Surveillance Guide

How Much Storage Do Security Cameras Need? Storage Calculator, Hard Drive Sizing, and GB per Camera

A single 1080p camera recording around the clock with H.265 uses roughly 20 GB a day, so eight of them keep 30 days of footage on about a 6 TB drive. Push to 4K and that same eight-camera system needs closer to 20 TB. Your storage total comes down to three numbers: how many cameras, at what resolution, kept for how many days. Here is the math, the drive sizing, and the levers that cut the total.

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The Short Answer

How Much Storage a Security Camera System Needs

Storage is a multiplication problem. Take how much data one camera writes per day, multiply by the number of cameras, then multiply by how many days you keep the footage. For continuous recording with the H.265 codec, a typical 1080p camera writes about 20 GB a day, a 4MP camera about 40 GB, and a 4K camera roughly 85 GB. Those three numbers, times your camera count, times your retention days, give you the terabytes you need before any safety margin.

For a quick benchmark: an eight-camera 1080p system kept for 30 days needs about 5 to 6 TB, the same eight cameras at 4K need close to 20 TB, and a sixteen-camera 4MP system at 30 days lands near 20 TB. Double the retention and you double the drive. Switch every camera from H.264 to H.265 and you roughly halve it. There is no single answer because resolution and retention swing the total by an order of magnitude.

The number most buyers underestimate is retention. A business often thinks it needs a week of footage, then a slip-and-fall claim or a payroll dispute surfaces six weeks later and the footage is already gone. Decide the retention window first, because it is the multiplier that sets the whole storage budget. The table and calculator below turn your specific setup into a drive size.

Per Camera, Per Day (H.265, 24/7)

1080p (2MP)~20 GB

4MP~40 GB

4K (8MP)~85 GB

Motion-only50-80% less

H.264 instead~2x more

Continuous recording at 30 fps. Actual figures vary with scene motion, bitrate mode, and quality settings.

Storage by System Size

Security Camera Storage Calculator: TB by Cameras and Retention

These are total hard drive sizes for continuous H.265 recording at 30 frames per second, rounded up to the next common drive size with a margin for overhead. Halve the figure for H.264-to-H.265 savings the other way, and cut it 50 to 80 percent more if you record on motion only.

System	7 days	30 days	90 days
4 cameras, 1080p	~1 TB	~3 TB	~8 TB
8 cameras, 1080p	~2 TB	~6 TB	~16 TB
8 cameras, 4MP	~3 TB	~10 TB	~30 TB
8 cameras, 4K	~5 TB	~20 TB	~60 TB
16 cameras, 1080p	~3 TB	~10 TB	~30 TB
16 cameras, 4MP	~5 TB	~20 TB	~60 TB
16 cameras, 4K	~10 TB	~40 TB	~120 TB

Figures assume continuous recording. Recording on motion only, which most business sites use, commonly drops these totals by half or more. A camera watching a busy entrance fills more than one watching a quiet stockroom.

What Moves the Number

What Affects How Much Storage a Camera Uses

Five settings decide your storage total. Two of them, retention and codec, dwarf the rest, so set those first.

Retention Days

How long you keep footage is the biggest single lever, and it scales the total directly. Thirty days needs four times the storage of seven. Set this from your actual need, false-claim windows, insurance and license rules, and how late incidents surface, before you size a single drive.

Codec (H.264 vs H.265)

The compression codec is the second biggest lever. H.265 stores the same picture in roughly half the data of H.264, so turning it on can nearly double your retention on the same drive. Smart or "+" modes squeeze static scenes further. Both the camera and the recorder must support H.265.

Resolution

More megapixels means more data. Jumping from 1080p to 4K roughly quadruples the pixel count and lands around four times the storage at the same settings. Use 4K where you need to read a face or plate, and 1080p or 4MP where general coverage is enough, rather than maxing every camera.

Frame Rate

Frames per second scale storage almost linearly. Dropping from 30 fps to 15 fps roughly halves the file size and is still smooth for most surveillance. Many sites run lobbies and parking lots at lower frame rates and reserve 30 fps for points of sale and cash handling.

Recording Mode

Continuous recording writes 24 hours a day. Motion-only or scheduled recording writes only when something happens, which on a typical commercial site cuts storage 50 to 80 percent. The trade-off is that anything the motion detector misses is not saved, so high-value areas often stay on continuous.

Scene Activity

A busy loading dock or a sidewalk full of traffic produces more change for the codec to encode than a quiet hallway, so it uses more data even at identical settings. Build in a margin for your busiest cameras rather than sizing on an average, or one camera can fill more than its share.

Storage and Bandwidth Are the Same Number

The bitrate that flows over your network is the same data that fills your drives, so the bandwidth you plan and the storage you buy are two views of one figure. A simple conversion ties them together: multiply a camera bitrate in Mbps by about 10.8 to get gigabytes per day. A 1080p camera at 2 Mbps in H.265 works out to roughly 22 GB a day, which is where the per-camera numbers above come from. Our guide on security camera bandwidth covers the network side of the same math, and H.264 vs H.265 shows exactly how the codec halves both.

Pick the Drive

What Size Hard Drive Do You Need for Security Cameras?

Sizing the drive is the storage total plus a margin, on the right kind of disk. A surveillance system writes data continuously, which is a workload a desktop drive is not built for.

