Your 120W cable is not charging at 120W — here is why

Charging speed is decided by the slowest of three things: the charger, the phone, and the cable. Most people check the first two.

The cable is a ceiling, not a pipe

A USB-C cable is rated for a maximum power. Put a 60W cable between a 70W charger and a phone that can take 70W, and you charge at 60W. Nothing warns you. It simply charges slower than you paid for.

What the ratings actually mean

• Up to 60W — 20V at 3A. The default for a plain USB-C cable, and the most common thing in a drawer.
• 100W — 20V at 5A. Carrying more than 3A requires thicker conductors and a small chip in the connector, the e-marker, that tells the charger the cable can take it. A cable without one is held to 60W by design.
• 240W — the newer USB PD 3.1 tier, up to 48V. Needed for high-draw laptops, overkill for a phone, and harmless to use with one.

Our Romoss 100W USB-C cable is Rs 1,800 and covers any phone and most laptops. The Anker Zolo 240W braided cable is Rs 2,500, rated for 10,000+ bends, with a 5.8mm connector that actually fits through a thick case — the detail that kills more cables than wattage ever does.

USB-A plays by different rules

USB Power Delivery runs over USB-C. A USB-A port cannot do it. When you see a USB-A cable advertised at high wattage — our Xiaomi 120W 10A cable at Rs 1,799, for instance — that is a manufacturer's own fast-charge standard, and it hits its peak only with that manufacturer's charger and that phone. On anything else it still works, just at ordinary speeds.

Fast at charging is not fast at data

These are separate wires in the same cable. A cable can carry 100W and still move files at USB 2.0 speed — 480 Mbps — because charging capacity and data capacity are specified independently. Our Romoss 100W cable is exactly that, and for charging it makes no difference at all. It only matters if you are moving large files off a phone or running a display.

A note on the Apple cable

The Apple USB-C to USB-C cable in the box with most iPhones is rated to 60W. That is plenty for any iPhone. If you are using it with a laptop, it is the ceiling you are hitting.

What to buy

• Phone only: any 60W-plus USB-C cable is enough. Buy for build quality, not wattage.
• Phone and laptop on one cable: 100W.
• A manufacturer's headline fast charging (Xiaomi, Oppo, Realme, OnePlus): use the cable that came with the phone, or that brand's own.

If you are unsure which your phone needs, message us on WhatsApp with the model and we will tell you — including when the answer is that the cable you already own is fine.