How many watts does your phone actually need?
22 September 2026
The big numbers on charger boxes mean less than you would think. What separates a charger's rating from what your device takes — and why the cable matters.
The number on a charger is the most it can give, not what your device will take. The device decides; the charger agrees.
Three things set the speed, and the weakest one wins
- What the charger can supply
- What the device will accept
- The cable in between
Which is why people buy a high-wattage charger and notice nothing: the old cable will not carry it, so the charging stays exactly as it was.
Rough numbers worth knowing
- A recent phone: usually accepts somewhere between 20W and 45W
- A tablet: close to a phone, sometimes a little higher
- A thin laptop: starts around 65W and can want more
- Earbuds and wearables: always under 20W
One port or two
A two-output charger charges two devices at once, but the power is split — the headline figure is always for a single device alone. If what you care about is one phone charging fast, a single port at full power beats two sharing it.
In a car it is different
Wireless charging in a car is always slower than wired — around 15W on common units. What you get back is not threading a cable on every trip. If maps run the whole way, the difference between 15W and nothing matters more than the difference between 15W and 66W.
The practical version
Buy a charger that covers your most demanding device, and a cable that will carry it. Headroom above that does no harm, but it is not what you are paying for.
And where wireless charging sits in all this
Outside the comparison. 15W wireless does not measure against 30W wired — the two systems measure different things, and part of the wireless figure becomes heat before it reaches the battery. In practice: wireless for overnight and for a desk, a cable when you are in a hurry.
Common questions
- Does a more powerful charger always charge my phone faster?
- No. A phone draws only what it accepts. If it accepts 25W, a 140W charger gives it 25W — exactly as a 30W one would.
- Does the cable affect charging speed?
- Yes, a lot. A cable that cannot carry the power makes a strong charger pointless — it is the most common reason a new charger seems to change nothing.
- Why is wireless charging in a car slower?
- Wireless loses some energy as heat and sits around 15W on common units, against higher figures for wired. What it buys you is not connecting a cable on every trip.
