Can You Charge a Laptop with a Phone Charger?

It’s a common situation: your laptop battery is running low, but all you have on hand is your phone charger. Can that small charger actually power up your laptop? Or might it cause damage? Let’s clear up these questions.

Can a Phone Charger Provide Enough Power to Charge a Laptop?

In most cases, standard phone chargers don’t supply enough power to charge a laptop properly. Phones usually require between 5 to 20 watts, whereas laptops often need 30 to 100 watts or more, depending on the model.

Think of your laptop as a large vehicle needing a full tank of fuel, and the phone charger as a small gas can. You might add some fuel, but it won’t fill the tank quickly—or sometimes at all. Some phone chargers can charge a laptop very slowly or maintain its current battery level, but this varies widely.

For instance, Apple’s MacBook Pro chargers provide 61W or 96W, while most phone chargers deliver around 18W to 20W for fast charging Source: Apple Support. Using a 20W phone charger with a MacBook would result in very slow charging or no noticeable charge at all.

What Are the Differences Between Phone Chargers and Laptop Chargers?

Here’s how phone and laptop chargers differ:

Laptop chargers deliver higher voltages and current to meet the demands of larger batteries. Phone chargers are designed for smaller batteries and lower power consumption.

Is It Safe to Use a Phone Charger to Charge a Laptop?

Safety depends on compatibility. If both your phone charger and laptop support USB-C Power Delivery (PD), they can communicate to negotiate the correct voltage and current, making it generally safe to use the phone charger with your laptop.

However, if your laptop doesn’t support USB-C PD, or you use incompatible cables or adapters, risks include:

• Overheating of the charger or laptop
• Potential damage to the battery or internal components
• Failure to charge or even battery drain

For example, plugging a 5V phone charger into a laptop expecting 19V won’t provide enough power. In some cases, this mismatch could strain the charger or laptop hardware.

It’s also important to avoid cheap or uncertified chargers that may lack proper safety features.

In summary: Use chargers recommended by your laptop manufacturer, and if using a phone charger, ensure it’s a USB-C PD charger with adequate wattage for your laptop.

What Types of Phone Chargers Can Charge Laptops?

Not all phone chargers can effectively charge laptops. Only certain chargers—typically those supporting USB-C Power Delivery (PD)—can safely provide enough power.

USB-C Power Delivery (PD) Chargers

USB-C PD allows devices and chargers to negotiate voltage levels between 5V and 20V and adjust current accordingly. A phone charger with USB-C PD and sufficient wattage (usually 30W or more) can charge many laptops, especially newer models designed for USB-C charging.

For example, the Google Pixel 6’s 30W USB-C PD charger can charge some laptops at a slower rate Source: Google Support.

Quick Charge and Other Protocols

Other fast-charging protocols, like Qualcomm Quick Charge, are primarily designed for phones and may not be compatible with laptops. Always check your laptop’s charging specifications before using these chargers.

Conclusion

While it’s tempting to use your phone charger to juice up your laptop in a pinch, it’s not always practical or safe. If your phone charger supports USB-C Power Delivery and provides enough wattage, it might work, but expect slower charging.

To avoid potential damage or frustration, use chargers specifically designed for your laptop whenever possible.

References:

• Apple Support: About USB-C Power Delivery
• Google Support: Pixel Phone Charging
• USB Implementers Forum: USB Power Delivery Specification