How Much Storage Should You Quote for 30 Days of CCTV Recording?

Quick Answer: How Much CCTV Storage Is Needed for 30 Days?

There is no single hard drive size that works for every 30-day CCTV project.

The storage requirement mainly depends on:

• Number of cameras
• Average bitrate per camera
• Recording time per day
• Number of recording days
• Continuous or event-based recording
• Resolution and frame rate
• Video compression settings
• Amount of movement in the scene

For 24/7 continuous recording, a useful planning formula is:

Storage (TB) ≈ Number of Cameras × Bitrate (Mbps) × 0.324 × Recording Days ÷ 30

For a 30-day project, this becomes:

Storage (TB) ≈ Number of Cameras × Bitrate (Mbps) × 0.324

For example:

8 cameras × 4 Mbps × 0.324 ≈ 10.37 TB

So an eight-camera system averaging 4 Mbps per camera would require roughly 10.4 TB of theoretical video storage for 30 days of continuous recording, before allowing additional capacity for real-world operating conditions.

This is why CCTV installers should calculate storage from the actual project requirements instead of automatically quoting a 2TB, 4TB or 8TB hard drive.

Why CCTV Storage Is Often Misquoted

A common project mistake is selecting storage based only on the number of cameras.

For example:

“Eight cameras? A 4TB HDD should be enough.”

That may work for one project and fail badly for another.

Eight cameras recording at a relatively low bitrate are very different from eight high-resolution cameras recording complex scenes at higher bitrates.

If the storage estimate is too low, the customer may expect 30 days of recording but discover that older footage is overwritten after only 10 or 15 days.

For installers and system integrators, that can create:

• Customer complaints
• Emergency HDD upgrades
• Additional site visits
• Labor costs
• Project delays
• Reduced profit
• Disputes over the original quotation

Storage should therefore be treated as part of the project design, not simply as an NVR accessory.

The Basic CCTV Storage Calculation

For continuous recording, the underlying calculation is straightforward.

Step 1: Start With the Camera Bitrate

Assume one camera averages:

4 Mbps

Convert megabits to megabytes:

4 ÷ 8 = 0.5 MB/s

Step 2: Calculate One Day of Recording

There are 86,400 seconds in one day:

0.5 MB/s × 86,400 = 43,200 MB/day

That is approximately:

43.2 GB per day

Step 3: Calculate 30 Days

43.2 GB × 30 = 1,296 GB

Approximately:

1.30 TB per camera

Step 4: Multiply by Camera Quantity

For eight cameras:

1.30 TB × 8 ≈ 10.4 TB

Therefore:

8 cameras averaging 4 Mbps and recording continuously for 30 days require approximately 10.4 TB of theoretical storage.

30-Day CCTV Storage Reference Table

The following examples show how dramatically bitrate can change the storage requirement.

Average Bitrate	1 Camera / 30 Days	4 Cameras	8 Cameras	16 Cameras
2 Mbps	0.65 TB	2.59 TB	5.18 TB	10.37 TB
4 Mbps	1.30 TB	5.18 TB	10.37 TB	20.74 TB
6 Mbps	1.94 TB	7.78 TB	15.55 TB	31.10 TB
8 Mbps	2.59 TB	10.37 TB	20.74 TB	41.47 TB

Important: These are theoretical estimates for 24/7 recording. Actual storage consumption can vary according to encoding settings, scene complexity, frame rate, recording mode and other NVR/camera configurations.

That is why bitrate is usually more useful for storage planning than simply saying “this is a 5MP camera” or “this is an 8MP camera.”

Resolution Alone Does Not Tell You the Storage Requirement

One of the easiest mistakes to make during a CCTV quotation is calculating storage only from resolution.

An 8MP camera generally has the potential to produce more video data than a lower-resolution camera, but resolution is not the only factor determining storage.

Two cameras with the same resolution can consume very different amounts of storage.

You also need to consider:

Bitrate

Bitrate directly affects how much data is written to the HDD.

A camera averaging 8 Mbps will theoretically consume around twice as much storage as a camera averaging 4 Mbps under the same recording duration.

Frame Rate

A project recording at a higher frame rate may require more data than one using a lower frame rate, depending on the encoding configuration.

