Calculator

Security camera storage calculator

Updated October 7, 2026

Enter your cameras, resolution, codec, recording mode and days of history to see how many gigabytes or terabytes you need, and what microSD card or NVR drive size to buy.

Number of camerascameras recording

Resolution check your camera’s spec sheet

Video codec H.265 usually needs a lower bitrate

Frames per secondfps, 1 to 30

Bitrate in the camera’s video settings

Bitrate per cameramegabits per second (Mbps)

Recording mode events: only clips are saved

Event video per dayhours per camera (events mode)

Days of history to keepdays, 1 to 365

Where it is stored shared disk or one card per camera

Next steps

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How the calculation works

Video storage is bitrate multiplied by time. A camera that streams at 1 megabit per second (Mbps) writes 1,000,000 bits each second, which is 0.125 megabytes. The calculator uses these steps:

GB per hour per camera = bitrate (Mbps) ÷ 8 × 3,600 ÷ 1,000. A 2.4 Mbps stream is 0.3 MB a second, or about 1.08 GB an hour.
GB per day = GB per hour × hours recorded. Continuous recording is 24 hours. In events mode you enter how many hours of motion clips your camera typically saves each day.
Total = per-day GB × number of cameras × days of history, plus 15% headroom so the disk never runs completely full and so a few high-motion days do not push old footage out early.
The recommendation is the next standard size: 32 to 1,024 GB for microSD cards, and 1 TB to 24 TB for a recorder drive.

Where the estimated bitrate comes from

If you pick “Estimate it for me”, the tool starts from typical H.264 bitrates at 15 frames per second: about 1.5 Mbps at 1 MP, 2.5 Mbps at 2 MP, 4 Mbps at 4 MP, 5 Mbps at 5 MP and 8 Mbps at 8 MP. H.265 (HEVC) is a newer codec that is commonly reported to need about a quarter to a half less data at similar quality, so the tool uses 60% of the H.264 figure. Bitrate is then scaled gently with frame rate: lower than 15 fps lowers it, higher than 15 fps raises it. These are planning numbers. Cameras vary, many let you pick a fixed or variable bitrate, and busy scenes produce more data. If your camera’s video settings or app show the bitrate, choose “I know my camera’s bitrate” and type it in.

Worked examples

Example 1: four 4 MP cameras on an NVR. The defaults: H.265 at 15 fps gives an estimated 2.4 Mbps, which is 25.9 GB per camera per day if recorded continuously. Four cameras write about 104 GB a day, so 14 days is about 1.45 TB. Adding 15% headroom gives 1.67 TB, and the next standard drive is 2 TB.

Example 2: two 1080p cameras on microSD cards, motion clips only. Choose 2 MP, H.264, 15 fps (2.5 Mbps estimate), events mode with 3 hours a day, 30 days, and microSD. One camera writes 3.4 GB a day, or 101 GB over 30 days. With 15% headroom that is 116 GB, so a 128 GB card in each camera is enough.

Common mistakes

Using the marketing resolution and ignoring the bitrate. Storage follows bitrate, not megapixels alone. Two 4 MP cameras can differ by a factor of two depending on codec and settings.
Sizing a card for continuous recording when the camera only saves clips. Many battery and low-cost cameras only record events, so continuous mode will overstate what you need.
Forgetting that the sub-stream and audio add a little. Audio is small, but some recorders also store a second, lower-quality stream. Headroom covers this.
Buying the biggest microSD card without checking the camera. Cameras list a maximum supported size, and a card larger than that may not work at all.
Ignoring wear. A standard card that is rewritten every day can fail in months. Cards labeled high endurance or for surveillance are built for this load.
Skipping the network check. Several cameras streaming to a recorder at once can overload Wi-Fi. The table shows the combined load; our guide on PoE vs Wi-Fi cameras covers when to wire them.

Local storage is also how you avoid a monthly plan: see security cameras with no monthly fee for the full cost comparison.

Frequently asked questions

How much storage do I need for one security camera?

A 1080p camera recording continuously at about 2.5 Mbps writes roughly 27 GB a day, so a 128 GB card holds under 5 days and a 512 GB card about 19 days. Motion-only recording stretches that to weeks or months, depending on how often the camera triggers.

Is continuous or motion recording better for storage?

Motion recording uses far less space, though how much depends on how often the camera triggers, but it can miss the seconds before an event and anything the camera fails to detect. Continuous recording keeps everything, at the cost of a much larger disk or card.

Does H.265 really save space?

Usually yes: H.265 (HEVC) is commonly reported to need about 25% to 50% less data than H.264 at similar quality. Your camera, recorder and app must all support it, and some phones or older software cannot play it back.

What size microSD card should I buy for a security camera?

Work out one camera’s total for the days you want, add about 15%, and round up to 64, 128, 256 or 512 GB, never above your camera’s stated maximum. Choose a high endurance card if the camera records continuously.