How Much Storage for Security Cameras? 2026 Calculator

How much storage for security cameras do you actually need? A single 4K camera at 24/7 recording burns through 1 TB in about 7 days. An 8-camera 4K system at continuous record needs a 20 TB drive to hold 30 days of footage. Cut those numbers in half with motion-only recording, and in half again with H.265 compression. This 2026 guide breaks down the math, shows the real TB-per-day numbers by resolution and codec, explains motion-only and smart detection, and points to the best NVR drive models for 24/7 writes.

Security Camera Storage: Quick Storage Needs Table

CamerasResolutionCodecRecord mode30-day storage
41080pH.26524/71 TB
41080pH.265Motion only400 GB
44KH.26524/74 TB
44KH.265Motion only1.5 TB
81080pH.26524/72 TB
84KH.26524/78 TB
84KH.26424/716 TB
164KH.26524/716 TB
164KH.265Motion only6 TB

All values assume a standard 15 fps record rate and medium motion activity. Heavy motion scenes (busy street, parking lot) add about 50 percent. Static scenes (back yard, indoor storage room) cut numbers in half.

Storage Math by Bitrate

The exact formula: storage per day (GB) = bitrate (Mbps) x 10.8. Here’s the breakdown per camera:

  • 1080p H.264: 4 to 6 Mbps = 43 to 65 GB/day = 1.3 to 2 TB/month.
  • 1080p H.265: 2 to 3 Mbps = 22 to 32 GB/day = 660 GB to 1 TB/month.
  • 4K H.264: 12 to 16 Mbps = 130 to 170 GB/day = 4 to 5 TB/month.
  • 4K H.265: 6 to 8 Mbps = 65 to 86 GB/day = 2 to 2.6 TB/month.
  • 4K H.265+ (smart encoding): 3 to 5 Mbps = 32 to 54 GB/day = 1 to 1.6 TB/month.

H.265 roughly doubles the retention you get from the same drive compared to H.264. Smart encoding variants (H.265+, Smart Codec, SVC) detect static scenes and drop bitrate, saving another 30 to 50 percent.

Recording Modes Compared

  • 24/7 continuous: every second is recorded. Most storage, easiest to review (seek any moment). Default on most NVRs.
  • Motion only: records only when motion is detected. Typical savings: 60 to 70 percent for a quiet scene. Easy to miss context if motion zone is too tight.
  • Smart detection: records only for person, vehicle, or package events (AI-filtered). Savings: 80 to 90 percent. Requires an NVR with onboard AI (Reolink, Hikvision AcuSense, Dahua WizSense).
  • Scheduled: continuous during high-interest hours (e.g. 6 PM to 6 AM), motion-only during the day. Mix of the two.
  • Pre-record buffer: saves 5 to 30 seconds before motion triggers so you catch the approach, not just the action. Adds roughly 10 percent to motion-only size.

For home use, motion-only with a 10-second pre-record buffer gives the best balance of footage coverage and drive life.

How Much Retention Do You Need?

  • 7 days: minimum for a home system. Covers a week of vacation.
  • 14 days: typical default on consumer NVRs. Good for noticing late-reported incidents (scratched car, stolen package).
  • 30 days: recommended for insurance claims and small business. Covers most police report timelines.
  • 60 to 90 days: required for many commercial compliance standards (PCI DSS, some HIPAA environments). Larger drives or NAS needed.
  • 1 year: specialty use (casino, bank vault, high-security warehouse). Requires dedicated VMS server with RAID array.

NVR vs NAS vs Cloud

  • NVR internal drive: cheapest option. 1 or 2 drive bays in most consumer NVRs. Up to 16 TB per bay. Good for home.
  • External NAS (Synology, QNAP): flexible, supports RAID, accessible from any device. More expensive per TB. Right for multi-building setups or when you want footage on a separate device from the cameras.
  • Cloud (Ring, Nest, Arlo, Reolink Cloud): $3 to $20/month per camera. Convenient, no drive management, but costs scale with cameras and lose everything if subscription lapses. Right for 1 to 2 cameras, or as backup alongside local NVR.
  • Hybrid: local NVR + cloud backup of motion events only. Best-of-both approach. Supported on Reolink, Eufy, Amcrest.

