RoadReadyCalc
SD card size

What size SD card does a 4K front, rear and cabin dash cam need?

Quick answer

A 256GB card keeps a full 8-hour driving day from a 4K front, rear and cabin dash cam at a typical 52 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

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, rear and cabin camera writes about 23.4GB per hour at a typical 52 Mbps. Each extra 1080p channel adds about 10 Mbps, which is why the rear camera costs you roughly 19 percent of the loop.

Hours to keepSpace neededCard to buy
1 h25 GB32GB
2 h50 GB64GB
4 h101 GB128GB
8 h201 GB256GB
12 h302 GB512GB
24 h604 GBover 512GB

How long does each card size last at this setting?

CardLoop length
16GB38 min
32GB1 h 16 min
64GB2 h 33 min
128GB5 h 5 min
256GB10 h 10 min
512GB20 h 21 min

Cards and 4K front, rear and cabin cameras

Check the camera's maximum supported card size before buying.

Before you rely on this: Windshield-mount rules and audio-recording consent laws vary by state, so check your local law. Researched from published specifications and verified owner reviews, not hands-on testing. General information, not professional advice; check your vehicle manual and your local law.

Frequently asked questions

Is 128GB enough for a 4K front, rear and cabin dash cam?

128GB holds about 5 h 5 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 6.5 MB per second. Endurance, not speed, is what decides how long a card lasts.

Updated 2026-09-24