Turning average speed into lap and race time
How average lap speed becomes a lap time and a full race time, why it differs from top speed, and how to handle miles and kilometres.
The formula behind a lap time
A lap is just a distance, so its time is distance divided by speed. Working in miles and miles per hour, the raw answer is in hours, so multiplying by 3600 converts it to seconds: lap seconds equals miles divided by mph, times 3600. A 2.5 mile lap at a 120 mph average therefore takes 2.5 / 120 x 3600 = 75 seconds, which the tool shows as 1:15.000. The same relationship works in reverse, which is why entering a known lap time lets you skip the distance and speed entirely.
Average speed is not top speed
The speed this tool wants is the average over an entire lap, not the peak seen on the straights. A lap is a mix of full-throttle sections, braking zones and slow corners, so the average is dragged well below the top speed. On many circuits a car touching 180 mph on the straight may average only 110 to 130 mph across the lap. Feeding in a top speed would produce a lap time that no car could actually achieve, so use a realistic average from telemetry or a previous session.
Miles, kilometres and the conversion
Track lengths are quoted in kilometres in most of the world and in miles at many oval and North American circuits, so the length box accepts either unit. When you pick km, the value is converted to miles by dividing by 1.609344 before the formula runs, which is why a 3 km lap at a 100 mph average comes out as 1:07.108. One thing to watch is that the speed field stays in mph even when the length is in kilometres, so convert a km/h figure to mph first if that is what you have.
Scaling one lap to a full race
Once you have a representative lap time, the total race time is simply that lap multiplied by the number of laps, which is what the Laps field does. This gives a quick baseline for a stint or a full distance: fifty 75-second laps add up to 3750 seconds, shown as 1:02:30. The number is deliberately optimistic because it assumes every lap matches the average, with no pit stops, safety cars or tyre fall-off. Treat it as the floor of a race time and add your own allowances for stops and traffic on top.