How long will a 4TB NVR record?
By Devin Chua · Data checked by Owen Nakamura · Updated A 4 TB NVR records four 1080p H.265 cameras for about 32 days continuously — or four 4K cameras for roughly 8 days. That is usable 4 TB; if the drive is in a RAID array with parity, the recording time drops by whatever the array gives up to redundancy. Set your cameras and codec below for the real number.
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Days 1 TB records, by resolution and codec (24/7)
| Resolution | Codec | 1 camera | 4 cameras |
|---|---|---|---|
| 1080p (2MP) | H.265 / HEVC | 32 days | 7.9 days |
| 1080p (2MP) | H.264 | 16 days | 4.0 days |
| 2K / 4MP | H.265 / HEVC | 18 days | 4.4 days |
| 2K / 4MP | H.264 | 9 days | 2.2 days |
| 4K / 8MP | H.265 / HEVC | 8 days | 2.0 days |
| 4K / 8MP | H.264 | 4 days | 1.0 days |
Per 1 TB of usable space, recording 24/7 with ~20% overhead. Motion-only recording extends these in proportion to how quiet the scene is.
Size it exactly
Pre-filled for this question — change any input to model your own setup.
12.7 TB of footage over 30 days, +20% overhead = 15.2 TB
What 4 TB actually buys you
Four terabytes is a common single-drive NVR size, and how long it lasts is set by total daily footage. Four 1080p H.265 cameras write roughly 125 GB a day together, so 4 TB (4,000 GB) covers about a month. Four 4K cameras write four times that — about 500 GB a day — so the same 4 TB is full in a bit over a week.
One catch NVR buyers miss: if that 4 TB sits behind RAID, its usable capacity is less than 4 TB. A single drive gives the full 4 TB but no redundancy; two 4 TB drives in RAID 1 give 4 TB usable but survive a failure; RAID 5 needs three or more. The calculator converts to usable capacity honestly.
Extending a 4 TB recorder
If 4 TB is not enough for your retention, the levers are the usual ones: switch cameras to H.265 (about double the days), drop from 4K to 1080p where detail is not critical, record on motion for quiet scenes, or — the real fix — fit larger surveillance drives. The calculator will size the drive capacity and count you actually need and price it live.
Frequently asked questions
How many days will a 4TB NVR hold?
About 32 days for four 1080p H.265 cameras at 24/7, or roughly 8 days for four 4K cameras. Fewer cameras or H.264 change it proportionally; the calculator computes your exact figure from bitrate, hours and retention.
How many cameras can a 4TB NVR support?
Storage is not the limit on camera count — the NVR's channels are — but 4 TB comfortably stores about four 1080p cameras for a month, or eight for a couple of weeks. For 4K or longer retention you will want more capacity.
Is 4TB enough for an NVR?
For a few 1080p cameras with a month of retention, yes. For 4K cameras or many channels, 4 TB fills quickly — often in days. Size it with the calculator and step up to larger surveillance drives if your retention needs it.
Should NVR storage use RAID?
For more than one drive, yes — RAID 5 or SHR survives a drive failure without losing weeks of footage, at the cost of one drive of capacity. A single 4 TB drive has no redundancy, so a failure loses everything. The calculator shows usable capacity per RAID level.
Read more
Devin Chua works out which drives, RAM and NVMe cache fit which NAS model at nasdrives.ca, and what the RAID choice means for usable capacity, checked against what is in stock on Amazon.ca.
Data checked by Owen Nakamura, Technical editor (data checking)