What is the best measure of a Compact Flash card's transfer rate?

Question

What is the best measure of a Compact Flash card's transfer rate?

Answer 1

I usually do a sustained read and write test of a fairly large file. Generally, the write speed will be slower than read.

There are programs that will allow you to do read and write speed tests.

You can also do this by creating a file around 50 MB and transferring the file from your computer to the CF card (write test). Time the transfer and calculate the number of megabytes per second. Fast cards will do over 20MB/s. Slower cards will do under 10MB/s. For a read test, copy the file you saved on the CF card and transfer it back to your computer. You may need to reboot your computer to clear out the cache (you'll get silly transfer rates if the data is cached).

Be sure that you use a card reader which plugs into your computer. Testing the card's data rate through a camera is testing the camera's transfer rate limitations which is usually much slower than the card's.