Lap times are minutes and seconds with a decimal tail, so they have to be converted to seconds before anything can be done with them. The five laps 1:32.40, 1:31.85, 1:33.10, 1:31.20, 1:32.75 average 1:32.26, computed as 461.30 seconds divided by 5.
Consistency is often more revealing than the fastest lap. The spread here is 1.90 seconds between best and worst, and a driver or runner whose laps sit within a few tenths of each other is usually quicker over a full distance than one with a stunning single lap and a wide scatter.
The projection multiplies the mean lap by a distance you set, which is the honest way to estimate a finishing time from a practice set. It assumes the pace holds, so it is a benchmark rather than a prediction — but it makes the cost of a slow lap immediately visible.
The formula
n- Number of laps
x̄- Mean lap in seconds
Δ- Spread from fastest to slowest
L- Race distance in laps for the projection
How it works, step by step
- Enter the lap times separated by commas, as M:SS.hh.
- Plain seconds such as 92.4 are accepted too.
- Enter the full race distance in laps for the projection.
- Read the mean lap, the spread and the projected total.
Worked examples
Five laps averaged
Converted to seconds the laps are 92.40, 91.85, 93.10, 91.20, 92.75, totalling 461.30 s. Divided by 5 that is 92.260 s, or 1:32.26, with a spread of 1.90 s between the best and worst lap.
What a slow lap costs over a race
At the mean of 1:32.26, twenty laps project to 1845.2 seconds — 0h 31m. Running instead at the fastest lap of 1:31.20 would save 21.2 seconds over the same distance.
How to read your score
Frequently asked questions
What format should lap times use?
M:SS.hh, such as 1:32.40, or plain seconds such as 92.4. Both can appear in the same list, and seconds values of 60 or more in the M:SS form are rejected as invalid rather than silently accepted.
Why show standard deviation rather than just the range?
The range only reflects two laps. The standard deviation uses every lap, so one anomalous out-lap does not define the whole picture. Under half a second is generally considered tight.
Is the projection a realistic finishing time?
It is a benchmark, not a prediction. It assumes the mean pace holds for the full distance and ignores fuel load, tyre wear, traffic and pit stops, all of which move the real figure.
Should I include an out-lap in the average?
Usually not. An out-lap is several seconds slower and will drag the mean, which is why the fastest and slowest laps are shown separately so you can spot one that does not belong.
Lap timing reference
| Lap times | Mean lap | Spread | 20-lap projection |
|---|---|---|---|
| 1:32.40, 1:31.85, 1:33.10, 1:31.20, 1:32.75 | 1:32.26 | 1.90 s | 0h 31m |
| 0:58.20, 0:57.90, 0:58.55 | 0:58.22 | 0.65 s | 0h 19m |
| 2:04.10, 2:06.30, 2:03.80, 2:05.00 | 2:04.80 | 2.50 s | 0h 42m |
| 1:45.00, 1:52.40, 1:44.60 | 1:47.33 | 7.80 s | 0h 36m |
Means are computed in seconds and converted back; the projection assumes the pace holds.