What should you buy an SD card for the dashcam?

[Becky_70mai]

A lot of people buy a dash cam and then immediately wonder:“What SD card should I get? Just pick any of them?”
Prioritise “write speed” and “durability”. Don't just focus on the brand or capacity.

What actually matters​

You’ll usually see labels like:

• U1 / U3 (speed class)
• A1 / A2 (performance class)

✔ For dash cams, the most important one is: U3 (sustained write speed)
Because a dash cam is constantly recording and overwriting footage in a loop.
Higher resolution = higher bitrate = more stress on the card.

 

[Becky_70mai]

What to choose based on resolution？​

2.5K and below (e.g. 70mai M310 Plus/ A510)​

• Recommended: U3 is enough
• Why: Lower data load means you mainly just need stable saving. Avoid issues like footage not saving or recording failures.

4K resolution (e.g. 70mai A810S / T800 / X800)​

• Recommended:
  • U3 + High Endurance (look for labels like “High Endurance Pro”)
  • Ideally A1 rated

 

[Becky_70mai]

4K footage has a much higher bitrate, and continuous recording puts heavy wear on the card. This is also one of the common reasons for dropped frames, corrupted footage and recording glitches.
👉 Don’t cheap out on the SD card. It directly affects whether your footage is actually usable.