Best Hard Drives for NVRs

Do not use a desktop drive. Surveillance-rated drives are tuned for 24/7 writes and multi-stream record. Top picks:

  • WD Purple Pro (1 TB to 22 TB): the standard. 24/7 rated, AllFrame AI support for up to 64 cameras. $25 to $35 per TB.
  • Seagate SkyHawk AI (1 TB to 24 TB): same tier as Purple Pro. ImagePerfect AI firmware for deep learning workloads. Slightly better 4K performance in NVRs with AI plugins.
  • Toshiba S300 Surveillance (1 TB to 10 TB): budget pick. Fine for up to 32 cameras. Slightly shorter warranty (3 years vs 5 on Purple Pro).
  • WD Red Plus (for NAS, not NVR): only pick for Synology/QNAP builds. NASware firmware is tuned for file access, not continuous stream writes.

Avoid: WD Blue, Seagate Barracuda, any shingled magnetic recording (SMR) drive. SMR cannot sustain 24/7 write workload and starts dropping frames within 3 to 6 months.

RAID for Cameras: Yes or No?

  • Single drive: fine for home. A failed drive loses a month of history, not a crime in progress; cameras keep recording (to the new drive once replaced).
  • RAID 1 (mirror): worth it for small business. Two drives, same data; a failed drive does not cost footage. Cuts usable capacity in half.
  • RAID 5 (4+ drives): used in serious office installs. Survives one drive failure, keeps 75 percent of capacity. Overkill for 4 to 8 camera homes.
  • RAID 6 (6+ drives): survives two drive failures. Standard for casino, bank, government. Overkill for small business.

Drive Sizing Cheat Sheet

Pick the drive size by camera count, resolution, and retention target. Use H.265 (standard on 2022+ cameras):

  • 4x 1080p, 14-day, motion: 1 TB drive.
  • 4x 1080p, 30-day, 24/7: 2 TB drive.
  • 4x 4K, 14-day, motion: 2 TB drive.
  • 4x 4K, 30-day, 24/7: 4 to 6 TB drive.
  • 8x 4K, 14-day, motion: 4 TB drive.
  • 8x 4K, 30-day, 24/7: 10 to 12 TB drive.
  • 16x 4K, 30-day, 24/7: 20 TB or 2x 10 TB.

Round up, not down. Drives filling at 95 percent thrash and fail early. Keep 15 to 20 percent headroom.

Frequently Asked Questions

How long does 2 TB hold 4 cameras?

4x 1080p H.265 at 24/7: about 60 days. 4x 4K H.265 at 24/7: about 15 days. Motion-only roughly triples those numbers.

Does H.265 cost CPU in the NVR?

Slightly. Most modern NVRs (Reolink RLN8-410, Hikvision DS-76xx, Dahua NVR41xx) handle H.265 for 8 to 16 channels without issue. Very old NVRs (pre-2018) may struggle with 8+ channels of 4K H.265 decode.

Can I use an external USB drive?

Most NVRs do not support USB for record; the USB port is for firmware updates and backup export. Use an internal SATA drive or an eSATA/network expansion cartridge.

What happens when the drive fills up?

NVRs overwrite oldest footage first (ring buffer). Default on every major brand. You never run out of space; you just lose the older end of the retention window.

Do SSDs make sense for security recording?

No. Camera recording is a high-write, sequential workload. SSDs burn through write endurance in 12 to 24 months. HDDs handle the same load for 5+ years. Skip SSDs unless you need instant seek for AI event search.

How do I calculate my exact storage?

Formula: storage (GB) = cameras x bitrate (Mbps) x days x 10.8. Example: 8 cameras x 6 Mbps x 30 days x 10.8 = 15,552 GB = 15.5 TB.

Bottom Line

For most 4-camera 4K home systems: 4 TB WD Purple or Seagate SkyHawk with H.265 and motion-only recording gives 30 days of history. For 8 cameras at 4K with 24/7 record, step up to 10 to 12 TB. Use surveillance-rated drives, skip SMR and SSDs, and keep 15 percent headroom. For codec math see the 4K vs 1080p comparison. For camera lens matching see the lens guide. For full system picks see best outdoor camera systems.

Security Camera Storage by Resolution and Codec

Security camera storage requirements vary dramatically by resolution and compression. A 1080p camera using H.264 consumes roughly 10 GB per day at continuous recording, while the same camera at H.265 compression uses about 5 GB. Jump to 4K resolution and security camera storage needs roughly quadruple. 15–20 GB per day with H.265, or 30+ GB with H.264. These numbers apply to continuous recording; motion-only recording at 30–40% activity cuts security camera storage requirements roughly in half. The 4K vs 1080p comparison includes detailed bandwidth and security camera storage tables for all common resolutions.

