What size SD card does a 4K front and rear dash cam need?
A 256GB card keeps a full 8-hour driving day from a 4K front and rear dash cam at a typical 42 Mbps; 64GB covers a 2-hour commute. Buy a high-endurance card and check your camera's maximum supported size.
SANDISK 256GB High Endurance microSD Card + Adapter
256GB / high endurance
The 256GB size that holds a full driving day at this setting, in a high-endurance grade built for loop recording.
How big a card for how many hours?
A 4K front and rear camera writes about 18.9GB per hour at a typical 42 Mbps. Each extra 1080p channel adds about 10 Mbps, which is why the rear camera costs you roughly 24 percent of the loop.
| Hours to keep | Space needed | Card to buy |
|---|---|---|
| 1 h | 20 GB | 32GB |
| 2 h | 41 GB | 64GB |
| 4 h | 81 GB | 128GB |
| 8 h | 163 GB | 256GB |
| 12 h | 244 GB | 256GB |
| 24 h | 488 GB | 512GB |
How long does each card size last at this setting?
| Card | Loop length |
|---|---|
| 16GB | 47 min |
| 32GB | 1 h 34 min |
| 64GB | 3 h 9 min |
| 128GB | 6 h 18 min |
| 256GB | 12 h 36 min |
| 512GB | 25 h 12 min |
Cards and 4K front and rear cameras
Check the camera's maximum supported card size before buying.
SANDISK 128GB High Endurance Video microSDXC Card with Adapter for dash cam and home...128GB / high endurance$36.99Check price on Amazon
Integral 128GB High Endurance microSD Card for CCTV, Dash Cam & Security Cameras, 4K...128GB / high endurance$38.95Check price on Amazon
VIOFO 64GB Industrial Grade High Endurance microSDXC Card for Dash Cam64GB / high endurance$39.99Check price on Amazon
Dash Cam Front and Rear 4K+1080P, 5GHz WiFi, App Control, with 64GB Card4K / 2 channel / Wi-Fi$45.99Check price on Amazon
Frequently asked questions
Is 128GB enough for a 4K front and rear dash cam?
128GB holds about 6 h 18 min at this setting. That covers daily commuting, but a long road-trip day or heavy parking-mode use can overwrite footage before you check it, so 256GB is the safer choice if your camera supports it.
Do I need a high-endurance SD card?
Yes. A dash cam rewrites its whole card every few hours, and ordinary cards are not rated for that. High-endurance cards are built for continuous video and handle windshield heat better. A worn-out card often keeps recording but writes corrupt files, so format it in the camera every few weeks and replace it at the first recording error.
What speed class does a dash cam card need?
Even a three-channel 4K camera writes only a few megabytes per second, so a U3 or V30 card is enough. This setup writes about 5.3 MB per second. Endurance, not speed, is what decides how long a card lasts.