The Nm is newton meters I believe. iIt is a measure of force over distance or torque. I belive that is what you want based on post being in the DIY router section.
the conversion would be as follows
1Nm = .7376 ft lbf
lbf = pound force
1 ft lbf = 12in/ft x 16 oz/ lbf
thus
1 Nm=141.6192 in oz
I would check again to make sure it is Nm and not N/m. N/m would convert to 1N = 1Kg/m(s^2)/m. This would lead towards a mass/area x time. This seems unlikely to be auseful measurment for anything other than maybe a bearing.
For future referece, you could do a google search and download a converter.