from what i remember density goes from .76 to .84 depending on temperature, refinery and fueltype (Russia has some pretty exotic ones) the supplier should give you the dnsity of his fuel and you can compute the uplift with that...... now i dont know what differences in gauged and actual are tolerable, let me inform you though that i know of cases where the difference was 2000 LBS on a 180000lbs uplift. Time and again and again.