Quick Answer
Class 10 and U1 both guarantee 10MB/s minimum write, covering 1080p video. U3 and V30 both guarantee 30MB/s, covering 4K at standard bitrates. V60 guarantees 60MB/s for high-bitrate 4K. V90 guarantees 90MB/s for 6K and 8K. These are minimum write speed floors, not top speeds.
The Speed Class Hierarchy Explained 🔬
SD card speed classes developed over time as camera technology demanded faster storage. The original Speed Class uses a C-shaped icon with a number inside: Class 10 (C10) is the minimum you should accept on any card today, guaranteeing 10MB/s write. The UHS system added two tiers: U1 (the number 1 inside a U shape) matches Class 10 at 10MB/s minimum. U3 (the number 3 inside a U shape) guarantees 30MB/s minimum and is the threshold for 4K video. The Video Speed Class arrived specifically for video workflows: V6 guarantees 6MB/s, V10 guarantees 10MB/s, V30 guarantees 30MB/s, V60 guarantees 60MB/s, and V90 guarantees 90MB/s. Each higher tier is an increment in guaranteed minimum sustained sequential write speed under load.
What Each Class Covers in Practice 🎬
C10 and U1 at 10MB/s handle 1080p at 30fps comfortably and 4K only at very low bitrates below 80Mbps. U3 and V30 at 30MB/s minimum cover 4K at up to roughly 240Mbps with margin, making them the sweet spot for most consumer cameras. V60 at 60MB/s handles 4K at 400Mbps to 480Mbps, covering All-Intra formats on semi-pro bodies like the Lumix S5 II. V90 at 90MB/s is required for 6K RAW and 8K on professional cinema bodies. Note that UHS-I tops out at 104MB/s theoretical throughput while UHS-II reaches 312MB/s; the bus standard determines the maximum possible speed while the V-class determines the guaranteed minimum. A V30 card can be either UHS-I or UHS-II.
Shopping for SD Cards in South Africa: What the Labels Mean 💰
In the South African market, cards at the R100 to R200 price point are typically C10/U1. Cards from R300 to R550 for 128GB carry U3/V30 ratings and cover virtually all 4K camera use cases. V60-rated cards start around R900 to R1,400 for 128GB. V90 cards for professional cinema formats reach R2,500 to R4,000 for 128GB in UHS-II format. For the vast majority of South African photographers and videographers using consumer mirrorless bodies, DSLR hybrids, or entry prosumer cameras, the R300 to R550 UHS-I U3/V30 128GB card is the practical standard that covers all everyday 4K needs without overpaying.
Match the V-Class to Your Camera Mode, Not the Camera Body ⚡
A single camera body can require different V-class cards for different recording modes. A Sony A7 IV shooting 4K Standard at 100Mbps works perfectly with V30. The same body shooting 4K All-Intra at 200Mbps needs V60 for comfortable margin. Read your camera manual's card recommendations section for each recording mode.
FAQ
Is U3 the same as V30?
They guarantee the same 30MB/s minimum write speed but come from different labelling systems. U3 is from the UHS Speed Class framework; V30 is from the Video Speed Class framework. Both markings on one card mean the same guarantee stated twice.
Does the speed class affect how fast files transfer to a PC?
No. Speed class governs write speed during recording. Read speed (how fast the card transfers to a PC via a card reader) is a separate spec and is often quoted as the headline number on the packaging.
Can I use a V90 card in a camera that only needs V30?
Yes. Higher V-class cards are backward compatible. A V90 card in a V30-capable camera operates at full V30 speeds and above. You simply pay for performance your camera cannot fully exploit in its standard modes.
Confused by speed class labels at checkout? Browse SD cards at Evetech filtered by capacity and speed class to find the right U3/V30 or V60 option for your specific camera body and budget.