Security Camera Storage: Hard Drive and NVR Planning

For local security camera storage on an NVR or DVR, surveillance-rated hard drives (WD Purple, Seagate SkyHawk) are essential. Standard desktop drives fail prematurely under the 24/7 write cycle that security camera storage demands. A 4-camera 1080p H.265 system needs approximately 2 TB for 30 days of continuous recording, while a 4-camera 4K H.265 system needs 4–6 TB. Larger installations benefit from RAID configurations that provide redundancy. If one drive fails, your security camera storage remains intact on the surviving drives. For expandable security camera storage, NAS-based setups with Synology or Blue Iris allow hot-swapping drives without downtime.

The choice between cloud and local security camera storage also affects planning. Cloud subscriptions shift security camera storage responsibility to the vendor, but limit retention to 30–60 days on most plans and carry monthly fees. Local NVR security camera storage gives you full control over retention periods. Store 90, 180, or even 365 days of footage by sizing your drives accordingly. Hybrid approaches that use local security camera storage for continuous recording and cloud for event-triggered backups offer the best balance of reliability and off-site protection. Industry guidance from NIST and SIA recommends at minimum 30 days of retention for residential systems and 90 days for commercial installations.

Security Camera Storage: Retention Period Planning

How long you keep footage directly determines your security camera storage requirements. Most homeowners target 14–30 days of retention, which strikes a balance between having enough history to review incidents and keeping security camera storage costs reasonable. Businesses typically need 30–90 days, and some regulated industries (banking, healthcare) require 180+ days.

To calculate your security camera storage needs: multiply the daily GB per camera by the number of cameras, then multiply by your desired retention days. A 4-camera 4K H.265 system at 30-day retention needs roughly 2.4 TB of security camera storage, while the same system at 90-day retention needs 7.2 TB. Always add 15–20% overhead to your security camera storage estimate to account for peak activity days and file system overhead.

Expanding security camera storage later is straightforward with the right recorder. Most NVRs accept standard SATA drives. Swapping a 2 TB drive for an 8 TB drive takes 15 minutes and triples your security camera storage retention. NAS-based systems running Synology or Blue Iris can expand security camera storage by adding drives to empty bays without downtime. Planning for expansion from the start. Buying a recorder with extra drive bays even if you do not fill them immediately. Saves the cost and hassle of replacing the entire recorder when your security camera storage runs out.

CCTV Storage Math: Calculating How Much Storage You Need

Calculating how much storage you need for security cameras starts with three inputs: bitrate per camera, frames per second, and number of days of retention. For cameras recording continuously at 4K with a frame rate of 30 fps using H.265 compression, expect ~8 GB per camera per day. Four cameras recording continuously for 30 days require ~960 GB of storage capacity on a hard drive or NVR storage solution. That is why most surveillance system builds start at 1TB of storage or 2TB of storage space for a four-camera system.

A motion detection schedule cuts required storage dramatically. The same four cameras recording only on motion drop to 30-50 GB per camera per day, reducing disk space use by 80 percent. Video quality setting and frame rate also reduce storage: dropping to 15 fps at 1080p shrinks file sizes further. Options for the actual storage medium include an internal HDD in the DVR (typical), a microSD card in the camera itself (used for backup or edge storage), an SD card on specific camera models, cloud storage for off-site backup, or an external hard drive storage expansion for long retention. CCTV cameras with smaller sensors require less storage; 4K CCTV camera systems require more storage. A CCTV storage plan that supports 14 to 30 days of retention is the common requirement; professional surveillance systems with 90+ day retention require more storage and usually a dedicated NAS storage system.

Video Surveillance Storage: Multi-Camera Math and IP Camera Bitrates

Calculating storage requirements for security cameras across multiple cameras is straightforward once you know per-camera bitrate. Four 1080p cameras recording continuously at 4 Mbps each consume roughly 160 GB per day combined; four cameras dropped to 2 Mbps on motion-only cut the amount of storage required by 70%. 4MP cameras at 6 Mbps push the number to 240 GB per day for four cameras. IP cameras over PoE typically run higher bitrates than analog, so video surveillance storage plans for IP camera deployments budget more disk per camera. Surveillance footage at 4K from IP cameras roughly doubles the storage use compared to 1080p.

Additional storage rule of thumb: budget 1TB per camera per month of 1080p continuous recording, or 2TB per camera per month at 4K. For motion-only recording, divide by three. Camera settings matter as much as resolution: 30 fps uses twice the storage of 15 fps. A security camera need for 90-day retention on eight cameras at 4K is close to 16TB of data storage, well into NAS territory. Much space gets wasted when the DVR defaults to continuous 30fps; reducing to 15fps plus motion recording typically saves 60-70% with no meaningful forensic loss. For smaller home builds with four 1080p cameras, a 4TB NVR HDD gives 30 days on motion-only. A security system with a mix of 4MP and 4K cameras should plan each camera’s storage individually.

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