While choosing a memory card, there are two main things that you should keep in mind. Firstly, the type of memory card you want and secondly, what size of memory card you should buy?
Memory cards are not useful for only storing pictures, they are also useful for storing videos. So not only do you need to know the picture capacity your SD card has, but you also need to know how much video capacity it has.
This article covers all the factors that affect video file size and a little bit about memory card calculators to make it easier for you to purchase the right storage space so that you never run into trouble running out of space right in the middle of an interesting video.
- If you have an SD card whose storage space is 64 GB, it can hold up to 21 minutes of 4k video at 24 fps and 17 minutes at 30 fps.
- At the recording speed of 200 Mbps, a 64 gb sd card can hold up to 40 minutes of 4k video. At the speed of 150 Mbps, it can hold up to 55 minutes of 4k video.
- At the recording speed of 100 Mbps, it can hold up to approximately 1 hour 20 minutes of 4k video.
What capacity memory card do you need?
Every digital camera uses memory cards to store your videos. Choosing the right one is important.
Memory cards come in various shapes and sizes and different cameras use different sd cards. Hence, the first step is to know what type of sd cards are compatible with your digital camera.
A point worth noting is that there are many high-end cameras that support multiple cards. In situations like these, you will want to choose an sd card with a faster write speed.
For all the serious videographers, SD or SDHC have a low capacity for today’s minimum video standards. So SDXC cards are an ideal option if you do not want your videos to split into 4 gb chunks.
Once you know what type of sd card is right for your needs, the next step is to think about the kind of videos you want to shoot, as different types of videos will have different demands for speed and capacity.
Write speed should be the first concern whenever choosing a memory card, as it determines how fast data can be saved on the memory card. This is especially critical when dealing with the highest quality videos.
If the memory card is too slow and unable to handle the incoming data during recording, it will start dropping frames or may store the video in a lower than expected quality.
While recording videos, it is imperial to remember that you will be writing data continuously on the card. So your sd card must be reliable and capable of sustaining a certain minimum write speed.
For shooting full HD video or 4k videos with lower bitrates and lower frame rates, a V30 memory card might be enough space.
If you are shooting 4k videos at higher bit rates and higher frame rates, you will need a faster card, such as the V60.
Another thing you need to take care of while choosing your memory card is the read speed.
Read speed determines how quickly you can retrieve recorded videos from the memory card.
It does not affect the video quality nor does it hinder your camera’s performance, but it does affect the workflow.
A faster read speed decreases your wait time by allowing you to transfer the data from the card to your computer faster, which in turn will allow you to get to editing and sharing your work a lot quicker.
You will need a faster read speed for projects with short deadlines that require quick turnovers!
What affects video file size?
To know how much 4k video can 64gb hold, you first need to get acquainted with the factors that affect video file size.
Frame rate is the speed at which distant still images are shown as a video file. So if a video is captured and played back at 24 fps, that means each second of that video shows 24 distant still images.
Different frame rates yield different viewing experiences, such as how realistic you want your video to look or if you want to use slow motion or motion-blur effects.
The higher the frame rate the more frames per second are used to display the sequence of images, resulting in smoother motion. Hence, higher frame rates require a large amount of storage.
24 fps and 30 fps are most commonly used in theatres or on television. If the frame rate doubles, the file size of the video will also double depending on the compression.
So if you are looking forward to shooting at a high frame rate, then you might want to look into a higher capacity memory card.
Your camera can capture a dynamic range of colour images in a variety of different colour containers called “space”.
These camera colour spaces collect colours in one of several size light buckets labelled as sRGB, AdobeRGB and RAW.
The camera colour spaces involve not just the colour data, but additional storage space on your sd card.
Some professional video cameras shoot in log profiles. In log picture profiles more information is saved for later editing, allowing you the main control over the final colours and contrast.
This is mainly used for pro-level videos and hobbyists, rather than for normal home use.
You can even convert the file’s original space colour if you want a less demanding result.
However, it is essential to keep in mind that every time a file mutates from a larger colour space to a smaller colour space, the image quality, intensity and integrity diminishes in the process.
For the ones who love to make simple home videos, you can choose to shoot a video through the standard mode in your camera, which will result in much smaller files.
JPEG and RAW formats are the two most common types of camera type storage formats.
Between JPEG and RAW file types, RAW stores more colour and tonal value data, which gives you the flexibility of editing the photo later.
The file formats that are commonly used for videos are DV, HDV, MPEG-2, AVCHD, H.264, MPEG4, etc.
H.264 is one of the popular formats that is used not only by high-end camcorders but also by pocket-size devices.
This format is capable of supporting HD video and a standard recording video. This format allows you to record a high-quality video that can be compressed so that too much memory or space is not occupied.
A video recorded using the H.264 codec will be double the size of an equivalent length/frame rate video recorded using the HEVC codec.
Compression is a function of how much information is kept or discarded to make the photo or video file smaller when storing it.
Many formats use compression to reduce the file size by selectively reducing video quality. However, you do have more control over the compression used.
The more compression, the smaller the size.
In some cases, such as movies, compression is essential for reducing the size of the video so that they can be stored, transmitted and played back effectively.
Different digital cameras use different terms for compression. Some use size terms such as large, medium and small to describe the file format resulting from compression.
The common options for compression are:
- All-I – Of all of these choices, All I is the heaviest and takes up a lot of space in the memory card because, in this option, every frame is recorded to your card.
- Intra-frame & Inter-frame – Both of these options choose compression methods where the frames in the recording mode get skipped and compiling similar frames into one, reducing the size.With these methods, the resulting file is much smaller and this means that you can store more hours of video per GB of storage.
A bit rate also known as the data rate, affects the video quality of a clip. It refers to the number of video bits transferred within a second.
When you have a larger bit rate, it means that a larger amount of video bitrate is being uploaded within a second. This naturally leads to higher video quality.
Increasing the bit rate will increase the size of your output video file and result in a relatively slower export and lower bit rate results in lower video quality, smaller size and faster export.
The bit rate also defined as Megabits per second gets transferred from the camera to your memory card and is available in your camera manual.
Video bitrate is usually measured in megabits per second (Mbps), so it tells you exactly how many bits are written to the memory card each second.
Knowing how many bits are written makes calculating the video file sizes pretty straightforward. Just multiply the bitrate with the duration of the video, and you’re done.
The formula for calculating video file sizes is Video File Size = Bitrate (Mbps) / 8 (bits) x Duration (seconds).
Memory card calculator
The memory card calculator provides an easy way to calculate the following:
- The required memory size.
- Data logging.
Despite all the different codecs and picture quality settings, calculating video file sizes is a quick and easy process.
Calculate the capacity of any SD memory card or Micro SD memory card with the memory card calculator link given below.
The answer to your question, how much 4k video can 64 gb hold depends more on your camera than the sd card capacity.
Different camera models can store a different amount of minutes of video on the same size sd cards.
For example, the Sony A7III can store 1 hour 25 minutes of 4K video on 64 GB, while the Canon 5D Mk IV can only store 17 minutes of 4K on the same sized card.
Even though the storage capacity of 4k video depends on your camera, it also depends on your sd card.
When you are recording 4k videos, you need an sd card that can support high transfer rates, or else your video will get cut short is and when your camera buffer is full.