The inrun-speed is measured approx. 10 meters before the edge of the take-off table.
On jumping hills up to 95 km/h and on flying hills up to 105 km/h are reached. The athletes wants to gain as much speed as possible in the inrun. The speed is effected by the position of the athlete during the inrun and the preparation of the skis. Also the bodyweight of an athlete influences the speed.
The general rule applies that a higher speed results in a longer jump. But some athletes can make up for less speed compared to the competition for example with a very good take-off.