# Article: Why are some Thunderbolt 3 cables 20Gbps and some 40Gbps? **URL:** \ **Category:** Cables, AV Splitters, AV Extenders\ **Created:** [September 27, 2021, 12:54pm UTC](https://community.startech.com/t/article-why-are-some-thunderbolt-3-cables-20gbps-and-some-40gbps/787 "2021-09-27T12:54:46Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![malcolm](https://yyz2.discourse-cdn.com/flex012/user_avatar/community.startech.com/malcolm/32/17_2.png) [@malcolm](https://community.startech.com/u/malcolm)\ **Post date:** [September 27, 2021, 12:54pm UTC](https://community.startech.com/t/article-why-are-some-thunderbolt-3-cables-20gbps-and-some-40gbps/787/1 "2021-09-27T12:54:46Z")
Although the Thunderbolt™ 3 standard is capable of data transfer speeds up to 40Gbps, not all TB3 cables can support this bandwidth. For example, some cables over a certain length are only capable of data transfer speeds up to 20Gbps. To confirm the capability of your Thunderbolt 3 cable, refer to the information provided by the manufacturer. [StarTech.com](http://StarTech.com) lists the capabilities of the Thunderbolt 3 cables on the individual product pages. There are two different Thunderbolt 3 cable symbols: 20 Gbps Thunderbolt 3 Cable ![20-Gbps.jpg](https://canada1.discourse-cdn.com/flex012/uploads/startester/original/1X/72c1c4bd9ee9f2f124d42b4ab4dd271f46586ec2.jpeg) 40 Gbps Thunderbolt 3 Cable ![40-Gbps.jpg](https://canada1.discourse-cdn.com/flex012/uploads/startester/original/1X/c7b491dffe3fd2892b27bb525c6b2fd4cc69c9a9.jpeg)