microSD Card Recording Time Chart
A 128 GB microSD card holds about 3.7 days of continuous 4MP H.265 recording, or about 29.4 days if only 3 hours a day of motion clips are kept, and a standard-endurance card written to continuously for months routinely fails, often without warning.
These figures come from this site's recording-days arithmetic: a card's usable capacity divided by the megabytes a camera writes per hour at a given bitrate and hours-per-day of recording. The card sizes and resolutions are inputs you can change on the calculator; the numbers below are fixed examples so the table itself carries the answer.
Motion-only figures assume 3 hours a day of actual triggered footage, which is a reasonable planning number for a moderately busy exterior camera and not a published standard. A camera on a quiet interior door might trigger for 20 minutes a day; one facing a sidewalk might trigger for 6 hours. Use the calculator with your own camera's activity log if you have one.
| Capacity | 2MP continuous | 2MP motion-only | 4MP continuous | 4MP motion-only | 8MP/4K continuous | 8MP/4K motion-only |
|---|---|---|---|---|---|---|
| 32 GB | 1.4 days | 11 days | 0.9 days | 7.3 days | 0.5 days | 3.7 days |
| 64 GB | 2.8 days | 22 days | 1.8 days | 14.7 days | 0.9 days | 7.3 days |
| 128 GB | 5.5 days | 44.1 days | 3.7 days | 29.4 days | 1.8 days | 14.7 days |
| 256 GB | 11 days | 88.2 days | 7.3 days | 58.8 days | 3.7 days | 29.4 days |
| 512 GB | 22 days | 176.4 days | 14.7 days | 117.6 days | 7.3 days | 58.8 days |
| Resolution | H.264 (typical) | H.265 (typical) |
|---|---|---|
| 2MP (1080p) | 4 Mbps | 2 Mbps |
| 4MP (1440p) | 6 Mbps | 3 Mbps |
| 5MP | 8 Mbps | 4 Mbps |
| 6MP | 10 Mbps | 5 Mbps |
| 8MP (4K) | 12 Mbps | 6 Mbps |
| 12MP | 16 Mbps | 8 Mbps |
How is recording days calculated here?
The arithmetic is fixed: bitrate in Mbps converts to megabytes per hour, multiplied by hours recorded per day, divided into the card's usable capacity after overhead. That part is standard arithmetic and will not vary between sites doing it correctly. What varies is the bitrate assumed for a resolution, which is a scene-dependent convention rather than a fixed number, so treat every day count here as a planning estimate rather than a guarantee.
Why does a card recording continuously wear out?
Consumer microSD flash is built around occasional writes, not a camera looping over the same cells for months at a time. Manufacturers sell a separate high-endurance line specifically because standard cards degrade under constant overwrite and can start dropping or corrupting the oldest footage, sometimes with no error shown to the user until playback is attempted. A card rated for continuous video recording is not an upsell; it is a different flash and firmware pairing for a genuinely different workload.
- Standard consumer cards are rated for occasional photo or file storage, not weeks of unbroken loop recording.
- High-endurance cards use flash and firmware built for continuous overwrite cycles.
- A failing card in continuous mode can silently drop recent footage rather than refusing to write.
The gear that matches this answer
SanDisk 128GB High Endurance Video microSDXC Card with Adapter
$36.99Half the capacity at well under half the price, which is enough when the card is a fallback for a network outage rather than the primary store.
- Capacity
- 128 GB
Prices change often.
SanDisk 256GB High Endurance microSD Card with Adapter
$69.99The card most commonly specified by camera makers for continuous recording, and the capacity that gives a single 4K camera roughly a week.
- Capacity
- 256 GB
Prices change often.
SanDisk 512GB High Endurance microSD Card with Adapter
$123.99The largest high endurance card here, and the only realistic way to get a fortnight of continuous 4K out of a single camera with no recorder at all.
- Capacity
- 512 GB
Prices change often.
PNY 256GB PRO Elite High Endurance microSDXC Flash Memory Card
$79.99A direct alternative at the same capacity, worth checking when the SanDisk is out of stock.
- Capacity
- 256 GB
Prices change often.
TEAMGROUP High Endurance 256GB microSDXC UHS-I U3 V30, Designed for Monitoring
$59.99A V30 speed rating, which is the class that sustains a 4K write without dropping frames.
- Capacity
- 256 GB
Prices change often.
Common questions
Does doubling my card size double my recording days?
Yes, capacity and recording days scale directly once resolution and hours per day are fixed. Moving from a 128 GB card to a 256 GB card at 4MP continuous goes from 3.7 days to 7.3 days, exactly double. The only things that change that ratio are a different bitrate, a different resolution, or a different number of hours recorded per day.
What does motion-only mean in this table?
It assumes 3 hours a day of actual triggered clips get written, which is a planning convention rather than a published figure. A busy exterior camera on a sidewalk can trigger for far more than 3 hours a day; a quiet interior door camera can trigger for far less. Check your own camera's event history for a better number before sizing a card around it.
Why does resolution affect card life so much?
Higher resolution means more pixels to encode every frame, which raises the sustained bitrate and therefore the megabytes written per hour. At this site's H.265 assumptions, an 8MP (4K) camera writes three times the bitrate of a 2MP camera, so the same card lasts a third as long at 4K as it does at 1080p, all else being equal.
Should I trust a card that is not marked high endurance for continuous recording?
Not for a camera that records around the clock. Continuous recording writes and overwrites the same cells for months without a break, which is the exact workload standard consumer cards are not built for. A card marked high endurance, or one specifically sold for dash cams or security cameras, uses flash designed for that pattern and is the safer choice for continuous mode.
Is H.265 always the better choice for card longevity?
For card life, yes: H.265 typically runs at roughly half the bitrate of H.264 at the same resolution, which roughly doubles the days a card holds before overwriting. The trade-off is that H.265 needs a camera and viewing app that both support it properly, and very old NVR software sometimes only handles H.264 cleanly.
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Keep going
Before you point a camera at anything. Aim cameras at your own property and your own boundary, never into a neighbour's windows or across their garden. Cameras in bedrooms, bathrooms, or anywhere else a person reasonably expects privacy are a serious legal problem, and that includes guests, lodgers and anyone who works in your home. Audio is legally different from video, many US states require the consent of every party to a recorded conversation, and several recorders capture audio by default, so check your own state before you enable it. Some places require visible notice that recording is taking place, and landlords and homeowner associations often impose their own rules on top. This is researched general information and not legal advice, and the law varies by state and by country.
And once it is installed. Change every default password, keep the firmware updated, and be clear with yourself about where the footage goes: a cloud camera means a third party holds recordings of your home, while a local recorder keeps them in your house. That is a genuine buying consideration, not a technicality.