Not all power banks can charge laptops. While any power bank can top up your smartphone, laptops require specific features that many portable chargers lack. If you've ever tried charging your laptop from a phone-sized power bank only to find it doesn't work, or works frustratingly slowly, you've encountered this limitation first-hand.
This guide explains what laptops need from a power bank, how to match power bank specifications to your laptop's requirements, and what to consider when purchasing a laptop-capable portable charger.
Why Regular Power Banks Won't Work
Standard power banks designed for phones typically output 5-12 watts of power. This is sufficient for smartphones, which have small batteries and efficient charging circuits. Laptops, however, are a different beast entirely.
Even ultralight laptops require 30-45 watts for meaningful charging, while larger laptops need 60-100 watts or more. A standard power bank simply cannot provide this power level. Connecting your laptop to an underpowered source typically results in one of three outcomes:
- No charging at all; the laptop doesn't recognise the power source
- Extremely slow charging that barely keeps up with idle power draw
- The laptop drains slower but still loses charge overall
To charge a laptop effectively, you need a power bank with USB-C Power Delivery (PD) at appropriate wattage levels.
Understanding Power Requirements
Check Your Laptop's Charger
The first step is determining how much power your laptop actually needs. Look at your laptop's original charger; it will list output specifications in watts (W) or as voltage (V) and current (A).
Common laptop power requirements:
- MacBook Air: 30-35W
- MacBook Pro 14": 67W
- MacBook Pro 16": 96-140W
- Dell XPS 13: 45-65W
- Surface Pro: 65W
- ThinkPad X1 Carbon: 65W
- Gaming laptops: Often 100W+ (many not USB-C chargeable)
If your charger shows voltage and amps instead of watts, multiply them: Watts = Volts × Amps. For example, 20V × 3A = 60W.
Can You Charge with Less Power?
Many laptops can charge from lower wattage than their original charger, just slower. A laptop that comes with a 65W charger might charge acceptably from a 45W source when idle or doing light work.
However, if you're running demanding applications while connected to an underpowered source, the laptop may consume power faster than it receives. You'll see the battery slowly drain even while "charging."
As a rule of thumb, aim for a power bank that provides at least 75% of your laptop's original charger wattage for usable charging during light work. For charging while the laptop is off or sleeping, lower wattage works fine but takes longer.
USB-C Power Delivery Requirements
Laptop charging requires USB-C ports with Power Delivery (PD) protocol at appropriate wattage. Not all USB-C ports are equal; many provide only standard 5V/3A (15W) output. For laptops, you need:
Wattage Tiers
- 45W USB-C PD: Entry level for laptop charging. Works for ultrabooks and charging larger laptops slowly when idle.
- 60-65W USB-C PD: The sweet spot for most ultrabooks and thin laptops. Matches or nearly matches typical chargers.
- 87-100W USB-C PD: Required for larger laptops like MacBook Pro 16". Fewer power banks offer this level.
Check power bank specifications carefully. A power bank might advertise "100W output" but deliver that only from USB-A ports combined, not from USB-C PD. The USB-C PD specification is what matters for laptop charging.
- USB-C port with Power Delivery (PD) protocol
- Output wattage matching your laptop (45-100W typically)
- High capacity (20,000mAh+) for meaningful runtime
- Airline-compliant capacity if you fly (under 100Wh/27,000mAh)
Capacity Considerations
Laptop batteries are much larger than phone batteries, so you need more power bank capacity for useful laptop charging. However, there's an upper limit imposed by airline regulations.
Calculating Runtime
A rough estimate: divide the power bank's capacity in watt-hours (Wh) by your laptop's power consumption to get runtime hours. Account for about 15% efficiency loss.
Example: A 100Wh power bank with a laptop consuming 30W (light work on an ultrabook): 100Wh × 0.85 efficiency ÷ 30W = approximately 2.8 hours of additional runtime
For most laptops, a high-capacity power bank adds 1-3 hours of use, not a full workday. It's emergency backup or top-up power, not a primary power source.
The Airline Limit
Power banks under 100Wh fly without restriction; between 100-160Wh requires airline approval. This practically limits travel-friendly laptop power banks to around 26,800mAh (approximately 99Wh at 3.7V).
This capacity provides roughly 1-3 hours of additional laptop runtime depending on your usage. For longer flights or work sessions, you'll need to manage power carefully or find seat power outlets.
Does Your Laptop Support USB-C Charging?
Not all laptops can charge via USB-C. Before buying a laptop power bank, verify your laptop supports USB-C Power Delivery charging.
Laptops That Support USB-C PD
Most modern ultrabooks and thin laptops support USB-C PD charging:
- All MacBooks from 2016 onwards
- Dell XPS series
- Lenovo ThinkPad X1 and recent ThinkPads
- HP Spectre and Elite series
- Microsoft Surface Pro and Laptop (USB-C models)
- Most Chromebooks
Laptops That Often Don't
Gaming laptops and older business laptops often don't support USB-C charging, even if they have USB-C ports. Their high power requirements exceed USB-C PD limits, and they typically require proprietary barrel-connector chargers.
Check your laptop's specifications or try connecting it to a USB-C PD charger (if available) to verify compatibility before purchasing a power bank.
Choosing the Right Power Bank for Your Laptop
For Ultrabooks (30-45W)
MacBook Air, Dell XPS 13, and similar thin laptops work well with 45-65W power banks. A 20,000-26,800mAh capacity provides 2-3 hours of additional runtime. These laptops are power-efficient enough that even slightly underpowered sources work acceptably.
For Standard Laptops (60-65W)
Most 13-14" professional laptops need 60-65W power banks for optimal charging. Look for power banks specifically advertising 65W USB-C PD output. These are common and reasonably priced.
For Large Laptops (87-100W)
MacBook Pro 16" and similar high-performance laptops need 87W+ power banks. These are less common and more expensive. A 60W power bank will charge these laptops but slowly, and may not keep up with heavy workloads.
If your laptop came with a high-wattage charger (87W+), consider a slightly lower-wattage power bank for travel (65W). It won't charge as fast but remains useful for topping up during light work, and you'll have more product options at better prices.
Cable Considerations
USB-C cables also have power ratings. A cable rated for 3A (60W) won't deliver 100W even with a capable power bank. For laptop charging:
- 60W laptops: Standard 3A USB-C cables work fine
- 65-100W laptops: Use 5A cables marked for 100W
- 100W+ laptops: Ensure cables are EPR-rated for higher power
The cable included with quality laptop power banks is usually appropriately rated. If using your own cable, check its specifications. Cheap cables may limit charging speed regardless of power bank capability.
Practical Usage Tips
Extend Runtime
When running on power bank power, reduce laptop power consumption:
- Lower screen brightness significantly
- Disable keyboard backlighting
- Close unnecessary applications
- Enable power saver mode
- Disconnect external devices
Charge While Sleeping
If you don't need to use your laptop, let it sleep or hibernate while charging from the power bank. Charging efficiency is much better when the laptop isn't simultaneously consuming power.
Top Up Strategy
Rather than draining your laptop battery before connecting the power bank, connect it early and use the power bank to extend total runtime. Keeping the laptop battery partially charged while the power bank provides power maximises your total working time.
For laptop-capable power bank recommendations, explore our product comparisons where we highlight models with the wattage output needed for laptop charging.