ND Grad numbers question

[BigLoada]

I am looking into getting some ND grads but I was wondering what the numbers relate to. Such as 0.3, 0.6 etc etc. Do these relate to the amount of filtering, such as a third or two-thirds of a stop etc? I am trying to work out what ones to get for landscape photography.

Thanks for any info

 

[puddleduck]

0.3 = 1 stop
0.6 = 2 stops
0.9 = 3 stops

If getting just one, go for a 0.6 / 2 stop soft grad.

 

[BigLoada]

Thanks Puddleduck, thats exactly the info I needed, cheers

 

[whiteflyer]

All explained here