Dash Cam Loop Recording Calculator
A dash cam can record for hours, but the amount of footage it keeps depends on more than the size printed on the memory card. Video quality, the number of cameras, and files that cannot be overwritten all affect how quickly available storage fills up. The Dash Cam Loop Recording Calculator estimates how much footage your card can retain before the oldest unprotected clips begin to be overwritten.
Use the estimate to compare memory card capacities, recording settings, and single- or dual-camera setups. The result is an approximation of the footage retained in the space available for loop recording, expressed in hours.
What the Dash Cam Loop Recording Calculator does
The dash cam loop recording calculator estimates the recording time available from three inputs: memory card capacity, the percentage of that capacity available for loop recording, and the combined recording bitrate of all cameras.
Loop recording lets a dash cam continue recording when its available storage fills up. It generally does this by replacing the oldest unprotected recordings with new footage. The calculated Estimated Recording Time is an estimate of how much footage can be retained in the available loop-recording space before that replacement begins.
For example, if the result is approximately 12 hours, the available space can hold roughly 12 hours of footage at the entered bitrate. Once the space fills, the camera can continue recording by overwriting older eligible clips. The result does not tell you the length of each individual video file or how long the camera can continue operating after overwriting starts.
How to use the Dash Cam Loop Recording Calculator
Enter the following information to estimate your dash cam’s recording time:
- Memory card capacity (GB): Enter the advertised capacity of the card in gigabytes. For example, enter 128 for a 128 GB card.
- Capacity available for loop recording (%): Estimate the percentage of the card that is available for ordinary loop recordings. Allow for space used by protected clips, other files, and storage overhead.
- Combined recording bitrate (Mbps): Enter the total recording bitrate in megabits per second. If multiple cameras record at the same time, add their bitrates together.
The calculator displays Estimated Recording Time in hours, rounded to two decimal places. If you are unsure about a setting, check your dash cam’s documentation or recording settings and use an estimate. You can also compare several inputs to see how a change in card capacity or bitrate affects the result.
For a dual-camera setup, an illustrative assumption might be 12 Mbps for the front camera and 8 Mbps for the rear camera. In that case, enter a combined bitrate of 20 Mbps. These sample rates are assumptions, not universal settings; your cameras may record at different rates.
How the Dash Cam Loop Recording Calculator formula works
The calculation divides the storage available for loop recording by the combined rate at which footage uses that storage. It uses decimal units: 1 GB equals 1 billion bytes, and 1 Mbps equals 1 million bits per second. It also accounts for eight bits per byte and 3,600 seconds per hour.
Estimated recording time in hours = Memory card capacity in GB × Available capacity percentage × 8 ÷ (Combined bitrate in Mbps × 360)
Enter the available capacity as a percentage, such as 85 for 85%. The factor of 360 in this form accounts for the percentage conversion, the decimal storage and bitrate units, and the conversion from seconds to hours.
Worked example: Assume you have a 128 GB card, estimate that 85% is available for loop recording, and use a combined recording bitrate of 20 Mbps.
- Memory card capacity: 128 GB
- Capacity available for loop recording: 85%
- Combined recording bitrate: 20 Mbps
- Calculation: 128 × 85 × 8 ÷ (20 × 360)
- Estimated Recording Time: 12.09 hours
In this example, 85% of the card is approximately 108.8 GB of available space. The result assumes the entered percentage already accounts for protected recordings and other files. The inputs are illustrative assumptions, not recommendations for every dash cam.
Use cases for the Dash Cam Loop Recording Calculator
Compare memory card capacities. If you are considering a larger card, enter each capacity while keeping the available percentage and bitrate the same. This gives you a consistent way to estimate how much additional footage each card could retain. Check that your dash cam supports the capacity and card type before choosing one.
Compare single- and dual-camera recording. Adding a rear camera increases the combined bitrate when both cameras record simultaneously. Enter the total for each setup to see how the extra video stream could reduce the time retained on the same card.
Estimate the effect of video settings. Higher-resolution or higher-quality settings may use a higher bitrate. If you know the approximate bitrate for each setting, compare the results to understand the storage trade-off. Resolution alone is not enough to determine an accurate bitrate.
Plan for a long drive. Compare your estimated recording time with the length of a trip to see whether the available loop-recording space may hold the entire journey. Leave room for variation: a result close to your trip length does not guarantee that every minute will remain on the card.
Account for protected footage. If your camera has saved event clips that cannot be overwritten, those files can leave less room for regular loop recordings. Reduce the available percentage to reflect your estimate of the remaining space.
Other factors to consider when calculating Estimated Recording Time
Bitrate can vary. Some cameras use variable bitrate recording, so the amount of data saved per second can change with the scene and recording conditions. A single entered bitrate is an estimate and may not represent every part of a journey.
Include every recording stream. A front and rear camera may use different bitrates. If both record at the same time, add them before entering the combined rate. If your system records additional streams, include those as well when you know their rates.
Audio and file overhead use space. Audio, file structures, and other recording data can affect the amount of footage that fits on a card. If the bitrate you enter does not account for all recorded data, the actual retention time may be shorter than the estimate.
Protected clips and other files reduce available capacity. Event recordings, manually locked clips, and unrelated files may occupy space that normal loop recording cannot use. The available-capacity percentage should reflect the space left after those files and other unavailable space are considered. If the amount of protected footage changes, update your estimate.
Actual usable capacity may differ. The calculator uses decimal GB for its calculation. The available space reported by a camera or computer can differ from the card’s advertised capacity because of formatting, storage overhead, and how devices display units.
Recording behavior depends on the camera. Dash cams can differ in how they divide footage into files, protect events, and manage storage. This calculator estimates retained footage; it does not determine individual clip duration or predict exactly when a particular file will be overwritten.
Dash cam loop recording calculator FAQ
How long will a 128 GB card record in a dash cam?
It depends on the available capacity and combined bitrate. With the illustrative inputs of a 128 GB card, 85% available capacity, and a 20 Mbps combined bitrate, the calculator estimates 12.09 hours. Different settings, protected files, and actual bitrate variation will change the result.
Does loop recording stop when the memory card is full?
Loop recording is designed to continue by overwriting the oldest unprotected footage when the available recording space fills. Camera behavior can vary, especially if protected files occupy a large portion of the card, so check your device’s instructions for its storage behavior.
Should I add the front and rear camera bitrates?
Yes. When both cameras record simultaneously, enter their combined recording bitrate. For example, if the front camera records at an assumed 12 Mbps and the rear at an assumed 8 Mbps, enter 20 Mbps. Use your own camera’s rates when available.
Do protected clips count toward the available percentage?
The percentage entered should represent the space available for loop recording after allowing for protected clips and other files. Because protected clips may not be overwritten during normal loop recording, they can reduce the space available for regular footage.
Is the estimated recording time the length of each video clip?
No. The result estimates the total footage that can fit in the available loop-recording space at the entered combined bitrate. A dash cam may divide that footage into multiple shorter files, depending on its settings and design.