Scene Complexity

A quiet indoor corridor is different from:

• A busy parking lot
• A highway entrance
• Moving trees
• Heavy rain
• Crowded retail areas
• Warehouses with frequent forklift movement

More visual changes can increase the amount of video data required, particularly when variable bitrate is being used.

Compression

Modern IP camera systems often use H.264 or H.265 compression.

The actual storage saving depends on the camera, NVR, scene and encoding configuration, so installers should avoid promising a fixed percentage of storage reduction without testing the actual equipment.

Continuous Recording vs. Event Recording

Another important question is:

Does the customer really need 24/7 continuous recording?

This decision can significantly affect storage requirements.

Continuous Recording

Continuous recording is often preferred when:

• Complete evidence history is required
• Operators need to review events before motion detection begins
• The project has compliance or operational requirements
• Missing footage is unacceptable

The disadvantage is higher storage consumption.

Motion or Event Recording

Event-based recording may reduce storage requirements when cameras are installed in locations with long periods of inactivity.

However, actual storage usage becomes harder to predict because it depends on how frequently events are triggered.

For example, motion recording at a quiet equipment room may save substantial storage.

The same configuration at a busy retail entrance may record for most of the day anyway.

Therefore, for B2B project quotations, do not simply assume:

“Motion recording means we need 50% less storage.”

The correct question is:

How active is the scene during a normal day?

Should You Quote Exactly the Calculated HDD Capacity?

Usually, it is safer not to size the system exactly at the theoretical minimum.

Suppose your calculation gives:

10.4 TB

That does not automatically mean you should promise exactly 30 days of retention from a nominal capacity that barely exceeds that number.

A practical quotation should consider additional headroom because actual recording behavior may differ from the original assumptions.

Reasons include:

• Bitrate fluctuations
• Different camera configurations
• Higher activity than expected
• Recording schedule changes
• Future camera adjustments
• Storage management overhead
• Customer adding cameras later

For important commercial projects, a storage calculation should therefore be presented as an estimate based on confirmed recording conditions, not as an unconditional guarantee.

Example 1: 8-Camera Warehouse Project

Consider a warehouse project with:

• 8 IP cameras
• 24/7 recording
• 30-day retention
• Approximate average bitrate: 4 Mbps per camera

Calculation:

8 × 4 × 0.324 ≈ 10.37 TB

The theoretical requirement is approximately:

10.4 TB

Before quoting the final HDD configuration, the installer should still confirm:

• Actual camera encoding settings
• Required frame rate
• H.264 or H.265
• Continuous or event recording
• Whether all cameras use the same bitrate
• Whether the customer may add cameras later
• Maximum HDD capacity supported by the NVR
• Number of SATA bays available

That last point is important.

A storage requirement can be mathematically correct but still be impossible to configure on the selected NVR.

Example 2: 16 Cameras Do Not Always Mean Twice the Storage

Imagine another project with 16 cameras.

It is tempting to assume:

Twice the number of cameras = twice the previous storage requirement.

That is only true if the cameras use similar recording settings.

A real commercial installation might have:

• 4 entrance cameras requiring higher detail
• 6 warehouse cameras using moderate bitrate
• 4 corridor cameras requiring less detail
• 2 overview cameras with different recording schedules

Instead of forcing every camera into one identical configuration, professional system design can calculate storage by camera group.

For example:

Total Storage = Storage Group A + Group B + Group C + Group D

This method can create a more realistic quotation without unnecessarily increasing HDD capacity.

7 Questions Installers Should Ask Before Quoting CCTV Storage

Before deciding the NVR hard drive capacity, confirm these seven items.

1. How many cameras will record?

Also ask whether expansion is expected.

2. How many days must footage be retained?

7 days, 15 days, 30 days, 60 days and 90 days create very different requirements.

3. Is recording continuous or event-based?

Do not estimate motion-recording savings without understanding scene activity.

4. What bitrate will each camera use?

This is one of the most important inputs in the storage calculation.

5. What resolution and frame rate are required?

Higher specifications may increase storage and NVR processing requirements.

6. What compression format will be used?

Confirm the actual camera and NVR configuration rather than assuming a theoretical compression saving.

