What is the length of the outside of a 400M track in meters?

Answer 1

or if you want to know the distance of each lane i think lane 8 is something like 450m. if you measure from the start of the 400m back to the finish line and add 400m that should give the dist. you would travel in that lane

Answer 2

If you can trust the person who told you it's a 400 meter track,

then no calculation is necessary. The length is 400 meters.