W+ USB-C PD, a laptop needs 65–100W; a high-capacity bank with low wattage will not charge a laptop at all.