CCTV Storage Guide: What Size Hard Drive Does Your NVR or DVR Need?
How much storage does a CCTV system need? For most UK jobs, a 4-camera 1080p DVR recording continuously for 30 days needs roughly 5–6 TB, while an 8-camera 4MP NVR over the same period can need 15 TB or more — but the honest answer is "it depends", and this guide shows you exactly what it depends on. We look at the calculation every installer should understand, worked CCTV storage examples for typical DVR and NVR systems, the hard drive sizes we stock and ship, the ongoing 2026 hard drive shortage that is pushing prices up, and how to use Hikvision's own storage calculator to size a job precisely before you quote it.
At a glance
- CCTV storage (TB) ≈ cameras × bitrate (Mbps) × 0.0108 × hours/day × days
- Rule of thumb (H.265, 24/7, 30 days): 4×1080p ≈ 5–6 TB; 8×4MP ≈ 15 TB; recording on motion roughly halves it
- We stock surveillance hard drives in 1 TB, 2 TB, 4 TB, 6 TB, 8 TB and 10 TB — other sizes available to order
- Choose your drive size at the basket when you buy any DVR or NVR from netviewcctv.co.uk
- 2026 note: a global hard drive shortage has pushed prices up sharply — size correctly and order early
- Use the free Hikvision HiTools storage & bandwidth calculator to size any job exactly
How much storage does a CCTV system need?
A CCTV system needs enough hard drive space to hold every camera's video stream for the number of days the customer wants to keep footage — and that figure is driven by four things: how many cameras, at what resolution and bitrate, recording continuously or on motion, and for how many days. There is no single "right" drive size because a 4-camera 1080p domestic system and a 16-camera 4K retail system can differ by a factor of ten. What every installer can do is calculate it in under a minute, and that is where this guide starts. Getting it right at the quoting stage avoids the two classic mistakes: undersizing so the customer loses footage before their retention window, or oversizing and wasting money on a drive that is now, in 2026, a genuinely expensive component.
The formula: how CCTV storage is calculated
CCTV storage is worked out by multiplying each camera's bitrate by the recording time and the number of cameras, then converting bits to terabytes. The standard formula used across the industry is Storage (GB) = bitrate (Mbps) × 3600 × hours per day × days × cameras ÷ 8 ÷ 1000 (Reolink CCTV storage formula). A useful shortcut is that one continuous 1 Mbps stream uses about 0.0108 TB (10.8 GB) per camera per day, so you can multiply that by each camera's bitrate in Mbps, by the number of days, and by the number of cameras. For example, four cameras at 4 Mbps recording 24/7 for 30 days works out at 4 × 4 × 0.0108 × 30 ≈ 5.2 TB. The maths is simple; the accuracy comes from choosing a realistic bitrate.
What drives the number: resolution, bitrate and compression
The single biggest variable is bitrate, and bitrate rises with resolution, frame rate and scene complexity. As a working guide for Hikvision and HiLook cameras using H.265, a 2MP (1080p) camera runs at roughly 2–4 Mbps, a 4MP camera at roughly 4–6 Mbps, and an 8MP (4K) camera at roughly 8–10 Mbps at full frame rate. Two settings cut those figures dramatically. H.265+ (Smart Codec) applies extra compression to static scenes and can reduce bitrate by half or more compared with H.264. Frame rate matters too: dropping from 25 fps to 12 fps on a car park or corridor roughly halves the data with no loss of evidential value. Always size storage on the bitrate you will actually configure, not the camera's theoretical maximum — and if you are still choosing cameras, our Hikvision camera buyer's guide covers resolution choice in detail.
Continuous vs motion recording: the biggest lever
Recording on motion or schedule instead of 24/7 is the fastest way to cut storage, typically by 40–70% on a normal site. A camera watching a rear yard that only sees activity a few times an hour spends most of the day recording nothing of interest, so event-based recording — ideally triggered by AcuSense human/vehicle detection rather than raw pixel change — stores only what matters and slashes the drive size you need. On a busy shop floor or a public footpath, continuous recording remains the safe choice because there is almost always motion. A common professional compromise is continuous recording at a low frame rate with a higher frame rate triggered on motion. Whatever you choose, size the drive for the recording mode you will commission, and add roughly 20% headroom for formatting, indexing and busy days.
