Lauren HollandBy Lauren Holland

Updated November 2026

The anker power bank 20k 87w is a high-capacity portable charger built to power laptops as well as phones and tablets. This guide explains what the 20,000mAh capacity and 87W output mean in practice, how to match the bank to your devices, and how to get the most out of it. Most of the confusion comes from mixing up battery capacity with actual charging output, so we will untangle that first.

What the 20K and 87W Numbers Actually Mean

The “20K” figure is the rated capacity in milliamp-hours, which is the total charge stored in the cells. Because of conversion losses between the internal battery and the USB output, you will get noticeably less than 20,000mAh into a device. A rough planning figure is around 60 to 70 percent of the rated capacity for real-world use.

Shopping for one? See our guide: 6 Best Anker Zolo Power Banks for Travel and Everyday Use (2026).

The “87W” figure is the maximum power the USB-C port can deliver to a compatible device. That is enough for many laptops, but only when the laptop itself accepts that wattage. The bank supplies what the device requests, so a phone will draw far less than 87W even when plugged into the same port.

Step 1: Check Your Device’s Charging Requirements

Before relying on the bank for a laptop, confirm the wattage your laptop charger is rated for. Most ultrabooks use 45W to 65W, while larger gaming or workstation laptops may request 100W or more. A laptop that needs more than the bank can supply will charge slowly or not at all.

  1. Read the output rating printed on your laptop’s original charger.
  2. Confirm the laptop supports USB-C Power Delivery charging, not just a proprietary plug.
  3. Use a USB-C cable rated for the power level you need. Cables labeled for 100W or 240W are the safest choice.

Step 2: Choose the Right Port and Cable

The 87W output is available on the USB-C Power Delivery port only. Connect your laptop there, and use the USB-A port for accessories such as earbuds or a mouse receiver, which draw very little power. Running two high-draw devices at once will split the available output.

Device Typical Power Need Port to Use
Smartphone 18W to 30W USB-C
Ultrabook laptop 45W to 65W USB-C (PD)
Tablet 20W to 30W USB-C
Wireless earbuds Under 5W USB-A

Step 3: Estimate Runtime Before You Travel

To estimate how many charges you can expect, divide the usable capacity by your device’s battery size. A phone with a 5,000mAh battery, for example, will take roughly three full charges from a 20,000mAh bank after conversion losses. For laptops, check the battery’s watt-hour rating instead, since that figure is the accurate measure. If you are unsure how capacity translates to real use, our guide How to Choose a Power Bank: Capacity and Key Features explains the math in more detail.

Common Mistakes to Avoid

  • Assuming 87W means every device will charge at that speed. The device sets the draw.
  • Using a cheap or damaged cable, which can limit output well below the rated figure.
  • Charging the bank and a laptop at the same time in a hot car or direct sunlight.
  • Ignoring airline rules. Lithium power banks are generally allowed in carry-on luggage but not in checked bags.
  • Forgetting to recharge the bank before a trip, since a 20,000mAh pack takes a good while to refill.

A certified USB-C to USB-C cable rated for high wattage is the most useful accessory, because it ensures the 87W port can actually deliver its output. A compact travel pouch helps protect the bank from pressure and keeps the cable with it. For comparisons with other Anker models, see Anker Zolo Power Bank 20 000mah: 6 Best Picks for Travel and Everyday Use (2026).

  • USB-C 100W cable: Supports full Power Delivery for laptops and avoids the bottleneck of thin cables. View on Amazon
  • Anker PowerCore 20K 87W: Designed for the same class of high-output laptop charging. View on Amazon

FAQ

Can the anker power bank 20k 87w charge a laptop?

Yes, if your laptop supports USB-C Power Delivery and needs 87W or less. Check the wattage on your original charger first.

Will it fully charge a phone several times?

Usually two to four full charges for a typical smartphone, depending on the battery size and conversion losses.

Is it allowed on airplanes?

Power banks of this size are generally permitted in carry-on bags, but airline and regional rules vary, so check before you fly.

Conclusion

The anker power bank 20k 87w is best understood as a high-output charger with usable capacity closer to 60 to 70 percent of its rating. Match the 87W port to devices that request that wattage, use a quality cable, and plan runtime around your device’s real battery size. Following these steps will keep charging fast and predictable on the road.

Ready to choose one?

Lauren Holland

About Lauren Holland

Lauren Holland is part of our editorial team and reviews and edits our consumer tech how-to & troubleshooting guides, checking product details against manufacturer specifications and owner feedback.