Fuel Density
As well as knowing flight planned fuel I have always determined two things before uplift. (a) no contamination in the fuel to be uplifted and, (b) density of the fuel to be uplifted. Knowing density of fuel to be uplifted and fuel remaining before uplift it is simple to calculate the amount of fuel to be uplifted. I have had to uplift fuel in US Gallons, Imp Gallons and litres worldwide, the one common value always determined before uplift being uplift fuel density. Always, fuel loading was in either lbs or Kgs depending on aircraft type. Fuel flight plan always used fuel required in either lbs or Kgs. At least two individual methods of determining fuel on board had to be used and a maximum difference allowed between fuel by uplift vs fuel by gauge was 3% with the lesser amount being considered fuel on board. Outside the 3% differential the reason had to be determined. If known fuel on board before uplift and amount uplifted equals desired fuel load at the completion of refuelling, no problems. As I previously said, fuel distribution for any aircraft I have operated as a F/E has been determined by weight of fuel, not volume.