Rank #2 in Best 512GB MicroSD Card 2026: 10 Ranked, and Why Read Speed Misleads
SanDisk 512GB Extreme microSD Card + Adapter
Price and rating as shown on Amazon when we collected them. Both change.
The SanDisk 512GB Extreme microSD Card is the runner-up in this guide: a UHS-I microSDXC card sold with an adapter, priced at £109.00 and carrying a 4.7 rating across 101,077 ratings on Amazon. It sits at number two because the gap between what it promises and what it prints about itself is smaller than the cards around it — but it is not zero.
The marketing line is 190MB/s read, powered by SanDisk QuickFlow Technology, with up to 130MB/s write for shooting. The spec table on that same page has its own entry for 'Media Speed: 20 megabytes_per_second'. That is a third number, an order of magnitude below the headline, and it is not explained anywhere in the listing. Everything below — speeds, classes, sizes, ratings — comes from the Amazon listing itself. We have not tested this card.
How those 101,077 ratings break down
An average hides its own shape. This is the spread behind the 4.7 stars.
Specification
Exactly as published on the Amazon listing, field for field.
| Price | £109.00 |
|---|---|
| Rating | 4.7 out of 5, from 101,077 ratings |
| Advertised read speed | Up to 190MB/s (SanDisk QuickFlow Technology) |
| Advertised write speed | Up to 130MB/s |
| Media Speed (as listed) | 20 megabytes_per_second |
| Speed classes (as listed) | UHS Speed Class 3 (U3), Video Speed Class 30 (V30), Secure Digital Association Class 10 |
| App performance | Rated A2 |
| Model number | SDSQXAV-512G-GN6MA |
What buyers actually say
Quoted from customer reviews on Amazon
Verified purchase“Fast, good value card.”
Verified purchase“Good spec and works perfectly with Eufy cameras”
What it is up against
The rivals it was ranked against in Best 512GB MicroSD Card 2026: 10 Ranked, and Why Read Speed Misleads.
Questions people ask
How fast does the SanDisk 512GB Extreme read?
The listing claims card offload speeds of up to 190MB/s, powered by SanDisk QuickFlow Technology.
What write speed does it claim?
Up to 130MB/s write speeds, described as being for fast shooting.
Why does the spec table list 20 megabytes_per_second?
We cannot reconcile it. The bullets on the same SanDisk listing claim up to 190MB/s read and up to 130MB/s write, while the specification table lists 'Media Speed: 20 megabytes_per_second'. All three figures come from the one page, and no explanation for the third is given.
Will it record 4K video?
The listing says it is 4K UHD-ready with UHS Speed Class 3 (U3) and Video Speed Class 30 (V30).
Does it reach its top speed on its own?
SanDisk says to pair it with the SanDisk Professional PRO-READER SD and microSD to achieve maximum speeds. That reader is sold separately.
What is the A2 rating for?
The listing states the card is rated A2 for faster loading and in-app performance, which matters on smartphones as much as in cameras.
Comments
Reader comments are not checked against the manufacturer's claims above.
No comments yet
Be the first to add something we missed — a price change, a spec that turned out wrong, or how one of these held up.
Leave a comment
No account needed. Own one of these? Tell other readers how it actually performed.