This is the formula for calculating the peak FLOPS on your cuda enabled gpu. (as uses by NVIDIA) This is useful as a comparison when evaluating how many FLOPS your cuda kernel is achieving, and how much you can hope to gain through optimization. You can get the numbers needed from the NVIDIA control panel’s system information option.
If your card is pre-fermi:
Processor clock*cuda cores*3
If your card is fermi based: (or higher?)
Processor clock*cuda cores*2
Original Source here.