The Three Golden Rules of Compatibility

When looking for a replacement, you must check the "Output" section on your old power brick or the "DC Input" sticker on the bottom of your laptop.

• Voltage ($V$): Must Match Exactly. If your laptop requires 19.5V, you must use a 19.5V adapter. A difference of more than 5% can fry the internal circuits (if too high) or cause instability (if too low).

• Amperage ($A$): Must be Equal or Higher. If your laptop needs 3.33A, using a 4.62A adapter is perfectly safe; the laptop will only "pull" the power it needs. However, using a 2.31A adapter will cause the charger to overheat and likely fail.

• Wattage ($W$): Must be Equal or Higher. Wattage is simply $Voltage \times Amperage$. A 90W charger can safely replace a 65W charger, but a 45W charger will be too weak for a 90W machine.

2. Identifying the Connector (Tip Size)

Even if the power specs match, the plug must fit. The most common types in 2026 are: