After making the appropriate entries for either takeoff or landing performance and selecting Calculate, one of the results in the area at the bottom is "Margin", a number with units in meters.

What does this number represent?

 

Thanks

i believe it is how much runway is expected to be leftover when you lift off. for example i calculate for LROP a takeoff on 8R which is 3500m it shows a 2335 margin meaning my takeoff run should be around 1165m

i don't know the exact definition but i think it's something like that!

cheers,-andy crosby

That’s correct. It’s the amount of runway remaining at the point that the main wheels leave the ground. Andy beat me to it.