You bought a fast charger. The phone still takes three hours. Before replacing anything, work through this list in order — it is roughly the order of how often each cause turns out to be the real one.

1. The cable, not the charger

This is the single most common answer and the one almost nobody checks, because every USB-C cable looks the same. Inside, they are not. A cable built only for 15W will hold the whole connection at 15W even when plugged into a 65W charger. Power Delivery negotiates down to whatever the weakest link allows.

The quick test: borrow a cable you know is good — the one that came with a laptop, for instance — and try the same charger with it. If the speed jumps, you found it.

Free cables that came in the box with an accessory, cables from a hotel lost-and-found drawer, and anything sold in a three-for-five-dollars bin are the usual suspects.

2. You are charging through a USB-A port

If the end that goes into the charger is a flat rectangle, you are on USB-A. Almost all USB-A ports — in cars, on laptops, on older wall bricks, in hotel nightstands — cap out around 12W. Some are as low as 5W.

The connector shape tells you the ceiling before you plug anything in. Fast charging on a modern phone requires USB-C on both ends, or a USB-A port explicitly rated for Quick Charge.

3. Two devices are sharing one charger

A 30W dual-port charger supplies 30W in total, not 30W per port. Plug in earbuds alongside the phone and the phone's share drops. Some chargers split it evenly, others prioritise the USB-C port — either way you are not getting the full figure.

If you need both devices at speed, that is an argument for two chargers, not a bigger one.

4. The battery is above 80 percent

Every modern phone slows charging deliberately once the battery passes roughly 80 percent. Lithium cells take the last fifth slowly to avoid heat and wear. A phone that goes 0 to 50 percent in twenty minutes and then takes an hour for the last 20 percent is behaving exactly as designed.

The same applies to features like Optimised Battery Charging, which intentionally pauses at 80 percent overnight and finishes just before your alarm.

5. The phone is warm

Heat is the enemy of both charging speed and battery lifespan, so phones throttle charging when they get warm. Charging inside a thick case, in direct sun, on a car dashboard, or while navigating with the screen at full brightness all trigger it.

Take the case off and move it out of the sun before you conclude the charger is faulty.

6. The port is dirty

Pocket lint compacts into the bottom of a USB-C port over months and stops the connector seating fully. The symptoms are distinctive: the cable feels loose, charging cuts in and out when the phone moves, or it only works at one angle.

Power the phone off and use a wooden toothpick or a plastic spudger. Not a metal pin — the contacts at the bottom of the port are easy to bend and expensive to fix.

The practical fix

For most people the answer is a 30W USB-C charger and a cable rated for 60W. That combination charges any current phone at its maximum rate, and the cable will not be the bottleneck for a tablet or a light laptop either. Anything beyond that is a laptop purchase, not a phone one.

More detail on the numbers: USB-C charging wattage guide. Or go straight to wall chargers and charging cables.