What SD Card for 4K Vlogging? V30 vs V60 vs V90, UHS and CFexpress Explained

Last updated: October 2026

Ask ten vloggers what SD card for 4K vlogging they use and you will get ten confident answers, most based on the biggest number printed on the card. That number is the wrong place to start: it is a best case read speed from a lab test, not the steady write speed your camera needs. This guide covers what actually decides if a card keeps up: sustained write speed, bitrate maths, the V classes, the UHS bus, CFexpress, and habits like formatting in camera.

The big number on the front is a read speed, not a promise

Read and write are different jobs. Reading happens when you copy footage to a computer, in short, fast bursts, so a peak figure looks great on a label. Writing video is the opposite: a steady stream the card has to swallow continuously. If the card slows while it reorganises its internal storage, the camera buffer fills and recording stops.

Sustained write speed is the figure that matters, and honest makers publish it in the full specifications, often well below the headline. A card shouting 170 MB/s might sustain 60 to 90 MB/s in writing. A cheap card with the same headline might sustain far less. That is why the guaranteed minimum, the video speed class below, beats any marketing number.

The bitrate maths: divide by eight, then add headroom

There are 8 bits in a byte, so 100 Mbps of video is 12.5 MB/s landing on the card. The table works it through for common modes. Bitrates vary between brands and codecs, so check your camera menu for the exact figure. Our guide to vlogging camera settings explained shows where bitrate sits among the other recording settings.

Headroom matters because the class figure is a minimum, and real cards dip as they fill and warm up. One class above the minimum costs little and removes a whole category of failures. Still choosing the camera? Our roundup of the best mirrorless camera for vlogging lists each body recording modes, and the best vlogging equipment for beginners guide shows where cards sit in a first kit.

Capacity: how much footage fits on a card

Work from gigabytes per hour rather than the size printed biggest on the packet. The rate doubles and halves with the bitrate, so a card that feels endless on a talking head vlog can run dry before lunch on a 4K60 travel day. Formatted capacity is always a little below the number on the label, which is why the times below are rounded down.

One big card or two smaller ones? Two 128 GB cards cost a little more than a single 256 GB card and buy you a failure plan: a card that dies holds half a day hostage instead of the whole shoot, and one card can go to the edit while the other keeps filming. Vloggers shooting once only days, a wedding, a launch, a trip that will not repeat, usually split capacity across cards for exactly that reason. If you film short clips at home and offload the same evening, the single big card is the simpler buy and this does not matter.

Speed classes decoded: the V, U and A markings

• Video Speed Class (V6 to V90). The rating written for video: a minimum sustained write speed in MB/s, tested as a continuous stream. Match this one against your bitrate maths.
• UHS Speed Class (U1 and U3). An older rating with the same idea: U1 guarantees 10 MB/s, U3 guarantees 30 MB/s, so U3 and V30 on one card say the same thing twice. U1 only cards suit Full HD, not 4K.
• Application Performance Class (A1 and A2). This rates random operations per second, the pattern phones use running apps from a card. Video is one sequential stream, so A2 is not a reason to pay more for camera use.

Two more labels describe capacity rather than speed. Cards up to 32 GB are marked SDHC, and cards from 64 GB up are marked SDXC. The split only bites with older cameras: a body from the SDHC era may refuse an SDXC card outright, whatever its speed class. Every card sold for 4K vlogging today is SDXC, and every current vlogging camera reads it.

An old plain Speed Class number in a circle, such as Class 10, topped out at 10 MB/s and predates 4K. MicroSD cards carry the same ratings, which is why the best drones for vlogging and action cameras record 4K to microSD happily, following the same maths.

UHS-I and UHS-II: what the second row of pins buys

The bus is the road, the speed class is the guaranteed pace of the traffic. A V90 card needs the wider road: no UHS-I card can sustain 90 MB/s inside a 104 MB/s ceiling once overhead is counted. UHS-I cards top out around V30, and every V60 or V90 card is UHS-II, shown by two rows of contacts.

