Quick Verdict
The SanDisk 128GB Ultra is a microSDXC UHS-I card with up to 140 MB/s read speeds, Class 10, U1, and A1 ratings. For phones, tablets, Chromebooks, and everyday storage, it is a well-known, easy pick. The trade-off is that it is a U1 card, so it is not the best choice for sustained high-bitrate 4K video recording.
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Table of Contents
SanDisk 128GB Ultra Specifications
| Feature | Details |
| Model | SDSQUAB-128G-GN6MN |
| Capacity | 128 GB |
| Type | microSDXC, UHS-I |
| Read speed | Up to 140 MB/s |
| Speed classes | Class 10, U1, A1 |
| Video rating | Full HD (U1) |
| Listed features | Water proof |
| Compatible devices | Chromebooks, smartphones, and tablets, per the listing |
Pros and Cons
Pros
- Up to 140 MB/s read speed for fast file transfers
- A1 rating for smoother app performance on supported devices
- Class 10 and U1 for everyday photos and Full HD video
- Well-known brand with very wide compatibility
- Listed as water proof
Cons
- U1 rating is not ideal for sustained 4K video recording
- A1 is a lower app-performance class than A2
- Quoted speeds are maximums that depend on your device and reader
Performance and Real-World Use
What the ratings mean
The 140 MB/s figure is a maximum read speed under ideal conditions. The U1 rating guarantees a minimum sustained write speed of 10 MB/s, which is enough for Full HD video but not for high-bitrate 4K recording. If you shoot a lot of 4K, look for a card rated U3 or V30 instead.
Apps and everyday storage
The A1 rating is aimed at running apps from the card on supported Android devices. It also suits photos, music, offline videos, and general file storage on phones, tablets, and Chromebooks.
Who Should Buy the SanDisk 128GB Ultra?
A great fit if you…
- want a trusted-brand card for a phone, tablet, or Chromebook
- store photos, music, and Full HD video
- want faster read speeds for moving files around
Look elsewhere if you…
- record sustained 4K video and need a U3 or V30 card
- want the highest app-performance class (A2)
- need more than 128 GB of space
Alternatives to Consider
- Amazon Basics 128GB microSDXC: a U3 and A2 card with a lower maximum read speed. Read our review or the comparison.
- SanDisk Extreme: a faster SanDisk line with A2 and U3 ratings for demanding use.
- Larger capacity cards: step up to 256 GB if you fill 128 GB quickly.
Browse more gear in our gear review hub.
Frequently Asked Questions
How fast is the SanDisk 128GB Ultra?
It is listed at up to 140 MB/s read speed. Actual speeds depend on your device.
Is it good for 4K video?
It is rated U1, which suits Full HD video. For sustained 4K recording, choose a U3 or V30 card.
What devices does it work with?
The listing names Chromebooks, smartphones, and tablets, and it works with other devices that have a compatible microSD slot.
What does A1 mean?
A1 is an app-performance rating that helps with running apps from the card on supported devices.
Final Verdict on the SanDisk 128GB Ultra
For a reliable, widely compatible microSD card with fast read speeds, the SanDisk 128GB Ultra is a solid everyday choice. Pick a U3 or V30 card if you record a lot of 4K video.