{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-20",
  "slug": "sd-speed-class",
  "term": "SD speed class",
  "aliases": [
    "UHS Speed Class",
    "Video Speed Class",
    "SD Express Speed Class"
  ],
  "definition": "An SD speed class specifies a minimum sequential-access performance level under the access rules and operating conditions of its class family.",
  "note": "C, U, V and E marks describe performance classes, while UHS-I, UHS-II and SD Express describe interfaces. Match the host's class family and required level: equal numeric throughput in different families does not establish equivalent host support [classes].\n\nE150, E300, E450 and E600 specify 150, 300, 450 and 600 MB/s minimum read/write performance under SD Express Speed Class conditions. These conditions include host access rules and power and thermal management, rather than a promise for arbitrary workloads [express].",
  "related": [
    "sd-capacity-family",
    "sd-application-performance-class",
    "sd-express"
  ],
  "citations": [
    {
      "id": "classes",
      "title": "SD Association: speed classes, host matching and free allocation units",
      "url": "https://www.sdcard.org/developers/sd-standard-overview/speed-class/",
      "accessed": "2026-10-20"
    },
    {
      "id": "express",
      "title": "SD Association: SD Express Speed Class, SD 9.1 whitepaper, October 2023, pages 7-9",
      "url": "https://www.sdcard.org/wp-content/uploads/2023/10/SDExpressSpeedClassSD9_1Specification.pdf",
      "accessed": "2026-10-20"
    }
  ]
}