Worked examples: 4, 8 and 16-camera systems
The table below sizes typical UK systems using H.265, 24/7 continuous recording and 30 days retention, with the "on motion" column showing roughly half that for event-based recording. Use it as a starting point, then confirm with the calculator.
| System | Cameras & bitrate | 30 days continuous | 30 days on motion | Drive to fit |
|---|---|---|---|---|
| 4-camera 1080p DVR | 4 × 2MP @ 4 Mbps | ≈ 5.2 TB | ≈ 2.6 TB | 6 TB (4 TB on motion) |
| 4-camera 4K NVR | 4 × 8MP @ 8 Mbps | ≈ 10.4 TB | ≈ 5.2 TB | 10 TB (6 TB on motion) |
| 8-camera 4MP NVR | 8 × 4MP @ 6 Mbps | ≈ 15.6 TB | ≈ 7.8 TB | 2 × 8 TB (8 TB on motion) |
| 16-camera 4MP NVR | 16 × 4MP @ 6 Mbps | ≈ 31 TB | ≈ 15.6 TB | Multi-bay, 4 × 8 TB |
Two things stand out. First, 4K and higher camera counts push you past what a single drive can hold, which is why recording mode and multi-bay recorders matter. Second, event-based recording changes the whole picture — the same 8-camera system drops from two drives to one when it records on motion.
Hard drive sizes we stock (and the drive-with-recorder option)
Netview holds surveillance hard drives in six capacities ready for same-day dispatch, and lets you add the right one to any recorder at the point of purchase. The stocked range is 1 TB, 2 TB, 4 TB, 6 TB, 8 TB and 10 TB, with larger capacities available to order. The important convenience for installers is that when you buy any DVR or NVR from netviewcctv.co.uk you can choose your hard drive size in the basket — the recorder arrives with the drive fitted and formatted, so there is nothing to source separately and nothing to open up on site. Match the capacity to the worked example above: a 4-camera 1080p DVR pairs naturally with a 6 TB drive for 30 days continuous, a 4-camera 4K NVR with a 10 TB drive, and larger systems with a multi-bay recorder carrying two or more drives.
| Drive | Typical fit (H.265, 30 days) |
|---|---|
| 1 TB / 2 TB | 1–4 cameras on motion, or short retention |
| 4 TB | 4 × 1080p on motion, or 4 cameras < 20 days |
| 6 TB | 4 × 1080p continuous, 30 days |
| 8 TB | 8 × 4MP on motion, or 4 × 4MP continuous |
| 10 TB | 4 × 4K continuous, or headroom for growth |
Use the Hikvision HiTools storage calculator
For an exact figure, Hikvision provides a free online storage and bandwidth calculator that sizes any job in seconds. The Hikvision HiTools Designer storage & bandwidth calculator lets you enter the number of cameras, resolution, bitrate, frame rate, recording schedule and retention days, then returns both the total storage required and the bandwidth the system will generate. It is the quickest way to confirm a quote and to demonstrate to a customer why a particular drive or multi-bay recorder is necessary. You can also work it the other way round — enter the drive size you intend to fit and it tells you how many days of recording you will get, which is invaluable when a customer asks "how long will it keep?" For Hikvision's own guidance on the method, see their storage calculation support article, and find more sizing tools on our Hikvision Tools Hub.
The 2026 hard drive shortage: prices and availability
There is a genuine global shortage of hard drives in 2026, and it is pushing surveillance drive prices up and lead times out. The cause is AI: hyperscale data centres have bought up hard drive production to store enormous volumes of training data, and Western Digital and Seagate have reported their 2026 output effectively sold out, with orders booked into 2027 and 2028 (Yahoo Finance). Prices have climbed sharply — industry reporting puts high-capacity HDDs up around 46% since late 2025, with some models rising more (WinBuzzer). For installers the practical takeaways are simple: size storage correctly rather than over-buying, order drives and recorders early on larger projects rather than assuming next-day availability, and lock in the drive with the recorder while stock is on the shelf. Netview holds surveillance drive stock across all six capacities and dispatches same day on stocked lines, but the market rewards planning ahead.
