Charging wattage explained: 5W to 100W

What a watt actually is

Charging power is measured in watts, and watts are simply volts multiplied by amps. Volts is the electrical "pressure," amps is the flow, and watts is the two together — the total amount of energy a charger can deliver each second. A higher number means a device can charge faster, up to the limit the device itself allows.

That last point matters: a phone that accepts a maximum of 27W will draw 27W from a 20W charger's ceiling and no more from a 100W one. A bigger charger never forces more power into a device than it's designed to take. It just means one charger can serve many devices well.

Roughly how much your devices want

• Earbuds, smartwatches, small accessories: 5W is plenty.
• Phones: 20–30W covers fast charging for almost every current model.
• Tablets: 20–45W, depending on size.
• Laptops: 60W for lighter ultrabooks, 100W for larger or more powerful machines.
• Multiple devices at once: add up what each needs, and choose a charger or station that can deliver the total.

Why "fast charging" varies

Fast charging isn't one standard. USB Power Delivery (PD) is the common one, and a newer extension called PPS lets the charger fine-tune voltage in small steps to charge efficiently and stay cool. A device and charger have to speak the same standard to hit top speeds, which is why the right charger can nearly halve a phone's charge time while the wrong one trickles.

Bigger isn't wasteful

There's a common worry that a 100W charger will "overcharge" a phone or waste power. It won't. The device negotiates exactly what it needs, and a good charger draws very little when nothing's charging. Buying a little more headroom than you need today means the same charger still works when you upgrade your laptop next year.

Charging several things at once

Where wattage catches people out is multi-device charging. A charger or station shares its total output across everything plugged in, so a "65W" charger running three devices isn't giving each of them 65W — it's dividing that budget, often unevenly and by priority. If you routinely charge a laptop plus a phone plus earbuds together, add up what each wants at full speed and choose a total comfortably above the sum, so nothing drops to a crawl when the ports are full. This is the single most common reason a charger that "should be powerful enough" charges slowly: it's fine for one device but stretched across four. When you're buying for a desk or a family, size for the busy moment when everything's plugged in at once, not for a single device in isolation.

How KORD lists it

Every KORD charger and adapter shows its wattage in the name — a "30W" charger genuinely delivers up to 30W, tested to that figure rather than an optimistic sticker. If you tell us what you're charging at hello@kord.nz, we'll recommend the right size rather than the biggest one.