What Size SD Card Do You Need For A Security Camera?

The right SD card (ever wonder what the SD stands for?) size for your security camera depends on how your system records, the resolution it uses, and how often you review or overwrite footage. If your camera records in 1080p and only when motion is detected, 32GB or 64GB is usually enough. For 24/7 recording or higher resolutions like 2K or 4K, aim for 128GB, 256GB, or more.

A 1080p camera doing continuous recording uses around 4–8GB per hour, while a 4K camera burns through 8–16GB per hour. So, if you need more than a day's worth of backup on a 4K camera, you're looking at 256GB minimum. For motion-activated cameras in low-traffic zones, you can stretch that to more hours on the same card size.

Camera compatibility also matters. Many older or cheaper models max out at 64 GB. Most modern cameras accept up to 128GB or larger, but anything above that might go unsupported. Always check the camera's product page or manual first. One final note: don't go too small. If your card fills up and your camera can't overwrite data, it will stop recording. That's how people end up missing important footage. If you want set-it-and-forget-it reliability, go larger than you think you need.

Not all cameras record the same way or in the same environment. That makes a one-size-fits-all SD card approach a mistake. For indoor cameras with motion-triggered recording, 32GB might cover a week or more. These cameras usually face quiet areas like hallways or living rooms, and unless they're capturing a lot of motion, they don't need much space.

For outdoor cameras monitoring entryways, driveways, or street-facing views, bump up to at least 128 GB. Footage quality is often higher, and motion detection gets triggered more often by people, cars, pets, or even weather changes. If your camera is shooting in 2K or 4K, 256GB gives you more breathing room without risking early overwrites.

Multi-camera systems or setups in high-traffic areas are in a different league. Here, 256GB to 512GB is the practical range, especially for continuous recording. And for business use or properties where footage must be saved for legal reasons, local storage should be paired with a backup, either a larger drive (like SSD in a base station) or cloud redundancy.

Capacity is only half the equation. Write speed, endurance, and card authenticity matter just as much. Security cameras are constantly writing video files. Slow cards cause skipped frames or slow performance. You need at least a Class 10 card, and ideally one with a UHS-I rating. Don't cheap out. Use high-endurance cards built for surveillance. Brands like SanDisk High Endurance, SanDisk MAX Endurance, Samsung PRO Endurance, and Kingston Endurance are purpose-built for constant writing and rewrites. These cards last longer and won't corrupt easily, and are definitely worth the extra cost. 

Fake SD cards are another issue. Counterfeit models often fake their capacity. You might buy what you think is a 256GB card, but it's actually a reprogrammed 32GB card that corrupts all files after that mark. To avoid this, buy from reputable sellers only. Tools like H2testw (Windows) or F3 (Mac/Linux) can test real capacity if you're unsure.

Lastly, remember to format your card in the camera or its app before first use. And if you're using SD cards for more than a few years of continuous recording, replace them. Cards wear out, and when they fail, you lose everything. You can also find some unexpected uses for old SD cards.