USB-IF Power & Data Diagnostic

USB-C Charger, Cable E-Marker & Fast-Charge Bottleneck Checker

USB-C fast charging always negotiates down to the weakest link in the chain between your wall adapter, USB-C cable E-marker chip, and device PD controller. Select your three components to see exact negotiated wattage.

USB-C Wall Charger / Port

USB-C Cable Rating

Connected Device

Negotiated Peak Power60 W

Limiting Bottleneck3A Cable (60W)

E-Marker Chip Needed?Yes (>60W)

Bottleneck Detected: Your unmarked 3A USB-C cable lacks a 5A E-marker chip, capping your 100W charger at 60W (20V × 3A). Upgrade to a 100W/240W E-marked cord!

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Browse tested 65W–100W GaN blocks with live digital wattage displays.

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Why Every Cable Over 60W Needs an E-Marker IC

Under the official USB Power Delivery specification, standard USB-C cords without an electronic marker chip are strictly limited to 3 Amps at 20 Volts (60W)—even if plugged into a 140W MacBook brick! Reaching 100W (20V × 5A) requires a 5A E-marked cable, and reaching 140W–240W Extended Power Range (EPR) requires a 240W-rated EPR E-marked cord. Learn more in USB-C Ports & Cables Explained and USB-PD, PPS & Quick Charge Decoded.