A phone power bank won’t keep a laptop alive. To charge a laptop, you need enough power output (watts), enough capacity (watt-hours) and the right USB-C standard. This guide explains those numbers, the airline rules to know, and the types of laptop power banks worth considering.
Quick answer
- Thin laptops (MacBook Air, ultrabooks): 20,000mAh with 45–65W USB-C output.
- Larger laptops (MacBook Pro, 16″ Windows): 24,000–27,000mAh with 100–140W output.
- Air travel: stay under 100 Wh (roughly 27,000mAh) for carry-on without airline approval.
- Gaming laptops with barrel chargers: most won’t charge meaningfully from a power bank.
The numbers that matter
Output (watts)
Check your laptop’s charger wattage. A power bank with lower output may still charge slowly, or only slow the battery drain while you work. Match the charger, or at least get close.
Capacity (mAh vs. Wh)
mAh ratings are measured at the internal battery voltage (about 3.6–3.85V). Watt-hours are more useful: Wh = mAh × V ÷ 1000. A 20,000mAh bank is about 72–77 Wh. Because of conversion losses, expect roughly 60–70% of that to reach your laptop. Compare with your laptop’s battery capacity (for example, many 13-inch ultrabooks have 50–60 Wh batteries).
USB Power Delivery
Laptops charge over USB-C using the USB Power Delivery (PD) standard. Outputs above 100W require PD 3.1 and a 240W-rated (EPR) cable. Your laptop must support USB-C charging — look for a charging icon near the port or check the manual.
Types to consider
High-power (100–140W+): Anker 737 and similar
Large-capacity banks with a display and very high output for power-hungry laptops and fast recharging. Heavy, but the most capable. See our Anker 737 review. Brands like UGREEN (Nexode) and CUKTECH also offer high-output models.
Thin laptop banks (65–100W): Baseus Blade and similar
Flat designs slide into a laptop sleeve next to your computer. Enough for ultrabooks and MacBook Air models, with less bulk than cylinder or brick designs.
Everyday 20,000mAh with 45–65W
The value category: good for topping up a thin laptop and charging phones for days. Check the USB-C port’s wattage — many list a high total that’s split across ports.
Flying with power banks
- Power banks must go in carry-on, never checked luggage.
- Under 100 Wh is generally allowed; 100–160 Wh usually needs airline approval; above 160 Wh is generally prohibited.
- Some airlines now restrict using or charging power banks in flight — check your airline’s current policy.
- Choose banks with the Wh rating printed clearly on the case.
Need a wall charger too? See our USB-C laptop charger guide. Battery wearing out? Read our laptop battery replacement guide.