What is the difference between H.264 and H.265 video codecs?

H.265 (HEVC) compresses video 30% to 50% more efficiently than H.264 without quality loss, significantly extending total recording time on the same SD card.

Dash Cam SD Card Recording Time Calculator

Q: How long will a 128GB SD card record on a dash cam?

On average, a 128GB SD card records between 6 to 12 hours of continuous footage. A single 1080p camera using H.265 compression holds around 12 to 14 hours, while a dual 4K setup holds roughly 6 to 8 hours.

Q: Why does my dash cam SD card fill up so fast?

Common causes include high G-sensor sensitivity saving locked emergency files that loop recording cannot delete, continuous 24/7 parking mode recording, or recording at very high bitrates/60 FPS.

Q: What SD card size do I need for a 4K dual dash cam?

For a 4K dual dash cam (Front 4K + Rear 1080p/2K), a minimum of 128GB is recommended, though a 256GB high-endurance card is ideal for longer rolling coverage.

Not sure how many hours of footage your memory card can hold? Whether you are setting up a single 1080p front camera or a multi-channel 4K system, loop recording storage math can be tricky. Video resolution, framerate, compression codecs (H.264 vs. H.265), and emergency file reserves all impact your total recording window.

Use my free Dash Cam Memory Card Calculator to instantly estimate how long your SD card will record before overwriting old video files.

Dashcam Recording Time Calculator

Setup

Select your dash cam

Bitrate quality

SD card size

Cameras & resolution

Estimated recording time

0h 0m

0 Mbps

Combined bitrate

0 GB

Usable capacity*

0 GB

Used per hour

Same settings, other card sizes
Card	Usable	Recording time

*Usable capacity assumes ~19% is unavailable for loop recording. Roughly 7% lost to formatting overhead, plus an added safety margin for space reserved for locked/protected event files and real-world bitrate running a little above the nominal spec. This is a deliberately conservative estimate, checked against manufacturers' own published recording-time tables to stay at or under their figures rather than over them. Bitrate figures come from manufacturer spec sheets, published support-manual bitrate tables, and real-world tests reported by DashCamTalk / BlackboxMyCar, except where a model's note flags an estimate (no official bitrate was published for that exact tier). Actual bitrate varies with firmware, HDR, audio, and scene complexity. The community-run DashCamTalk calculator is a good place to cross-check these numbers.

Dash cam SD card calculator - Listed models

All of the dash cam models listed in the calculator are available to purchase from Drivercam NZ.

How long does a dash cam record on an SD card?

The table below provides a quick estimate for continuous loop recording time based on a standard single-channel (Front Only) setup at 30 FPS:

SD Card Size	1080p Full HD (~12 Mbps)	2K QHD (~27 Mbps)	4K UHD (~60 Mbps)
32 GB	~5.5 hours	~2.5 hours	~1 hour
64 GB	~11 hours	~5 hours	~2 hours
128 GB	~22 hours	~10 hours	~4.5 hours
256 GB	~44 hours	~19.5 hours	~9 hours
512 GB	~88 hours	~39 hours	~17.5 hours

Note: Estimates assume a single-channel (front-only) setup at the camera's maximum/highest bitrate setting. Lower bitrate settings (Low/Medium) will roughly double or triple these times. Use the calculator above for other tiers. Multi-channel setups (front + rear) will use storage faster, roughly in proportion to the added channel's bitrate.

Frequently Asked Questions

How acurate is the calculator?

The dash cam SD card calculator has been designed to give a conservative recording time. In the real world you may find that you get more footage, but I worked on the assumption that manufactures tend to publish the best possible results. All calculations are done with AI, but have been proof checked by a Human (myself). I expect the results to me accurate to within 10% under normal conditions, but please note that the times are an estimate and not guaranteed.

How long will a 128GB SD card record on a dash cam?

On average, a 128GB SD card records between about 4.5 and 22 hours of continuous footage, depending heavily on your setup. A single 1080p front-only camera can stretch to around 22 hours, whereas a single 4K front-only camera fills the same 128GB card in roughly 4.5 hours. Add a rear camera and that drops further — a 4K front + 1080p rear dual system records for around 3 hours 40 minutes on 128GB, or a 4K front + 2K rear system around 3 hours before the oldest footage starts getting overwritten.

Why does my dash cam SD card fill up so fast?

If your SD card fills up faster than expected or throws a “Memory Card Full” error, check these common causes:

G-Sensor Sensitivity is Too High: Potholes and hard braking trigger emergency file locks. These locked clips are saved to a protected folder that loop recording cannot delete, reducing usable loop space.
Parking Mode Video: 24/7 parking surveillance continuously writes motion or time-lapse files to the card.
High Bitrate Settings: Recording at maximum bitrate or 60 FPS creates much larger file sizes per minute.

What is loop recording and how does it affect storage?

Loop recording breaks video footage into short segments (usually 1-, 3-, or 5-minute clips). When the SD card reaches maximum capacity, the dash cam automatically overwrites the oldest unlocked file with the newest clip. You don’t need to manually clear the card unless locked emergency files accumulate.

What SD card size do I need for a 4K dual dash cam?

For a 4K dual dash cam (Front 4K + Rear 1080p/2K), I recommend a minimum of 128GB, though a 256GB card is a much better fit for daily use. At maximum bitrate, a 4K + 1080p dual system uses roughly 9GB per hour combined, so a 128GB card gives only around 3 hours 40 minutes of rolling coverage, where a 256GB card roughly doubles that to about 7 hours 20 minutes, which comfortably covers a full day of commuting before looping.

What is the difference between H.264 and H.265 (HEVC)?

H.265 (High Efficiency Video Coding) is a newer compression standard that compresses video up to 30% to 50% more efficiently than H.264 without sacrificing visual quality. Choosing H.265 in your dash cam settings instantly extends your recording time on the exact same memory card.

Do I need a high-endurance SD card for a dash cam?

Yes. Dash cams continuously write and overwrite data at high temperatures, which wears out standard SD cards quickly and leads to corrupted footage. Always look for cards explicitly labeled “High Endurance” or “Max Endurance” using MLC/TLC flash memory.