A 10.85 with a +3.1 tailwind and a 10.98 into a -1.2 headwind aren't the same run, and the results sheet can't tell you which was better. Watch the same sprinter race in four different winds, then convert any result to its still-air, sea-level value.
What the research says about wind
Wind is printed next to every 100 m, 200 m, sprint hurdles, long jump and triple jump result for a reason. The limit for records is +2.0 m/s, but a legal +2.0 still helps: across thousands of results, it was worth about 0.125 s over 100 m, 0.140 s over 200 m and 0.146 s in the sprint hurdles (Moinat, Fabius and Emanuel, 2018). Athletes running around 13 seconds gained about 69% more than athletes running around 10 seconds.
The physics explains why. A sprinter pushes air out of the way with every stride, and drag rises with the square of their speed relative to the air. Mureika's model puts the share of a sprinter's effort spent against still air at about 2.7%. Ward-Smith's energy model showed the wind works through drag and the energy the athlete wastes, while changes in body lean make little difference.
Altitude does the same job by thinning the air. Usain Bolt's 9.58 world record in Berlin in 2009 came with a +0.9 tailwind at low altitude, worth about 9.62 in still air. Bob Beamon's 8.90 m long jump at the 1968 Mexico City Olympics had a +2.0 tailwind at 2250 m. Ward-Smith calculated the two together added about 31 cm, mostly through a faster approach. At the same Games, 100 m runners were 0.19 s (men) and 0.21 s (women) faster than at low-altitude Olympics (Linthorne, 2016).
Wind isn't always a gift. Over 400 m, Quinn's 2004 model found a steady 2 m/s wind is generally a disadvantage, depending on its direction, and a tailwind down the back straight increases lane 8's advantage over lane 1. The tools below cover the 100 m, where the research is strongest.
True or false?
Test what you think you know before you start. Tap an answer to see what the research says.
A legal wind of +2.0 or less doesn't really help.
A +2.0 tailwind is legal and still worth about 0.125 s over 100 m on average, more for slower athletes.
A headwind costs more time than the same tailwind gives back.
Drag depends on the square of air speed. At 10 m/s, a +2.0 tailwind drops drag to 64% of still air, while a -2.0 headwind raises it to 144%.
A tailwind always helps in the 400 m.
Modelling shows a steady 2 m/s wind is generally a disadvantage over a full lap, depending on direction (Quinn, 2004).
Altitude can matter as much as wind.
About 1000 m of altitude gives roughly the same 100 m advantage as a +2.0 tailwind (Linthorne, 2016).
Race the wind
One sprinter, four lanes, four winds. Set how fast they run in still air and what each lane gets.
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How the race is modelled
Each lane uses the standard shape of a sprint: speed rises towards top speed as v = top speed × (1 − e−t / 1.1). With a time constant of 1.1 s, a sprinter is at 90% of top speed about 2.5 s into the race.
For each lane, top speed is set so the athlete finishes at the time the wind model predicts. Reaction time isn't included, so the clock starts at movement.
Why the gaps look so small
A 0.1 s gap at the finish is about a metre for a 10 m/s sprinter. The difference between a -2.0 headwind and a +2.0 tailwind for an 11-second runner is about a quarter of a second, or 2.5 m. In a close final, that's the difference between first and fourth.
What the animation can't show
Real wind isn't steady. Gusts come and go, and the gauge reports an average. Two athletes in the same race can feel different conditions, and the gauge sits on one side of the track only.
Converter
Enter a 100 m time, the wind reading and the venue. You get the still-air, sea-level equivalent, and a chart of what every other wind would have done for this athlete.
What every wind would have done
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Why wind matters at all
A sprinter pushes air out of the way with every stride. Mureika's model puts the share of effort spent against the air at about 2.7% for a sprinter in still air at sea level.
Drag depends on the square of the athlete's speed relative to the air. At 10 m/s with a +2.0 tailwind, the athlete runs through air at 8 m/s, so drag falls to 64% of its still-air value. Into a -2.0 headwind, air speed is 12 m/s and drag rises to 144%. That's why a headwind costs more than the same tailwind gives back.
Why altitude helps
Drag also scales with air density, which drops by about 1.2% for every 100 m of altitude. Canberra's air is about 7% thinner than at sea level, 1000 m about 12%, and Mexico City about 24%.
At the 1968 Olympics in Mexico City, 100 m times were about 0.19 s faster for men and 0.21 s for women than at low-altitude Games, once wind was taken out. Linthorne estimated that every 1000 m of altitude is worth about the same as a +2.0 tailwind. The converter uses his measured figure, scaled by air density, rather than a physics model alone, which predicts a smaller effect.
Using converted times in coaching
Set training targets and race plans from legal or converted times, not from windy marks. A converted time is also the fairest way to compare juniors who raced in different conditions.
For selection, a converted time is supporting information, not a replacement for the official result. Selection criteria normally refer to legal marks.
Season tracker
Add an athlete's 100 m results for the season. The tracker converts each one, ranks them in still air and shows whether they're actually getting faster. It's saved on this device only.
| Meet | Time | Wind | Altitude | Still air | Remove |
|---|
In order of the season
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How the trend is worked out
The tracker fits a straight line through the still-air times in race order and reports its slope, in seconds per race. With six races, one bad day can swing it, so treat it as a rough guide.
