In reply to rem.

The guide deliberately uses watts instead of amps, and here's why: the 1A vs 2A distinction you're thinking of was the key differentiator in the old USB-A world, where voltage was fixed at 5V. In that era, amps were the only variable (5V × 1A = 5W iPhone brick vs 5V × 2.1A ≈ 10W iPad brick).

With USB-C Power Delivery — which is everything in this guide — both voltage and amperage are variable. A 30W charger might deliver 15V × 2A or 9V × 3.3A, depending on what the device negotiates. The device controls the conversation, not the charger. So watts is the only stable number to compare across chargers and devices. Amps alone would actually be misleading because the same amperage at different voltages means very different charging speeds.

Short version: you're not wrong about the physics, but USB-C abstracted amps away from the user. Watts is the whole story now.