In this guide
You need a power bank with at least 45–65W USB-C Power Delivery output to charge most laptops — match or exceed the wattage printed on your laptop’s original charger.
- Power bank outputs ≥45W via USB-C PD (65–100W for pro or gaming laptops)
- Capacity is 20,000mAh or higher (ideally 100Wh equivalent)
- You use a high-quality USB-C cable rated for the required wattage
- Output is under 45W — phone-style banks (10–22.5W) won’t charge a laptop under load
- The power bank lacks USB-C PD voltage negotiation (laptops need 15–20V)
- Capacity is under 20,000mAh — you’ll get only a partial top-up
How to Find the Right Wattage
Check the label on your laptop’s original charger. Multiply volts × amps to get watts (e.g., 20V × 3.25A = 65W). Your power bank must meet or beat that number. A bank that falls short will either fail to charge at all or slowly drain while you’re using the laptop.
Wattage by Laptop Type
| Setup | Works? | Need | Note |
|---|---|---|---|
| Ultrabook (MacBook Air, thin Windows) | Yes | 45W USB-C PD | 30–45W chargers standard |
| Mid-range laptop (MacBook Pro 14, Dell XPS) | Yes | 65W USB-C PD | Match charger wattage exactly |
| Pro / creative laptop | Yes | 90–100W USB-C PD | Most banks cap at 100W |
| Gaming laptop | Rarely | 100W+ | Many exceed portable bank limits |
| Phone power bank (USB-A or low-W) | No | — | 10–22.5W too low for laptops |
Capacity: How Long Will It Last?
Wattage tells you whether the bank can charge your laptop. Capacity (mAh or Wh) tells you for how long. Aim for at least 20,000mAh. To estimate runtime, use this formula: Runtime ≈ Wh × 0.85 ÷ laptop wattage draw. A 96Wh bank powering a 45W laptop gives roughly 1.8 hours of charging.
Note: Airlines allow a maximum of 100Wh per power bank in carry-on luggage — most 26,800mAh banks sit just above this, so check the Wh rating before you fly.
USB-C PD Is Non-Negotiable
Laptops require USB Power Delivery (USB-C PD) to negotiate the 15–20V they need. A standard USB-A port or a USB-C port without PD will not work. Always confirm the spec sheet lists “USB-C PD” — not just “USB-C.” If you’re unsure whether your laptop’s USB-C port handles power, check out what USB-C ports actually support before buying.
Cable Matters Too
Even the right power bank will underperform with a low-rated cable. Use a USB-C cable rated for at least the wattage you’re delivering — preferably a 100W or 5A cable for anything above 60W. If you run into charging issues, the same principles that cause USB-C signal problems often apply to power delivery failures: cable quality and port compatibility are the usual culprits.
Bottom line: For most laptops, a 65W USB-C PD power bank with 20,000mAh or more is the safe, reliable choice. Ultrabook users can get away with 45W; pro and creative laptop users should go to 100W. Skip any bank that doesn’t explicitly list USB-C PD output — wattage alone on a USB-A port will not charge your laptop.