{"id":1202,"date":"2026-05-13T01:38:34","date_gmt":"2026-05-13T01:38:34","guid":{"rendered":"https:\/\/edk-tech.net\/?p=1202"},"modified":"2026-05-13T04:00:32","modified_gmt":"2026-05-13T04:00:32","slug":"sd-card-speed-and-specs","status":"publish","type":"post","link":"https:\/\/edk-tech.net\/?p=1202","title":{"rendered":"SD Card \u2013 Speed and Specs"},"content":{"rendered":"\n<p><em>A complete reference for <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-alt-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SD card<\/a> types, speed classes, bus interfaces, and performance ratings.<\/em><\/p>\n\n\n\n<p>Secure Digital (SD) cards are widely used in cameras, phones, embedded systems, and portable electronics. Their performance depends on three major factors:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Capacity class<\/strong> (SD \/ <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-abbr-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDHC<\/a> \/ <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-abbr-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDXC<\/a> \/ <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-abbr-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDUC<\/a>)<\/li>\n\n\n\n<li><strong>Speed class<\/strong> (C, U, V, E)<\/li>\n\n\n\n<li><strong>Bus interface<\/strong> (Standard, High\u2011Speed, UHS\u2011I\/II\/III, Express)<\/li>\n<\/ul>\n\n\n\n<p>This guide explains each classification and how to choose the right card for your device.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Size<\/h2>\n\n\n\n<p>SD, <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-alt-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">miniSD<\/a>, <a href=\"https:\/\/edk-tech.net\/?glossary=secure-digital-card-sd-card\"\r\n                    class=\"yaw-glossary yaw-glossary-alt-link\"\r\n                    title=\"Secure Digital (SD)\"\r\n                    data-bs-toggle=\"popover\"\r\n                    data-bs-html=\"true\"\r\n                    data-bs-trigger=\"hover focus\"\r\n                    data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">microSD<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Storage Capacity Classes SD Card Capacity Classes<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Type<\/th><th>Capacity Range<\/th><\/tr><\/thead><tbody><tr><td><strong>SD (Secure Digital)<\/strong><\/td><td>Up to <strong>2 GB<\/strong><\/td><\/tr><tr><td><strong><abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDHC<\/abbr> (High Capacity)<\/strong><\/td><td><strong>&gt;2 GB to 32 GB<\/strong><\/td><\/tr><tr><td><strong><abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDXC<\/abbr> (Extended Capacity)<\/strong><\/td><td><strong>&gt;32 GB to 2 TB<\/strong><\/td><\/tr><tr><td><strong><abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDUC<\/abbr> (Ultra Capacity)<\/strong><\/td><td><strong>&gt;2 TB to 128 TB<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>Compatibility rule:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Devices that support <abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDXC<\/abbr> also support <abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDHC<\/abbr> and SD.<\/li>\n\n\n\n<li>Devices that support <abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDUC<\/abbr> support all previous types.<\/li>\n\n\n\n<li>Older devices may NOT support <abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDXC<\/abbr> or <abbr class=\"yaw-glossary-abbr\"\r\n                title=\"Secure Digital (SD)\"\r\n                data-bs-toggle=\"popover\"\r\n                data-bs-html=\"true\"\r\n                data-bs-trigger=\"hover focus\"\r\n                data-bs-content=\"&lt;p&gt;A removable flash memory card format used in cameras, mobile devices, embedded systems, and portable electronics. SD cards are defined by the SD Association and categorized by capacity, bus interface, and speed class. Capacity Classes: SD: Up to 2 GB&hellip;&lt;\/p&gt;\n\">SDUC<\/abbr>.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Write speed ratings<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Bus Speed Ratings (Data Transfer Speeds)<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Bus Type<\/th><th>Max Speed<\/th><th>Notes<\/th><\/tr><\/thead><tbody><tr><td><strong>Default Speed<\/strong><\/td><td>12.5 MB\/s<\/td><td>Legacy<\/td><\/tr><tr><td><strong>High\u2011Speed<\/strong><\/td><td>25 MB\/s<\/td><td>Widely supported<\/td><\/tr><tr><td><strong>UHS\u2011I<\/strong><\/td><td>50 MB\/s or 104 MB\/s<\/td><td>Single\u2011row contacts<\/td><\/tr><tr><td><strong>UHS\u2011II<\/strong><\/td><td>156 MB\/s (full\u2011duplex) \/ 312 MB\/s (half\u2011duplex)<\/td><td>Second row of pins<\/td><\/tr><tr><td><strong>UHS\u2011III<\/strong><\/td><td>312 MB\/s (full\u2011duplex) \/ 624 MB\/s (half\u2011duplex)<\/td><td>Rare<\/td><\/tr><tr><td><strong>SD Express<\/strong><\/td><td><strong>985 MB\/s+<\/strong><\/td><td>PCIe\/NVMe\u2011based<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>Important:<\/strong> Bus speed \u2260 real\u2011world write speed. Bus speed is the <em>maximum interface capability<\/em>, not guaranteed performance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Speed Class Ratings (C, U, V, E)<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Original Speed Class (C)<\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Class<\/th><th>Minimum Write Speed<\/th><\/tr><\/thead><tbody><tr><td><strong>C2<\/strong><\/td><td>2 MB\/s<\/td><\/tr><tr><td><strong>C4<\/strong><\/td><td>4 MB\/s<\/td><\/tr><tr><td><strong>C6<\/strong><\/td><td>6 