NVR Storage Calculator: Estimate CCTV Hard Drive Size

Key takeaways:

• Check storage before buying or upgrading a drive. Camera count, recording mode, codec, and retention days can change needed TB more than resolution.
• Continuous recording fills a drive much faster than event recording. Motion clips may keep footage longer on the same drive.
• H.265 usually uses less storage than H.264 at similar video quality. That codec setting can change the drive size recommendation.
• A 4 TB drive does not give you 4 TB of usable space after formatting. The calculator accounts for usable capacity and headroom.
• Treat the result as a planning estimate. Scene complexity, motion level, lighting, and device settings can change actual storage use.

The NVR storage calculator helps you check hard drive size before you buy or upgrade one. Resolution matters, but it is only one part of storage. Four cameras saving event clips can use less space than four cameras recording all day. Add camera count, recording style, and retention days, and the tool returns total storage, drive size, and drive count.

Results are estimates only. Actual storage use may vary based on scene complexity, motion frequency, lighting, resolution, frame rate, compression, recording mode, firmware behavior, and specific device settings over time.

What does the NVR storage calculator estimate?

The calculator is for local video storage planning. A small setup may need only a few saved days. A larger wired system may need weeks of footage. The estimate shows which setting is raising the TB number.

It covers three setup types:

• PoE NVR Security System S4 Max: A wired system built for recording 24 hours a day.
• eufy HomeBase 3: A hub for wireless battery cameras that usually record when motion or events are detected.
• Generic NVR: A mode for any brand, with resolution and hard drive size set by the user.

How should you use the calculator?

Start with the settings you know. If one input is still uncertain, pick the closest option and adjust it later. The result depends on the setup details you enter.

• Camera model or resolution. This sets the default bitrate, which is how much data each camera writes. In eufy modes, choose the model. In Generic mode, choose the resolution.
• Number of cameras. The range is 1 to 64. More cameras means more video to store.
• Recording mode. Continuous recording uses hours per day. Event recording uses daily event count and seconds per clip.
• Retention days. This is how long footage stays before it is overwritten.
• Codec. H.265 or H.264 changes file size, sometimes by a lot.
• Manual bitrate. If you know the exact Mbps per camera, enter it instead of using the default.

After entering the inputs, check total TB first. Then compare suggested drive size with the storage included in your device. eufy PoE NVR Security System S4 Max ships with a 2TB drive. HomeBase 3 does not include a drive.

How is NVR storage calculated?

The math is simple enough to follow by hand. Camera count, retention days, and recording mode make the biggest difference.

1. Data per camera each hour, in GB = bitrate (Mbps) × 3,600 ÷ 8 ÷ 1,024
2. Total recording hours. For continuous mode, cameras × hours per day × retention days. For event mode, cameras × events per day × seconds per clip ÷ 3,600 × retention days.
3. Storage needed, in TB = data per camera each hour × total hours ÷ 1,024

Drive labels need a small adjustment. A 4 TB drive is labeled with decimal TB, so the formatted space is usually lower than 4 TB. Using nominal capacity × 0.9095 puts that drive at about 3.64 TB usable.

The calculator also plans around a 90 percent fill level, so drive size is storage needed ÷ 0.9.

The table gives a quick sense of scale.

Use the table for a quick check. Before choosing a drive, run the calculator with your camera count, codec, mode, and retention days.

How much does H.265 change storage use?

Codec can change drive size more than many people expect.

H.265 usually stores similar video quality in a smaller file than H.264. Choose H.264 in the calculator, and the default bitrate rises to match larger files.

Some eufy cameras already have a default codec profile in the calculator:

Your camera settings still matter. If the camera is set differently, change the codec or enter the bitrate.

Conclusion

The NVR storage calculator helps you plan storage with fewer guesses. Check camera count, recording mode, codec, and retention days before choosing a drive. That check can help you avoid paying for capacity you may not use, while lowering the chance that older clips are overwritten sooner than expected.

FAQs

How much storage do I need for 4 cameras in 30 days?

For four cameras over 30 days, resolution, codec, bitrate, and recording mode matter. Four 4K cameras recording continuously in H.265 often land near 9.9 TB. Event recording or lower resolution can bring the number down.

What is the difference between continuous and motion or event recording?

Continuous recording keeps a full timeline, which helps when you need to review a day. It also uses more storage. Event recording saves clips after motion is detected, so it is lighter on the drive. Moments that do not trigger recording may not be saved.

Can I upgrade the hard drive later?

In most setups, yes. eufy PoE NVR Security System S4 Max has a bay for a 3.5 inch drive and supports up to 16 TB, so the included 2 TB drive can be replaced later. HomeBase 3 also supports an expansion drive.

What does Generic mode do compared with the eufy presets?

Generic mode removes the eufy model defaults. You choose the resolution and drive size. Use it for other NVR brands, older cameras, or mixed systems where the exact preset is not listed.

How long will a 2TB NVR record?

A 2 TB drive can last weeks in a light event recording setup. With several 4K cameras recording continuously, it may last only days. Camera count and recording mode usually move the number most, so the calculator is better for your setup.

Is HDD or SSD better for an NVR?

Both can work, but cost per TB often decides. Surveillance rated hard drives are common for continuous recording because they are built for steady writing and usually cost less at larger capacities. SSDs are quiet and fast, but often cost more.