What Are Memory Card Read & Write Speeds?
It all sounds very technical. Read and Write Speeds? Do I need a fast read and write speed? What do they mean? What does read speed mean? What does write speed mean? Well, below we will try and explain if you’re in the dark on these phrases.
What does Write Speed mean?
Write speeds are generally the most important feature of a memory card. Write speeds determine the amount of time it takes to transfer the data, the moment you for example, click the button on your camera to ask the camera to take the image. You will probably remember that back in the early days of SD memory cards, there was an awful amount of lag time on cards, i.e from when you heard the click on the button (when you asked your camera to take the picture), to when you heard the double click (which is normally when the image has been written to the card).
What does Read Speed Mean?
Read speeds indicate the amount of time it takes for a card to transfer the data to a PC/Laptop. I.e the amount of time it takes to read the data off the card. Generally the higher the capacity of the card, this will naturally give a higher write speed. So a 4GB card will offer lower read speeds than a 32GB memory card. Read speeds are particularly important on higher capacity cards as if you have a 32GB full up with data and the read speed is poor/low then you will wait much longer to transfer the data from the card. A Pretec P240 USB 3.0 Memory Card Reader Writer will drastically reduce wait times for transferring data. Up to 5Gb/s! Thats up to 10x faster than the traditIonal USB 2.0!
If I see 45MB/s What Does This Mean?
If buyers are particular about what they need in respect of fast read or fast write speeds then you need to make sure that you are aware of this number quoted on the card. More often than not, this will be the read speed quoted, and not the write speed. This is a bit cheeky of the manufacturers really, as most specific users that look into this figure, require high value write speeds, and instantly you assume the number quoted on the card is the write speed, but it is infact usually the read speed, as the read speed is always a higher number than the write speed.
What impact do Write Speeds have on HD devices?
Generally a class 10 card and above is recommended for HD movies/video capture. Again this boils down to the write speed, and the amount of time it takes to write the data to the card. There will be a more seamless writing efficiency, with a class 10 card for HD video. i.e no interuptions in the recording smoothness. You may find your device will encounter issues with anything below a Class 6 SDHC memory card.
If I See Something Like 133x, What Does This Mean?
This is just another way of showing a read or write speed. Below is a list of how to convert a figure with an ‘x’ on the end into the more industry standard MB/s.
8X = 1.2 Mb/sec
12X = 1.8 Mb/sec
20X = 3.0 Mb/sec
25X = 3.8 Mb/sec
30X = 4.5 Mb/sec
40X = 6.0 Mb/sec
60X = 9.0 Mb/sec
66X = 10.0 Mb/sec
80X = 12.0 Mb/sec
90X = 15.0 Mb/sec
133X = 20.0 Mb/sec
What Memory Card Is Suitable For My Device?
This really depends on two things, your budget, although flash memory is very affordable now, and what you need your memory card for.
If you simply require your memory card for a simple compact point and shoot digital camera, then anything around the Class 4 product range will be perfect. E.g the Kingston Class 4 SDHC Memory Card.
If you have a compact digital camera that will shoot HD video, then any brand of memory card that’s class 10 rated will be more than suitable.
If you have a more precise camera such as a digital SLR camera then something along the lines of the new UHS SDHC memory cards would probably be more suitable for your needs.
