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Will this USB-C charger work with my laptop?

It works at full speed if it gives at least the watts on your laptop’s own charger and the cable can carry them. Below that, most laptops charge slowly, and under 27 W many don’t charge at all.

Laptop charger checker

USB-C · power banks · car chargers

1 · Your laptop

We use the adapter wattage Apple recommends for each model. Not sure which you have? Apple menu › About This Mac. System Information › Power also shows the watts of the charger plugged in now.

2 · The charger you want to use

Use the total output on the charger, like “65W” or “100W max”.

How to find the numbers

Your laptop's number is the wattage on the charger it came with. Look for "65W" or similar on the brick. If you only see output volts and amps, multiply them: 20 V at 3.25 A is 65 W. Lost the charger? The input rating is on the label under the laptop, or in the manual. On a Mac, System Information › Power shows the wattage of whatever is plugged in.

Still not sure? The checker can assume 65 W, which Dell lists as the best fit for most of its USB-C laptops. That's a guess, and the result says so.

The charger's number is its total USB-C output, often written as "PD 65W" or "100W max". On a charger with two or more ports, the label usually lists the watts per port when more than one is in use, like "65W + 30W". That shared figure is the one that matters if your phone is plugged in too, and the checker asks for it on chargers of 60 W and up.

The cable matters more than people expect. A USB-C cable without an e-marker chip carries at most 3 A, which is 60 W at 20 V. To go higher you need a cable rated for 100 W (5 A) or 240 W. Certified cables carry a 60 W or 240 W logo on the plug or packaging.

What the verdict means

The checker compares what reaches the laptop with what its own charger gives. The weakest link sets the number, whether that's the charger, a shared port, a hub or the cable.

VerdictPower that reaches the laptopWhat you'll see
Full speedIts own charger's wattage or moreCharges as normal. A bigger charger is fine; the laptop only draws what it needs.
Close to full85 to 99% of itLittle difference except under heavy load. Some Windows laptops still flag a slow charger.
Charges slowlyHalf or moreCharges well when asleep. Under heavy load it may only hold its level.
Very slowUnder half, 27 W or more on WindowsCharges mostly when asleep or off. Drains while you work.
May not charge15 to 26 W on a Windows laptop or ChromebookBelow Dell's 27 W minimum. Many laptops won't charge; some charge only while off.
Won't chargeUnder 15 W, or no USB-C chargingNothing, or a warning. Barrel-only laptops can't take USB-C power at all.

The bands are our own way of grouping results. The rules behind them: Dell says a lower-wattage adapter charges the battery more slowly, shows a warning, and in some cases lets the battery drain while plugged in; ASUS says a "Slow Charger" message means the charger's wattage may be too low; without USB Power Delivery a USB-C port gives 5 V at 3 A (Dell, ASUS, Adafruit, checked Oct 24, 2026).

Dell gives the clearest numbers. It lists 27 W as the minimum to run and charge most of its USB-C laptops, with 60 to 65 W as the best fit and 45 W or more for some models with dedicated graphics.

MacBook charger wattages

Apple says you can charge any Mac laptop from any USB-C charger, higher or lower wattage, but recommends at least the wattage below for the best charging. Fast charge gets recent models to about 50% in around 30 minutes, and it needs a bigger adapter.

ModelRecommended adapterFast charge with
MacBook Air 13-inch (2022 or later)30 W67 W or more
MacBook Air 15-inch35 W dual-port70 W or more
MacBook Air (2018 to 2021)30 WNot listed
MacBook Pro 14-inch (2021 or later)67 W, 70 W or 96 W96 W or 140 W
MacBook Pro 16-inch (2021 or later)140 W140 W with MagSafe 3, or a 240 W USB-C cable (Nov 2023 and later)
MacBook Pro 16-inch (2019)96 WNot listed
MacBook Pro 15-inch (2016 to 2019)87 WNot listed
MacBook Pro 13-inch (2016 or later)61 WNot listed

Apple: Use a power adapter with your Mac, and Fast charge your MacBook Air or MacBook Pro, checked Oct 24, 2026.

Power banks, car chargers and gaming laptops

A power bank or car charger follows the same rules as a wall charger. What counts is its USB-C PD output in watts, not its capacity. A 20,000 mAh bank that puts out 20 W may not charge a 65 W laptop at all, while a 100 W bank of the same size charges it at full speed.

For flying, the FAA allows spare lithium-ion batteries and power banks up to 100 Wh each in carry-on bags only. Banks from 101 to 160 Wh need airline approval, two at most. Airlines can set tighter limits, so check yours before you fly.

Most banks list mAh, not Wh. To convert, multiply by the cell voltage and divide by 1,000. At the usual 3.7 V, a 20,000 mAh bank is about 74 Wh and fine to carry on, while 30,000 mAh is about 111 Wh and needs airline approval. If the bank prints its Wh, go by that.

Gaming laptops are the exception to "any big enough charger works". Many take power only through a barrel plug. Those that charge over USB-C usually cap it well below their barrel charger. ASUS suggests 65 W or 100 W USB-C chargers for light use without heavy CPU or GPU work. Lenovo's Legion Pro 7 manual says its 140 W USB-C port isn't the main power input, and on USB-C the laptop "may not operate at its full capacity" while charging slows or stops. For games, use the barrel charger.

The mistakes that slow charging down

The usual one is the cable. A 100 W charger on the thin 60 W cable from a phone box stops at 60 W, and nothing on the charger tells you. Above 100 W it gets stricter: USB PD 3.1 Extended Power Range uses 28, 36 and 48 V for 140, 180 and 240 W, and the charger, the 240 W cable and the laptop all have to support it.

The second is sharing. Apple's 35 W dual adapter gives up to 17.5 W each to a Mac and an iPhone, so a MacBook Air that charges fine alone slows down once the phone goes in. Apple says the power goes to each device by what it needs, though, and bigger multi-port chargers often leave the laptop far more than half. The label shows the split.

The third is hubs and docks. Dell says a pass-through hub keeps at least 15 W for itself and whatever is plugged into it, so a 65 W charger through a hub leaves about 50 W for the laptop. If you're shopping for a laptop that charges from one small charger, the laptop finder can help, and the battery health check tells you if a short runtime is the battery rather than the charger.

Questions people ask

Can I use a higher-wattage charger on my laptop?

Yes. With USB Power Delivery the laptop and charger agree on the power before it flows, and the laptop draws only what it needs. Apple says any USB-C charger, higher or lower wattage, can charge a Mac.

Can a phone charger charge my laptop?

Often, but slowly. A 20 W phone charger on a 65 W laptop gives under a third of the power it expects, so it charges mostly while the laptop is asleep. Under 27 W many laptops won't charge at all. Dell says a phone charger "may take several hours to slowly charge a computer that is turned off".

Why does my laptop say slow charger?

The charger, cable, hub or shared port is giving less than the laptop's own charger. Dell and ASUS both show this warning when the wattage is lower than recommended. Check each link with the tool above.

Do I need a special cable for a 100 W charger?

Yes. Above 60 W the cable needs an e-marker chip rated for 5 A. Look for 100 W or 240 W on the cable or its packaging. For more than 100 W you need a 240 W cable.

Can I take a laptop power bank on a plane?

In the US, yes, in your carry-on, if it's 100 Wh or less. From 101 to 160 Wh you need airline approval. Power banks are never allowed in checked bags (FAA). A 20,000 mAh bank is about 74 Wh at 3.7 V.

Sources