Work out overtaking distance instantly with clear inputs, formula shown and shareable results.
Overtaking time is the gap to close divided by the speed difference, and the clear road needed is your travel plus an oncoming vehicle's travel over that time. A 25 km/h speed advantage needs about eight seconds and over 400 m of clear road.
Overtaking sight distance
time = (vehicle lengths + safety gap) / relative speed; clear distance = (your speed + oncoming speed) x time
Because you and any oncoming vehicle close at the sum of your speeds. At 100 and 90 km/h that is 190 km/h, or 53 m every second.
The overtake takes proportionally longer and becomes very dangerous. Below about 15 km/h difference on a two-lane road it is rarely worth attempting.