What normal variation looks like
Even in good conditions, a sprinter's times vary from race to race with sleep, rounds, the gun and the competition. A converted improvement of 0.02 or 0.03 s per race is real progress only if it holds across several meets.
Getting the most out of it
Enter every race, not just good ones, and include heats. Note the venue altitude for Canberra or any overseas meet at altitude. The data stays on your device, so use the same browser each time.
Where the gauge reads
The gauge reads the wind along the straight, for a fixed window of time. Pick an event to see where it sits and what part of the race it covers.
A tailwind above +2.0 m/s means the mark can't be ratified as a record or used for most qualifying standards. The athlete still keeps the place and the result.
Readings round up to the next tenth in the positive direction, so +2.01 is printed as +2.1 and is wind-assisted.
The gauge sits within 2 m of the track at 1.22 m high, on one side only. Wind swirls, so lanes 1 and 8 can run in different conditions.
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The reading is an average
The figure on the results sheet is the average wind along the straight over the measuring window. A gust in the last 30 m and a lull at the start can average out to a legal reading.
Why the windows differ
The 10-second window covers the whole of most 100 m races. Hurdles get 13 seconds because the race is longer. In the 200 m the window starts when the first athlete enters the straight, so the bend, which can have its own wind, isn't measured.
Jumps
For the long and triple jump, only the last 5 seconds of the run-up are measured, from a mark 40 m (long jump) or 35 m (triple jump) from the board. A strong tailwind can carry a jumper onto the board faster than their check marks expect, so re-check marks in the warm-up.
Who gains most
Slower athletes spend longer in the wind, so the same breeze is worth more to them. Drag the slider to see what +2.0 is worth at each level.
Across thousands of results, a +2.0 tailwind was worth 0.125 s over 100 m, 0.140 s over 200 m and 0.146 s in the sprint hurdles, 5.8 cm in the long jump and 10.2 cm in the triple jump. Athletes running around 13 seconds gained about 69% more than athletes around 10 seconds (Moinat and colleagues, 2018).
At the 1968 Olympics in Mexico City (2250 m), 100 m runners were about 0.19 s faster for men and 0.21 s for women than at low-altitude Games, once wind was allowed for. Every 1000 m of altitude is worth roughly the same as a +2.0 tailwind (Linthorne, 2016).
Modelling the energy a sprinter spends against the air shows the wind's effect works through drag and how much energy the athlete wastes, while changes in body lean make little difference (Ward-Smith, 1999).
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Why slower sprinters gain more
Two things add up. A slower athlete spends longer in the wind, and the same wind is a bigger share of their speed. A +2.0 tailwind cuts drag to 54% for someone running 7.5 m/s, compared with 64% for someone running 10 m/s.
What it means for juniors
A junior running 13 to 14 seconds gains about 0.16 to 0.18 s from a +2.0 tailwind, and close to 0.3 s from +4.0. Comparing juniors across meets without allowing for wind can mislead selection and goal-setting.
Limits of the research
The results-data figures are averages across many athletes, and the physics models assume a typical body shape. Taller, more upright sprinters present more area to the wind.
Notes and references
Compare runs in still air, not on the results sheet.
A windy PB is a good sign, not a new baseline.
Set training targets from legal or converted times.
How the tools work
Wind uses Mureika's correction for the 100 m: still-air time = time × [1.027 − 0.027 × (1 − wind × time ÷ 100)²]. Altitude uses Linthorne's measured advantage at Mexico City (about 1.9% of race time at 2250 m), scaled by how much thinner the air is at the venue. The race animation uses a standard sprint speed curve (top speed reached with a time constant of about 1.1 s) and finishes each lane at its converted time.
What this research can't tell you
The models assume the gauge reading is the wind the athlete ran in, which it often isn't. The 200 m, hurdles and jumps figures are averages from results, not a per-athlete model. Tall, upright sprinters catch more wind than smaller ones. Use converted times to compare and plan, not to claim marks.
References
- Quinn, M.D. (2004) The effects of wind and altitude in the 400-m sprint. Journal of Sports Sciences, 22(11–12), pp.1073–1081.
- Ward-Smith, A.J. (1986) Altitude and wind effects on long jump performance with particular reference to the world record established by Bob Beamon. Journal of Sports Sciences, 4(2), pp.89–99.
- Linthorne, N.P. (2016) Improvement in 100-m sprint performance at an altitude of 2250 m. Sports, 4(2), 29.
- Moinat, M., Fabius, O. and Emanuel, K.S. (2018) Data-driven quantification of the effect of wind on athletics performance. European Journal of Sport Science, 18(9), pp.1185–1190.
- Mureika, J.R. (2000) "Back-of-the-envelope" wind and altitude correction for 100 metre sprint times. arXiv preprint physics/0006057.
- scottishathletics (2016) Wind gauge: guidance for officials.
- Ward-Smith, A.J. (1999) New insights into the effect of wind assistance on sprinting performance. Journal of Sports Sciences, 17(4), pp.325–334.