How Many Watts Should My Charger Be? | Match Wattage, Not Size

Your charger should meet or exceed your device’s required wattage, with 15W–30W for phones and 45W–100W for most laptops.

For the full breakdown, see our best 100 Watt Battery Charger guide.

Choosing a charger by how the plug looks rather than how much power it delivers is the easiest way to end up with a slow charge or a laptop that drains while plugged in. Matching wattage matters more than the USB-C shape, because that port is only a connector. The power your device pulls depends on what it asks for through USB Power Delivery.

What Does Wattage Actually Mean For Charging?

Wattage is the amount of power a charger can supply, calculated as voltage multiplied by current. A 20V/5A output equals 100W. This number tells you the charger’s ceiling, not what it forces into your device.

USB Power Delivery handles the negotiation between the charger and your device. When you plug in a 100W charger to a phone that wants 20W, the device requests only what it needs. When you plug a 20W charger into a laptop that wants 65W, the laptop takes what it can get and charges slowly, or loses ground while you work.

How Many Watts Do Different Devices Need?

The safest method is checking the label on your device’s original charger or its official specs page for the required input power. A charger that meets or exceeds that number is correct, as long as your cable is rated for it too.

Here’s what common device categories typically require:

• Phones and earbuds: 15W–30W is plenty for nearly all models. USB Type-C without USB PD tops out at 15W.
• Tablets: 20W–30W handles most tablets, including iPads and Android slates.
• Chromebooks and thin-and-light laptops: 45W is the common recommendation for this class.
• Standard laptops: 65W covers most mainstream models from Dell, HP, and Lenovo.
• Power-hungry laptops and docks: 100W or higher, using USB PD 3.1 Extended Power Range.

The USB Implementers Forum, which sets the standard, describes three power tiers. Standard USB-C without PD delivers 15W. USB PD 3.0, the current standard, supports up to 100W at 20V/5A. USB PD 3.1 goes further, enabling up to 240W using 28V, 36V, and 48V outputs. If you own a hefty workstation laptop, look for a charger with Extended Power Range support to get above 100W.

Why Your Cable Matters As Much As The Charger

A capable charger is only half the equation. The cable must be rated for the power level you’re pushing through it. Plugging a high-wattage charger into an under-rated cable creates a bottleneck, and for USB PD 3.1/EPR above 100W, you need a full-featured cable designed for that power tier.

Whether you’re charging a phone overnight or keeping a work laptop alive through long sessions, picking the right wattage involves one simple rule: check your device’s requirement, then buy a charger that meets or exceeds it without exceeding what your cable supports. If you’re in the market for serious power, our tested roundup of the best 100 watt battery charger options can point you to dependable picks.