Dash Cam SD Card Recording Time CalculatorHow many hours of video will your memory card hold?

How to use the Dash Cam SD Card Calculator

1. Pick your SD card size. Choose the capacity printed on the card. The calculator already removes the space lost to formatting.
2. Set the number of cameras. A front-only cam is 1 channel, front and rear is 2, and front, rear and cabin (common for rideshare drivers) is 3.
3. Choose the resolution of each camera and the front frame rate. 60 fps files are about 50% bigger than 30 fps files.
4. Enter your camera’s bitrate if you know it. It is often listed in the manual or shown in the file properties. Otherwise the tool uses typical bitrates for each resolution.
5. Tell it how you drive. Daily driving time, the space your camera keeps for locked event files, and parking mode settings decide how many days pass before old footage is overwritten.

How a dash cam fills an SD card

A dash cam records video in short clips, usually 1, 3 or 5 minutes long. Each clip is a separate file, and the size of that file depends almost entirely on one number: the bitrate, measured in megabits per second (Mbps). Resolution, frame rate, compression and the quality setting all feed into the bitrate, which is why two 4K cameras can fill the same card at very different speeds.

When the card is full, loop recording deletes the oldest normal clip and writes a new one in its place. You never have to empty the card by hand, but it also means your footage only exists for a limited window. If you notice a scrape in a parking lot three days later, the clip is only still there if your card holds more than three days of driving.

Clips that the G-sensor locks after a bump, or that you save with the event button, go into a protected folder. Most cameras set aside 10% to 30% of the card for these files, and that space is not available for loop recording. This calculator lets you set that share so the hours it shows match what you will actually get.

Typical dash cam bitrates by resolution

Manufacturers rarely print bitrate on the box, but the figures below are close to what most current cameras use at their default setting. Rear and cabin cameras usually record at a lower bitrate than the front camera, even at the same resolution.

Cameras that use H.265 (HEVC) compression can keep the same picture quality at a lower bitrate than older H.264 models, so a modern 4K cam may use less space than you expect. If your camera has an H.265 option, turning it on is the easiest way to stretch a card, as long as your phone or computer can play the files.

Recording time for common setups

These figures assume standard quality, 30 fps, and 15% of the card reserved for event files. Use the calculator above for your exact camera.

Parking mode and SD card space

Parking mode keeps the camera watching while the car is off, which can add many hours of footage a day. How much space it takes depends on the mode:

• Time-lapse: records 1 or 2 frames per second and plays them back fast. An hour of parking takes only a few percent of the space of an hour of driving, so it is the most storage-friendly option.
• Low-bitrate recording: records normally but at a reduced bitrate. It uses roughly a third of the space of normal driving footage.
• Motion or impact detection: only saves a clip when something happens. Storage use is low, but the camera may miss the start of an event.

Parking mode also draws power from the car battery through a hardwire kit. Set the kit’s cutoff voltage so the camera shuts down before the battery gets too low to start the engine, especially in cold weather.

How to choose the right SD card size

Think in days, not hours. The question to ask is: if something happens, how long will I have to save the clip before it is overwritten? For most people, a card that holds at least 3 to 5 days of normal driving is a sensible target. That gives you time to notice a ding or deal with an insurance claim.

• Short commutes with a 1080p cam: 64 GB is usually enough.
• 2K or 4K front cameras: 128 GB is a good starting point.
• Front and rear 4K, 3-channel cams, or long daily drives: 256 GB or more.
• Parking mode for many hours a day: add one size, unless you use time-lapse.

Always check the maximum card size your camera supports before you buy. Many cameras top out at 128 GB or 256 GB, and a card above the limit may not work at all.

Use a high endurance card

Dash cams write to the card constantly, which wears out ordinary cards in months. High endurance or max endurance cards are built for continuous recording and are rated for thousands of hours. Look for a card rated U3 or V30 for 4K recording, so it can keep up with the bitrate without dropping frames.

Format the card regularly

Formatting the card in the camera every few weeks clears fragmented files and reduces the chance of corrupted clips. Many cameras can remind you or do this automatically. Copy any clips you want to keep first.

The formula behind it

The 0.93 factor accounts for the difference between how card makers count gigabytes (1,000,000,000 bytes) and how cameras and computers count them, plus file system overhead. Typical bitrates are 45, 20, 12 and 6 Mbps for 4K, 2K, 1080p and 720p front cameras at 30 fps. Rear and cabin channels use about 80% of those figures, 60 fps adds 50%, and each channel’s audio adds a small amount.

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