SD Card Recording Time Calculator
Use the SD Card Recording Time Calculator to estimate how many hours of dash cam footage can fit on a memory card before its available recording space fills. Enter the card’s capacity, the combined video and audio bitrates, and the percentage of the card available for recordings. The result is an estimate in hours based on a constant average bitrate.
Whether you use a single front-facing dash cam or a system with several cameras, this estimate can help you compare storage options and understand how long footage may remain available when loop recording is enabled. Actual recording time will vary with your camera’s settings, compression, file overhead, and recording behavior.
What the SD Card Recording Time Calculator does
The calculator converts your SD card’s capacity into an amount of recording data and divides it by the rate at which your camera produces video and audio. It then displays the Estimated Recording Time in hours, rounded to two decimal places.
For example, the illustrative default settings use a 128 GB card, a combined video bitrate of 16 Mbps, no audio, and 90% of the card’s capacity available for recordings. These inputs produce an estimated 16.00 hours of footage.
This is an estimate of how much footage can fit in the available space, not a guarantee that a particular clip will remain on the card for that long. With loop recording, the camera typically overwrites older footage when the available space fills. Protected event clips and other files can also affect the space available for ordinary recordings.
How to use the SD Card Recording Time Calculator
Enter the following four values to calculate an estimate for your dash cam setup:
- SD card capacity (GB): Enter the advertised capacity of your card in gigabytes. The calculator uses decimal GB, where 1 GB equals 1 billion bytes. It accepts values from 1 to 2,000 GB.
- Combined video bitrate (Mbps): Enter the total video bitrate in megabits per second. For a multi-camera system, add the video bitrates for all channels that record to the card. The accepted range is 1 to 200 Mbps.
- Combined audio bitrate (Mbps): Enter the total audio bitrate in megabits per second for all recorded channels. Enter 0 if audio is not recorded. The accepted range is 0 to 10 Mbps.
- Capacity available for recordings (%): Enter the percentage of the card you expect to be available for the footage included in your estimate. This allowance can account for reserved space and file overhead. You can enter a value from 1% to 100%.
The calculator displays the estimated recording time in hours. If you do not know your camera’s bitrate or available storage percentage, use reasonable assumptions and treat the answer as a planning estimate. The default values are illustrative and do not represent every dash cam.
For the most useful result, check the specifications or settings for your camera’s chosen resolution, frame rate, compression format, and recording mode. If the manufacturer lists separate bitrates for the front and rear cameras, add those figures before entering the combined video bitrate.
How the SD Card Recording Time Calculator formula works
The calculation starts by converting the card’s decimal capacity from gigabytes to megabits. One decimal gigabyte contains 8,000 megabits. The calculator then applies the usable percentage, divides by the combined video and audio bitrate to find the number of seconds, and converts those seconds into hours.
Formula: Recording time in hours = SD card capacity in GB × 8,000 × available capacity percentage ÷ 100 ÷ (combined video bitrate + combined audio bitrate) ÷ 3,600.
The bitrate inputs use Mbps, or megabits per second. This is different from megabytes per second, so check the units before entering a figure from a camera specification. Video and audio rates are added because both types of data occupy storage space.
Worked example: 128 GB SD card
Suppose your dash cam uses the calculator’s illustrative default settings:
- SD card capacity: 128 GB
- Combined video bitrate: 16 Mbps
- Combined audio bitrate: 0 Mbps
- Capacity available for recordings: 90%
First, 128 GB × 8,000 equals 1,024,000 megabits. Applying the 90% availability assumption gives 921,600 megabits. Dividing by the combined bitrate of 16 Mbps gives 57,600 seconds. Finally, dividing by 3,600 gives an Estimated Recording Time of 16.00 hours.
The 90% figure is an assumption for this example. Your card and camera may leave a different proportion available for recordings, and the actual average bitrate may differ from the value entered.
Use cases for the SD Card Recording Time Calculator
Compare SD card capacities. If you are deciding between compatible cards, calculate each capacity using the same bitrate and usable percentage. Under the calculator’s constant-bitrate assumptions, doubling the available capacity doubles the estimated recording time.
Plan for front and rear cameras. A dual-channel system records more video data than a single channel when both are active. Add the front and rear video bitrates, along with any recorded audio bitrates, to estimate the total storage demand.
Compare recording settings. A higher resolution or frame rate can require a higher bitrate, although the actual rate depends on the camera and compression settings. If your camera provides bitrate figures for different modes, enter each one to see how the estimated storage time changes.
Estimate a loop-recording window. The result can help you understand approximately how much continuous footage fits before ordinary loop recordings begin to overwrite older files. Save any footage you need promptly, since the calculator cannot predict exactly when a particular clip will be overwritten.
Account for audio. Audio also uses storage when enabled. Including its bitrate gives a more complete estimate; entering zero represents recording without audio.
Other factors to consider when calculating Estimated Recording Time
Variable bitrate: Many cameras adjust the amount of data they use as a scene changes. Motion, lighting, weather, and image detail can affect the actual rate. The calculator assumes the entered rates remain constant averages, so a changing bitrate can make the real recording time longer or shorter.
File overhead and reserved space: Formatting, file structures, and camera-reserved storage can reduce the space available for footage. The capacity available for recordings percentage lets you account for these factors, but it remains an estimate unless you know how your camera allocates the card.
Protected clips and other files: Dash cams may save impact or manually protected clips separately from normal loop footage. If those files share the card, they can leave less space for ordinary recordings. Choose an available capacity percentage that reflects the space you expect to use for the footage you are estimating.
Recording mode: Continuous driving footage, parking mode, time-lapse recording, and event-triggered recording may use different settings or record for different portions of the day. A single bitrate estimate is most useful when the recording mode and its average data rate are reasonably consistent.
Camera and card compatibility: Storage capacity alone does not establish whether a card will work with a dash cam. Check the camera manufacturer’s supported capacities and card requirements before choosing one. The calculator estimates time; it does not check compatibility or card condition.
SD Card Recording Time Calculator FAQ
How long will a 128 GB SD card record in a dash cam?
It depends on the combined bitrate and the space available for recordings. With the illustrative assumptions of 16 Mbps video, no audio, and 90% usable capacity, the calculator estimates 16.00 hours. Different camera settings and storage usage will change the result.
How do I calculate recording time for a front and rear dash cam?
Add the video bitrates for both cameras and enter the total as the combined video bitrate. Add any recorded audio bitrates and enter that total separately. Use the card capacity and the estimated percentage available for recordings to complete the calculation.
Does a higher bitrate reduce SD card recording time?
Yes. If capacity and the available percentage stay the same, a higher combined bitrate uses storage faster and reduces the estimated recording time. For example, doubling the combined bitrate halves the estimate under the constant-bitrate assumption.
What percentage of my SD card is available for recordings?
There is no single percentage that applies to every card and camera. Formatting, reserved space, protected clips, and other files can affect what remains available. The calculator’s 90% default is an illustrative assumption; adjust it if you have better information about your setup.
Does the calculator show when old dash cam footage will be deleted?
It estimates how much footage fits in the available space at the entered average bitrate. With loop recording, older footage is typically overwritten once that space fills, but protected files, event recordings, variable bitrates, and camera settings can change the timing.