Why surveillance-rated drives, not desktop drives
Always fit a surveillance-rated hard drive such as Seagate SkyHawk in a DVR or NVR — a desktop drive will fail early under 24/7 recording. The difference is workload rating: a typical desktop drive is designed for around 55 TB of writes per year and roughly eight hours a day of use, whereas surveillance drives are built for continuous write-intensive duty, with SkyHawk rated up to 180 TB/year and the larger SkyHawk AI models higher still (CCTV Aware). Surveillance firmware is also tuned to prioritise smooth, dropped-frame-free recording of multiple simultaneous streams, and to support the higher camera counts a modern NVR handles. Put a desktop drive in a recorder and it can develop bad sectors within months; the small saving is not worth the lost footage. Every hard drive Netview supplies for CCTV is a surveillance-grade drive built for the job.
How many drives can a recorder take?
The number of drives a recorder accepts is set by its bay count, which is usually encoded in the model number. Hikvision K-series recorders follow a clear pattern: a K1 model such as the DS-7604NXI-K1/4P(D) or the DS-7608NXI-K1/8P(D)/Alarm takes a single drive, a K2 two drives, and a K4 such as the DS-7716NXI-K4(D) takes four. Enterprise recorders such as the iDS-9632NXI-M8/X carry eight bays for the largest estates. For DVRs, the HiLook DVR-208U-M1(C) and DVR-216U-M2(C) are single and dual-bay respectively, while the value DVR-204Q-M1(E) takes one drive. If a single large drive will not hold your calculated storage, step up to a multi-bay recorder rather than exceeding the drive's rating — and for choosing the recorder itself, our Hikvision NVR buyer's guide and AcuSense DVR guide walk through the range.
Installer tips to cut storage cost
You can often halve the drive a job needs without losing evidential quality by tuning a few settings. Turn on H.265+ (Smart Codec) on every camera that supports it; record on AcuSense human/vehicle detection instead of continuous where the site allows; drop the frame rate on low-activity views to 12–15 fps; and set a sensible retention target — 30 days suits most commercial jobs, but check whether the customer's insurer or sector actually requires more. Configuring a lower-bitrate sub-stream for continuous recording with a full-quality main-stream triggered on motion is a proven way to stretch a drive. With drive prices elevated in 2026, these settings are not just good practice — they directly reduce the bill of materials on every quote. For recorders that make footage easy to find afterwards, the Hikvision K/VPro AcuSeek range adds natural-language search, and the DeepinView camera guide covers edge analytics that make event recording smarter.
Frequently asked questions
Q: What size hard drive do I need for a 4-camera CCTV system?
A: For four 1080p cameras recording continuously in H.265 for 30 days, budget around 5–6 TB, so a 6 TB drive is the natural fit; recording on motion instead brings that down to roughly 2.6 TB, where a 4 TB drive suffices. Four 4K cameras need about 10 TB continuous.
Q: How much storage do I need for 30 days of CCTV?
A: It depends on cameras, resolution and recording mode — as a guide, an 8-camera 4MP NVR recording 24/7 needs about 15 TB for 30 days, or roughly half that on motion. Use the Hikvision HiTools calculator to confirm the exact figure for your configuration.
Q: Can I use a normal desktop hard drive in a DVR or NVR?
A: No — fit a surveillance-rated drive such as Seagate SkyHawk. Desktop drives are rated for around 55 TB/year and part-time use, and can fail within months under continuous CCTV recording, whereas surveillance drives are built for 24/7 write-intensive duty.
Q: Do I have to buy the hard drive separately?
A: No. When you buy any DVR or NVR from netviewcctv.co.uk you can choose the hard drive size in the basket and the recorder ships with the drive fitted and formatted, ready to install.
Q: Why are hard drives more expensive in 2026?
A: A global shortage driven by AI data-centre demand has sold out much of Western Digital and Seagate's 2026 production, pushing high-capacity drive prices up around 46% since late 2025 and extending lead times. Sizing correctly and ordering early is the sensible response.
Q: How do I calculate CCTV storage myself?
A: Multiply each camera's bitrate in Mbps by 0.0108 to get TB per camera per day, then by the number of days and cameras. For an exact figure including bandwidth, use the free Hikvision HiTools storage calculator.
Buy DVRs, NVRs and surveillance hard drives from Netview — choose your drive size in the basket and your recorder ships fitted, formatted and ready to install. We hold 1–10 TB surveillance drives in stock in Leicester with same-day dispatch on stocked lines and trade pricing for installers. Order online at netviewcctv.co.uk.
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