Compatibility runs one way. A UHS-II card works in a UHS-I slot, but falls back to UHS-I speeds, because the camera cannot see the second row of pins. Check your camera specifications for slot type, not slot shape, since both cards share the same outline. For vlogging at 100 to 200 Mbps, UHS-I V30 is honestly enough. UHS-II earns its place with high bitrate modes, photo bursts, or fast offloads.

One expectation to set straight: a faster card never makes the picture better. The camera writes the same data either way, so a V90 card records identical footage to a V30 card in any mode both can sustain. What the faster card changes is which modes the camera will unlock, how quickly a burst of stills clears, and how fast a full card empties into your computer through a matching UHS-II reader. Buy it for access and time, not for quality.

CFexpress Type A and Type B, in plain terms

CFexpress sustained write speeds run into hundreds of megabytes per second, the strongest passing 1,000 MB/s. That headroom unlocks top flagship modes: high resolution video, high frame rates at high bitrates, and modes the menu greys out with only an SD card inserted. If a mode is locked, the manual will usually say CFexpress is required. That is a hardware limit, not an upsell.

Type A is compact, and some cameras use a combined slot that accepts Type A or SD. Type B is the bigger card used by other brands. Neither fits the other slot. A Type C exists too, but not in vlogging cameras. Confirm your camera type first: the names differ by one letter and the cards look similar in photos. Most vloggers do not need CFexpress: at 4K30 or 4K60 in standard codecs, SD covers it for less per gigabyte. Treat CFexpress as a key to specific modes.

CFexpress also has its own version of the V class, called VPG, short for Video Performance Guarantee. A VPG200 card promises a sustained write of at least 200 MB/s, and a VPG400 card at least 400 MB/s: the same idea as V30 or V90, with bigger numbers. Not every CFexpress card carries a VPG mark, because the rating is optional. When a camera mode names a VPG figure in the manual, treat it the way you treat a V class, as a floor the card must hold for the whole take, not a peak it touched once in a test.

What popular vlogging cameras actually ask for

General rules only take you so far, so here is how the requirements land on the cameras vloggers actually buy. These are the patterns from the makers’ own media tables. Your manual’s table, for your firmware, stays the final word.

• Sony ZV-E10. One SD slot, UHS-I. Its 4K modes top out at 100 Mbps, so a genuine V30 card covers every mode the camera offers. Money spent on UHS-II here buys offload speed only.
• Sony A7 IV, FX30 and a7S III. Both slots accept SD UHS-II or CFexpress Type A. Standard 4K runs happily on V60 SD cards, the all-intra XAVC S-I modes call for V90 SD or CFexpress Type A, and the highest frame rate modes on the a7S III are CFexpress only.
• Canon EOS R50. A single UHS-I slot and 4K bitrates a V30 card handles with room to spare. No mode on this body needs more.
• Canon EOS R10. A UHS-II slot, and 4K60 modes whose bitrates pass the V30 ceiling. V60 is the card to buy, and it opens every mode.
• Canon EOS R6 Mark II. Two UHS-II SD slots. Its 4K60 modes also run past the V30 guarantee, so V60 is the sensible floor and V90 keeps comfortable headroom.
• Canon EOS R5. One CFexpress Type B slot and one SD UHS-II slot. The 8K modes and 4K120 record to CFexpress; the SD slot covers the standard 4K modes on V60 or V90.
• Panasonic GH6 and GH7. CFexpress Type B plus SD UHS-II. ProRes recording is a CFexpress job, while the SD slot handles the compressed codecs, with V90 wanted at the highest bitrates.
• Fujifilm X-S20 and X-H2S. The X-S20 takes one UHS-II SD card, and its higher bitrate modes want V60 or better. The X-H2S adds a CFexpress Type B slot and reserves its ProRes modes for it.
• GoPro, DJI Osmo Pocket and drones. microSD territory. V30 covers standard 4K on current models, and the makers publish approved card lists, because some bargain microSD cards carry a V30 print they cannot hold. Check the list before a trip, not after a failed day.

