Running in 10 mph Wind - How Much Slower per Mile?

A 15 mph wind and a 9:00 mile, by the numbers

A tailwind gives back what a headwind takes. It does not, and this running headwind calculator shows by how much. Give it your calm-day pace, your weight, the wind from the forecast and its direction, and it returns the pace that costs the same effort in that wind, the change per mile or kilometer, and the loss over a whole race. For a 160 lb runner at 9:00 per mile, a 15 mph forecast headwind is worth +58.0 s per mile, while the same wind from behind gives back only 14.6 s.

+58.0 s

per mile into a 15 mph forecast wind, 9:00 pace, 160 lb

-14.6 s

per mile with the same wind behind you

+21.7 s

per mile on an out-and-back course

76%

of the forecast wind reaches a runner on open ground

From the forecast to a pace in six choices

Units - pace per mile and pounds, or pace per kilometer and kilograms.
Calm-day pace and weight - the pace you run at this effort with no wind, in minutes and seconds, and your body weight. Weight sets the frontal area the wind pushes on.
Wind speed and unit - the average speed, not the gusts, in mph, km/h or m/s as your forecast gives it.
Where the speed comes from - a forecast, which is measured 10 m above the ground, or a reading from a handheld meter at your height.
Terrain - for a forecast only: open ground such as a lakefront or farmland, or suburbs and trees, where much less of the wind reaches you.
Direction and distance - head, quartering, cross, tail or an out-and-back course, plus an optional race distance. Then read the pace, the change per mile and the two tables.

What the calculator is actually computing

Air pushes back on every runner, wind or no wind. On a calm day at 9:00 per mile that drag takes about 1.8% of a 160 lb runner's effort, and the share rises with speed: 3.0% at 7:00 per mile, 1.2% at 11:00. The force comes from the drag equation with a drag coefficient of 0.8 and a frontal area estimated from body weight, the values Pugh measured on runners and that later papers still use.

A headwind raises the air speed against you, so the force grows with its square. Wind from the side adds to the air speed too, which is why a pure crosswind still costs 9.3 s per mile in the example. To turn force into effort the calculator uses the result of da Silva, Kram and Hoogkamer: every 1% of body weight of horizontal resistance raised metabolic power by 6.13% on average. It then looks for the speed at which your effort in the wind matches your calm-day effort, and prints that as a pace.

The forecast part matters as much as the physics. Weather services report wind at 10 m. At about 1.5 m the wind is slower, by how much depends on what stands around you. The calculator uses the usual power law: 76% of the forecast on open ground and 57% in suburbs with trees. The same 15 mph headwind costs +58.0 s per mile on open ground and +38.3 s among houses.

Headwind, tailwind and out-and-back by forecast speed

The reference runner weighs 160 lb, runs 9:00 per mile on a calm day and trains on open ground. Each cell is the change per mile at the same effort.

Forecast wind	Headwind	Tailwind	Out and back
5 mph	+13.8 s	-8.0 s	+2.9 s
10 mph	+33.2 s	-10.0 s	+11.6 s
15 mph	+58.0 s	-14.6 s	+21.7 s
20 mph	+1:28.1	-25.1 s	+31.5 s
25 mph	+2:03.6	-41.2 s	+41.2 s
30 mph	+2:44.5	-1:02.3	+51.1 s

The second table keeps the 15 mph forecast and changes the runner instead. Slower runners spend more minutes in the wind, so they lose more seconds per mile even though drag takes a smaller share of their effort. Lighter runners lose a little more, because their frontal area shrinks more slowly than their weight.

Runner, 15 mph forecast	Headwind	Tailwind	Out and back
7:00 /mi, 160 lb	+49.9 s	-13.7 s	+18.1 s
9:00 /mi, 160 lb	+58.0 s	-14.6 s	+21.7 s
11:00 /mi, 160 lb	+1:05.5	-17.5 s	+24.0 s
9:00 /mi, 120 lb	+1:03.6	-16.1 s	+23.8 s
9:00 /mi, 200 lb	+53.9 s	-13.5 s	+20.2 s

Five facts about wind that change how you read a split

The loop never breaks even. At 15 mph the way out costs 58.0 s per mile and the way back returns 14.6 s, so a half marathon at 9:00 effort finishes 4:44 later than on a calm day.

Even the fastest marathoner pays for still air. Da Silva and colleagues put the drag on a runner at 2-hour marathon pace at 7.07 N, or 1.39% of body weight, which takes 7.8% of the metabolic power.

The study only went to 8 N. Its runners were held back by forces of 0, 4 and 8 N, never pushed. A strong headwind easily exceeds that, so the result warns you when the force passes 3% of your weight, and the tailwind figures are the same rate run in reverse.

Individual runners differ. The 6.13% is an average; the twelve runners in the study ranged from 4.17% to 8.14%, so your own loss can be a third smaller or a third larger.

Shelter is worth more than you think. Running behind other runners or among buildings lowers the air speed on your body, and the forecast-to-ground step alone moves the 15 mph example from 58.0 to 38.3 s per mile.

Who reaches for a headwind calculator

A marathoner on an out-and-back course who wants to know whether a goal is still realistic in a forecast wind. At an 8:00 calm-day pace and 150 lb, a 12 mph forecast adds 14.4 s per mile over the loop, which is 6:17 over 26.2 miles.

A runner doing a tempo session on a windy day who wants the effort right rather than the pace: into the wind the target slows, with the wind it speeds up, and the watch stops looking like a failure.

A coach reading race results who needs to explain why a strong group ran a minute slower than last month on the same course.

A runner deciding on a route: start into the wind while the legs are fresh, and come home with it behind you.

Wind and pace, asked and answered

How much does a headwind slow you down when running?

It depends on the wind at your height, your pace and your size. For a 160 lb runner at 9:00 per mile, a 10 mph forecast headwind on open ground costs about 33 s per mile, and 20 mph costs 1:28. Because drag grows with the square of the air speed, doubling the wind more than doubles the loss.

Should I use the forecast or a wind meter?

Either, as long as you tell the calculator which. A forecast is for 10 m above the ground and gets scaled down for terrain. A handheld meter held at chest height already reads the wind you feel, so pick the ground-level option and the reading goes in unchanged.

How is this different from the weather pace adjustment calculator?

The weather pace adjustment calculator combines heat, humidity, wind and surface into one correction. This one does wind alone, in more detail: forecast or ground reading, terrain, five directions, the out-and-back balance and your weight.

Why does a crosswind slow me down at all?

Because the air hitting you is the sum of the wind and your own running speed. A wind from the side makes that combined air faster and turns it slightly, so the part pushing against your direction of travel grows. In the 15 mph example a pure crosswind costs 9.3 s per mile.

Related tools

Cycling Drafting Calculator

Watts saved on a wheel, in a paceline or a peloton, against riding alone at the same speed - See the calculator

Triathlon Calculator

Finish time and splits from your swim, bike and run paces, with the Ironman cutoffs - See the calculator

Weather Pace Adjustment Calculator

Heat, humidity, wind and surface folded into one pace correction - See the calculator

Half Marathon Splits Calculator

Even, negative or easy-start splits for a goal time - See the calculator

Tanda Marathon Predictor

A marathon time from eight weeks of training mileage and pace - See the calculator

VDOT Calculator

Training paces and race predictions from one race result - See the calculator

Treadmill Calculator

Treadmill speed and incline as an outdoor pace, for the days the wind wins - See the calculator

Running Cadence Calculator

Steps per minute and step length from pace or a 30-second count - See the calculator

Running in 10 mph wind: how much does it slow you down?

Parameters