Use Surveillance-Rated Drives

Drives built for surveillance, such as WD Purple or Seagate SkyHawk, are rated for the constant 24/7 write workload a camera system creates and for many drives streaming at once. A standard desktop drive often fails early under that duty cycle. The price difference is small next to losing footage when a disk dies, so this is not the place to save money.

Add 10 to 20 Percent Margin

Your calculated terabytes are the floor, not the buy. Add 10 to 20 percent for filesystem overhead, the fact that a labeled 4 TB drive formats to a bit less, and the camera or two you will add later. Sizing to the exact number means a full disk that starts overwriting footage sooner than your retention window promises.

Plan for Redundancy on Bigger Sites

A single drive is one failure away from losing everything. Recorders with multiple bays can run RAID so one disk can fail without losing footage, and larger sites mirror to a second location or the cloud. Decide how much footage you can afford to lose, then choose single drive, RAID, or cloud backup to match.

Local Drives, Cloud, or Both

On-site storage on an NVR or DVR has no monthly fee and keeps footage on your network, but the drive sits at the same site as the cameras, so a fire, flood, or stolen recorder can take the evidence with it. Cloud storage moves footage off site automatically, survives a break-in or disaster, and lets a manager review any location from a phone, in exchange for a recurring cost and the upload bandwidth to send video out. Many businesses run both: keep full continuous footage locally for the bulk of retention, and push flagged events or a shorter window to the cloud as an off-site copy.

Surveillant connects to the IP cameras and recorders you already run, then stores footage in cloud video surveillance with the retention you choose, so you set the window without swapping drives. How long you should keep footage in the first place, by industry and by rule, is covered in our guide on how long to keep security camera footage, and the recorder side of the decision is in our NVR vs DVR comparison.

Do the Math

How to Calculate Security Camera Storage

Four steps turn a camera list into a drive size. No special tool required.

01

Find GB per Camera per Day

Use the per-camera figures above, or take each camera bitrate in Mbps from its spec sheet and multiply by 10.8 for gigabytes per day at continuous recording. A 1080p H.265 camera at 2 Mbps is about 22 GB a day.

02

Multiply by Camera Count

Add up the daily gigabytes for every camera. Mixed systems are just the sum: six 1080p cameras at 20 GB plus two 4K cameras at 85 GB is 290 GB a day. This is your whole-system daily storage.

03

Multiply by Retention Days

Multiply daily storage by how many days you keep footage. At 290 GB a day, 30 days is 8,700 GB, about 8.7 TB. This step is where your retention policy turns directly into terabytes.

04

Add Margin and Pick a Drive

Add 10 to 20 percent for overhead and growth, then round up to the next surveillance-drive size. The 8.7 TB example becomes a 10 to 12 TB drive. Apply any motion-only saving before you buy if you record on motion.

FAQ

Common Questions About Security Camera Storage

How much storage do security cameras need?

It depends on camera count, resolution, and retention days. As a benchmark for continuous H.265 recording, a 1080p camera uses about 20 GB a day, so an eight-camera 1080p system keeps 30 days on roughly 6 TB. The same eight cameras at 4K need close to 20 TB. Multiply daily gigabytes per camera by the number of cameras and your retention days to get the total.

How many GB does a security camera use per day?

A typical 1080p camera recording continuously with H.265 uses about 20 GB a day, a 4MP camera about 40 GB, and a 4K camera roughly 85 GB. H.264 roughly doubles those figures. Recording on motion only, instead of around the clock, commonly cuts the daily total by 50 to 80 percent depending on how busy the scene is.

What size hard drive do I need for security cameras?

Calculate your total storage, then add 10 to 20 percent and round up to the next surveillance-drive size. For example, an eight-camera 1080p system at 30 days needs about 6 TB, so an 8 TB drive gives headroom. A four-camera 1080p system at 30 days fits on about 3 to 4 TB. Always use a surveillance-rated drive, not a desktop one.

Is a 1TB or 2TB hard drive enough for security cameras?

A 1 TB drive holds only a few days for most multi-camera systems and is really suited to one or two cameras or a short retention window. A 2 TB drive covers about 30 days for four 1080p cameras recording on motion, but fills in roughly a week at continuous 4K. For an eight-camera system at 30 days, plan on 6 TB or more.

Do security cameras need a special hard drive?

Yes, use a surveillance-rated drive such as WD Purple or Seagate SkyHawk. These are built for the 24/7 continuous-write workload of a camera system and for many video streams writing at once. Standard desktop drives are designed for occasional use and tend to fail early under constant recording, which risks losing the footage you installed the cameras to capture.

How can I reduce security camera storage use?

The four biggest levers are codec, recording mode, resolution, and frame rate. Switch cameras to H.265 to roughly halve storage, record on motion instead of continuously to cut 50 to 80 percent, lower the frame rate from 30 to 15 fps, and reserve 4K for cameras that need to read faces or plates while running general coverage at 1080p or 4MP.

Is cloud or local storage better for security cameras?

Local storage on an NVR has no monthly fee and keeps footage on site, but it can be lost to fire, flood, or a stolen recorder. Cloud storage survives those events, moves footage off site automatically, and lets you review any location remotely, in exchange for a recurring cost and upload bandwidth. Many businesses keep full footage locally and push flagged events to the cloud as a backup.

Explore More

Stop Sizing Drives, Start Choosing Retention

Surveillant connects to the IP cameras and recorders you already run, stores footage with the retention you choose, and makes every clip searchable with AI. Start a free 14-day trial and pick the window instead of the disk.