Notice what no entry on this list says: no camera needs a faster card than its top mode demands, and none rewards one either. Match the fastest mode you will genuinely use, keep one class of headroom above it, and put the savings toward a second card.

Two slots, three useful ways to use them

Backup (simultaneous) recording writes every clip to both cards in real time. If one card fails, corrupts or gets lost, the take survives on the other. The costs: cards are consumed at twice the rate, and in many cameras the pair runs at the speed of the slower slot, so a UHS-I second slot can cap your modes. For paid work, most creators accept that.

Relay recording treats both cards as one long tank: card one fills, then recording rolls to card two without stopping you. This suits long interviews and travel days where swapping cards means missing moments. Our guide on how to start a travel vlog covers the wider routine for shooting away from home, where relay earns its keep.

Separate recording sends different media to different cards, commonly stills to one and video to the other, or a high quality master to one card and a light proxy file to the other. Hybrid shooters like it because the video card can be a high class card sized for footage, while the stills card stays smaller. Set the pattern deliberately and test it before a real shoot.

Counterfeit cards: how to spot one before it costs footage

The scam works because the card controller reports fake capacity to camera and computer. Everything looks normal, you record all day, and the early footage is silently destroyed as new data wraps over it. Creators usually discover the fraud at the edit. Fake cards also write far slower than their printed class, so they trigger mid-take stops too.

• Buy from authorised retailers or the maker own store. Unknown marketplace sellers at half the going rate are the main channel for fakes.
• Inspect the card and packaging. Genuine cards have crisp printing. Blurry logos or packaging with no serial information point the wrong way.
• Test every new card before trusting it. Free utilities write data across the full claimed capacity and read it back. Run one the day the card arrives, while a return is still easy, then record a long test clip in your highest bitrate mode.
• Watch for behaviour that makes no sense. A card that corrupts files or reports different capacity in different devices has told you what it is. Retire it, rather than demoting it to less important shoots.

Format in the camera, every time

Deleting files one by one, or formatting on a computer, leaves the card in a state your camera tolerates rather than prefers. The in camera format takes ten seconds, removes all doubt, and gives the card clean, unfragmented space, which helps sustained write speed.

Build the routine around the format. Copy the footage to your computer, verify the copy plays and matches the card file count, and back it up to a second location. Only then format in the camera. Formatting before the copy is verified is the one unforgivable card mistake, because it is instant and permanent. Use one card in one camera, and retire cards that error repeatedly even after an in camera format.

Treat cards as consumables with a working life, not as permanent storage. Rotate two or three cards so the writes spread across them, get footage off the card and backed up the same day, and replace any card that throws an error, slows down, or corrupts a file on a shoot that mattered, even once. A card costs a fraction of the camera it feeds. A lost day costs the whole shoot.

Recording stops mid-take: work through the causes

1. Card too slow for the mode. A V30 card in a 400 Mbps mode needs 50 MB/s and is guaranteed only 30 MB/s. It may survive short clips, then fail as the buffer empties into a card that cannot keep up. Fix it with a higher class card, or a lower bitrate mode. This is the most common cause.
2. Fragmentation and a nearly full card. A card deleted from, but not formatted, for months writes into scattered gaps, and many cards slow sharply past about 90 percent full. Copy off, format in camera, test again. This free fix solves more cases than people expect.
3. Fake capacity. If recordings vanish or corrupt past a certain amount of footage, suspect a counterfeit, especially a bargain card. The full write test above settles it. There is no fix, only replacement.
4. Not the card at all. Many cameras cap clip length, commonly at 30 minutes on older bodies, and most stop if they overheat. A stop at the same clip length every time is a limit, not a fault.

Change one thing at a time: same mode, different card; same card, lower bitrate; fresh format, same setup. Three short tests pin the cause in almost every case.

SD card questions, answered

Keep exploring

• Best Mirrorless Camera for Vlogging
• Vlogging Camera Settings Explained
• Best Vlogging Equipment for Beginners
• Best Drones for Vlogging
• How to Start a Travel Vlog