Memory Card Speed Ratings Questions

My "best" camera is a Nikon Z50 (might become a Z5 full-frame later, but that's another story). My other camera is a Sony RX100 III, along with two Nikon D3200s I rarely use (one is for the wife). I am almost exclusively photos, any videos I shoot is done with my phone or with the Sony RX100 III.

My two best memory cards, both Sony SD, are a 128G with "10-3" as the classification (whatever that means) and 94 Mb/s. The other is a 64G "10-1" with a rating of 40Mb/s. (I also have a few 32G that say "10-3" and rated at 90Mb/s, but they're 32G vs 64G.)

As I'm about to go on a 5-day cross-country vacation next May (funeral, my mother's service, and may reunite with some family and see some things etc), I wanted to make sure I'm up to snuff with what I have memory-card wise. Photos, I've never had a problem with any of these cards with any "bursts" shots, but especially when I shoot video with the RX100 III I wanted to make sure the speed ratings were up to snuff. (I don't recall, but I THINK the video files are set to 1080p/60fps). Basically, are these cards fine or would I be advised to get newer ones with faster ratings?

As for capacity, I've always found even 32G to be enough, so 64-128G should be an absolute boat-load of plenty, and besides I'm likely to take a laptop PC with an SSD external hard drive (1T I believe) for "offloading" any photos on a daily basis.

If you share links to pages that give a run-down on what the speed ratings mean and what's good enough for what scenario etc, that's fine.

Thanks for the help. It looks like the 128G is a UHS-3 and the 64G is a UHS-1. It seems to also say that a classic 10 (10-1, UHS-1) is capable of full HD (1080p?), which I think is what the RX100 III is capable of doing.

So, it sounds like I'm good? (On the other hand looking at DPreview, while it's still here, it says the RX100 III does 1080p/60fps at 50 Mb/S, and the UHS-1 (10-1) 64G card says 40 Mb/s, so it sounds like I should use the faster 128G with it for that reason?) It gets confusing too because the 64G UHS-1 says 40Mb/s but I also have a SanDisk 32G which is also UHS-1 but it says it can do 80 Mb/s. It gets sort of confusing after awhile.

With the purchase of my Fujifilm X-T5 which has a small buffer memory.
I decided to get myself a memory card that assumes. So as not to be frustrated during continuous shooting.
A 64GB SanDisk Extreme PRO 300MB/s V90, gives me peace of mind 😇
See here

The "Circle 10" symbol means "Speed Class 10". You do need to worry about this. This is usually what you see in the SD card.

You need to care about "U1" or "U3". U1 means "UHS-I Speed Class 1", while "U3" means "UHS-I Speed Class 3". U3 is faster than U1. We usually look for U3.

For U3 cards, there is usually one more label "V30", which means "Video Speed Class 30MB/sec", which should be good enough for 1080P video.

In summary, you should look for and use "Speed Class 10" (Circle 10), "U3" and "V30" card as minimum. You should also use reputable brands, such as Sandisk, Lexar, Sony, Samsung, etc.

Your Z50 and RX100 III do not support UHS-II, and these cards are sold at a premium, so do not worry about that for now.

Yes I meant UHS Class 3.

Where I'm also confused, I have a UHS Class 3 card that says it has 100 Mb/s, whereas my Sony 128G is around 90. So apparently Mb/s varies even within the same class? Is this right, and if so, which do I go by?

Please note that the "Speed Class" rating specifies the minimum sustained sequential transfer speed achievable by the SD Card. Surely the cards can go faster than that.

The UHS-1 Interface has a maximum theoretical speed of 104MB/sec. Practically the cards should be 90~ something MB/sec. So your Sony 128G should be fine too.

If you would like to confirm which card is faster, you may have a look at CrystalDiskMark, a simple and easy-to-use benchmark tool to check the real speed of your card.

Thanks for your help, and other's help as well.

I was about to buy another 128G much like the Sony then I found a second such Sony 128G card in my Z50 camera (I bought 2 at the time but the 2nd one was missing until today). So I have two such 128G Class 10-3 (UTS Class 3) 90 Mb/s Sony cards, one each for the Z50 and Sony RX100 III. I should be fine now, but thanks for the 101 class on card speeds.