MB\/s<\/td><\/tr><tr><td><strong>C10<\/strong><\/td><td>10 MB\/s<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Original Speed Class (C)<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">UHS Speed Class (U)<\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Class<\/th><th>Minimum Write Speed<\/th><\/tr><\/thead><tbody><tr><td><strong>U1<\/strong><\/td><td>10 MB\/s<\/td><\/tr><tr><td><strong>U3<\/strong><\/td><td>30 MB\/s<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">UHS Speed Class (U)<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">Video Speed Class (V)<\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Class<\/th><th>Minimum Write Speed<\/th><\/tr><\/thead><tbody><tr><td><strong>V6<\/strong><\/td><td>6 MB\/s<\/td><\/tr><tr><td><strong>V10<\/strong><\/td><td>10 MB\/s<\/td><\/tr><tr><td><strong>V30<\/strong><\/td><td>30 MB\/s<\/td><\/tr><tr><td><strong>V60<\/strong><\/td><td>60 MB\/s<\/td><\/tr><tr><td><strong>V90<\/strong><\/td><td>90 MB\/s<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Video Speed Class (V)<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">Express Speed Class (E)<\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Class<\/th><th>Minimum Write Speed<\/th><\/tr><\/thead><tbody><tr><td><strong>E150<\/strong><\/td><td>150 MB\/s<\/td><\/tr><tr><td><strong>E300<\/strong><\/td><td>300 MB\/s<\/td><\/tr><tr><td><strong>E450<\/strong><\/td><td>450 MB\/s<\/td><\/tr><tr><td><strong>E600<\/strong><\/td><td>600 MB\/s<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Express Speed Class (E)<\/figcaption><\/figure>\n\n\n\n<p>These are used for <strong>high\u2011end cameras, 4K\/8K video, and SD Express devices<\/strong>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Application Performance Class rating<\/h2>\n\n\n\n<p>Designates the minimum number of Input\/Output Operations per Second (IOPS)<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Class<\/th><th>Read IOPS<\/th><th>Write IOPS<\/th><\/tr><\/thead><tbody><tr><td><strong>A1<\/strong><\/td><td>1,500<\/td><td>500<\/td><\/tr><tr><td><strong>A2<\/strong><\/td><td>4,000<\/td><td>2,000<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>These ratings matter for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Smartphones<\/li>\n\n\n\n<li>Tablets<\/li>\n\n\n\n<li>Single\u2011board computers (Raspberry Pi)<\/li>\n\n\n\n<li>App storage and random access workloads<\/li>\n<\/ul>\n\n\n\n<p>A2 cards require host support to reach full performance.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Read speed rating<\/h2>\n\n\n\n<p>The read speed rating of an SD card is usually indicated by the number and data unit, i.e. MB\/s, that is printed on the front of the card (e.g., \u201c100 MB\/s\u201d).<\/p>\n\n\n\n<p><strong>Important:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Read speed is usually higher than write speed.<\/li>\n\n\n\n<li>Manufacturers advertise read speed because it looks better.<\/li>\n\n\n\n<li>Write speed is what matters for video recording.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Choosing the Right SD Card<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>For photography<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>U3 \/ V30<\/strong> minimum<\/li>\n\n\n\n<li><strong>UHS\u2011I or UHS\u2011II<\/strong> depending on camera<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>For 4K video<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>V30 or V60<\/strong><\/li>\n\n\n\n<li>Avoid C10\/U1 cards<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>For 8K video<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>V60 or V90<\/strong><\/li>\n\n\n\n<li>Prefer UHS\u2011II or SD Express<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>For smartphones \/ app storage<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>A2<\/strong> recommended<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>For Raspberry Pi<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>A1 or A2<\/strong><\/li>\n\n\n\n<li>Avoid cheap unbranded cards<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>A complete reference for SD card types, speed classes, bus interfaces, and performance ratings. Secure Digital (SD) cards are widely used in cameras, phones, embedded systems, and portable electronics. Their performance depends on three major factors: This guide explains each classification and how to choose the right card for your device. Size SD, miniSD, microSD [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"pagelayer_contact_templates":[],"_pagelayer_content":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[23],"tags":[],"class_list":{"0":"post-1202","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-knowledgebase"},"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/peQefU-jo","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/posts\/1202","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/edk-tech.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1202"}],"version-history":[{"count":3,"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/posts\/1202\/revisions"}],"predecessor-version":[{"id":1209,"href":"https:\/\/edk-tech.net\/index.php?rest_route=\/wp\/v2\/posts\/1202\/revisions\/1209"}],"wp:attachment":[{"href":"https:\/\/edk-tech.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1202"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/edk-tech.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1202"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/edk-tech.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1202"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}