Why does my iPhone charge slowly with some cables?

Your iPhone may charge slowly with some cables because the cable itself can limit how much power reaches the phone, or because the cable/connector is worn or damaged.

Common reasons include:

• Older or less capable cable/charger combinations: Some cable types and charger setups simply don’t support iPhone fast charging. For many older iPhones, fast charging typically requires a USB-C charger that supports USB Power Delivery, plus a compatible USB-C to Lightning cable. For iPhone 15 and newer, you generally need a USB-C to USB-C cable with a USB-C Power Delivery charger.
• Poor-quality or uncertified cables: Cheap third-party cables may not meet Apple’s accessory standards and can sometimes charge more slowly or unreliably.
• Thin or damaged wiring: If the cable’s internal wires are thin or have been damaged by repeated bending, more electrical resistance can reduce charging speed.
• Dirty or worn connectors: Lint, corrosion, dirt, or worn contacts on either end of the cable can interfere with a solid connection and slow charging.
• Low-power charger: Even a good cable will charge slowly if the charger itself doesn’t provide much power.