7. Can the selected NVR physically support the required HDD capacity?

Check:

• Number of SATA interfaces
• Maximum capacity per HDD
• Total supported storage
• Camera channel capacity
• Recording bandwidth

A project is not properly designed until both storage requirement and NVR capability have been checked.

Storage Is Also a Cost-Control Decision

For installers, system integrators and project buyers, storage is not just a technical specification.

It directly affects the project quotation.

Oversizing storage can increase:

• Hardware cost
• Quotation price
• Project competitiveness

Undersizing storage can increase:

• Return visits
• Upgrade costs
• Customer complaints
• Warranty disputes
• Labor
• Project risk

The goal is therefore not:

“Use the biggest HDD possible.”

The goal is:

Provide enough storage to meet the actual retention requirement with an appropriate operating margin.

That protects both the customer and the installer’s project profit.

A Better Way to Quote CCTV Storage

Instead of writing only:

16CH NVR + 8TB HDD

a professional quotation can state the design assumption.

For example:

Storage configuration is calculated based on the confirmed camera quantity, average recording bitrate, recording schedule and required retention period. Final recording days may vary with actual encoding and scene activity.

This helps the customer understand what the quotation is based on and reduces misunderstandings later.

For larger projects, installers can also separate the quotation into:

Camera Configuration → Recording Settings → Retention Requirement → Calculated Storage → NVR/HDD Configuration

This makes different supplier quotations much easier to compare.

CCTV Storage Calculation Checklist

Before finalizing your next CCTV quotation, confirm:

• Camera quantity
• Camera resolution
• Average bitrate
• Frame rate
• H.264 / H.265
• Continuous or event recording
• Hours recorded per day
• Required retention days
• Scene activity
• NVR recording bandwidth
• Number of SATA bays
• Maximum HDD capacity
• Future camera expansion

If even one of these requirements changes, the final storage recommendation may also change.

Frequently Asked Questions

How much storage does one CCTV camera need for 30 days?

It depends primarily on bitrate and recording duration. For 24/7 recording, a camera averaging 4 Mbps requires approximately 1.3 TB of theoretical storage for 30 days.

How much storage do 8 cameras need for 30 days?

If all eight cameras average 4 Mbps and record continuously:

8 × 4 × 0.324 ≈ 10.4 TB

Actual requirements may vary according to camera settings and recording conditions.

Is 4TB enough for 8 security cameras?

It may be sufficient for some configurations, but camera count alone cannot answer this question. Bitrate, recording mode, resolution, frame rate and required retention period must also be considered.

Does H.265 reduce CCTV storage?

H.265 can improve compression efficiency compared with older encoding methods, but the actual storage requirement still depends on the implementation, bitrate settings, scene activity and camera/NVR configuration.

Does an 8MP camera require more storage than a 5MP camera?

It can, but resolution alone is not enough to calculate storage. The configured bitrate is one of the most important factors for determining actual storage consumption.

Is motion recording better than continuous recording?

It depends on the project. Motion or event recording can reduce storage in low-activity locations, while continuous recording provides a complete timeline. The decision should be based on the customer's evidence and retention requirements.

Should installers leave extra HDD capacity?

For commercial projects, it is sensible to avoid designing exactly to the theoretical minimum. Bitrate and recording conditions can change, so a reasonable operating margin can reduce the risk of missing the required retention period.

What information should I provide before requesting an NVR storage quotation?

Provide at least:

• Number of cameras
• Camera resolution
• Expected bitrate if known
• Recording hours
• Continuous or event recording
• Required recording days
• Future expansion requirements

With these details, a supplier or system integrator can recommend a more appropriate NVR and HDD configuration.

Final Takeaway

The right question is not:

“How many terabytes do I need for eight cameras?”

The better question is:

“How much data will these cameras generate under the customer's actual recording requirements?”

For a 30-day CCTV project, start with:

Camera Quantity × Average Bitrate × Recording Time × Retention Days

Then check whether the selected NVR has enough recording bandwidth, SATA capacity and future expansion room.

For CCTV installers, distributors and system integrators, getting this calculation right before quotation helps prevent both overconfiguration and insufficient storage—protecting project cost, customer expectations and long-term profitability.