%grade= vertical lift/run*100
in the above case:
avg. vertical lift is about 320
avg. run is about 4.6 miles (24,288 ft) actually it is slightly less but the difference will not change the %grade significantly
% grade = 320/24288*100 = about 1.3%
I tried the ped site, but no maps available for my area (too bad).
I have looked into some altimeter watches, however I'm not sure if knowing my exact altitude gain is that important to me.