Running: what should be my speed for a given ETA?

With all the techno onboard, on your wrist or on your humerus (upper arm), you now have access to your instant speed, and in particular, to your average speed.  The benefit of knowing your average speed is to manage your energy and your reserves while racing to reach your goal: covering the distance in a given time or less.
In this article, I will reveal the formula that gives ETA as a function of your average speed, and I will also draw reference charts that you can refer to for your next races.
Running: what should be my speed for a given ETA?

The speed = f(race time) equation

Below are the different expressions of the equation that binds average speed and ETA (race time).
Running: what should be my speed for a given ETA?

Légend :
d : distance ; t : time ; v : velocity (speed)
dkm : distance, expressed in kilometers
tmin : time, expressed in minutes
vkm/h : speed, in kilometers per hour.

Attention if you evaluate these equations with numerical values: if you want to use seconds on top of minutes (which is not common in these kind of problem), you will have to convert the seconds into minute decimals, i.e.  divide the seconds by 60.

Example : 43 minutes and 20 seconds, don’t use 43.20 in the equation, but rather 43 + 20/60, so 43.3333.

Example of a numerical evaluation to calculate the necessary average speed

Example of a 10 km run, thus dkm=10 ; you’re aiming at 50 minutes, thus tmin = 50 ; the equation supplies vkm/h = 60*10/50 = 12 km/h.  Meaning you will have to run at an average speed of 12 km/h to cover the distance in 50 minutes.

Reference charts

I’ve drawn up these charts for your convenience, with classical distances and running times.
The values in the charts are the average speeds in km/h that you need to run at for the corresponding ETAs.

Too low or unlikely speeds have been removed.
Reminder: 21 097 m is a half-marathon’s distance,
42 195 m is a marathon’s.

 

distance / time 20 min 25 min 30 min 35 min 40 min 45 min 50 min 55 min 1:00 1:05 1:10 1:15 1:20 1:25
5 km 15.00 12.00 10.00 8.57 7.50 6.67 6.00              
10 km     20.00 17.14 15.00 13.33 12.00 10.91 10.00 9.23 8.57 8.00 7.50 7.06
20 km               21.82 20.00 18.46 17.14 16.00 15.00 14.12
half-marathon               23.01 21.10 19.47 18.08 16.88 15.82 14.89

(continued)

distance / time 1:30 1:35 1:40 1:45 1:50 1:55 2:00 2:05 2:10 2:15 2:20 2:25 2:30 3:
10 km 6.67 6.32 6.00 5.71 5.45 5.22 5.00              
20 km 13.33 12.63 12.00 11.43 10.91 10.43 10.00 9.60 9.23 8.57 8.00 7.50 7.06 6.67
half-marathon 14.06 13.32 12.66 12.06 11.51 11.01 10.55 10.13 9.74 9.04 8.44 7.91 7.45 7.03
marathon             21.10 20.25 19.47 18.08 16.88 15.82 14.89 14.07

(continued)

distance / time 3:10 3:20 3:30 3:40 3:50 4: 4:20 4:40 5h 5h20 5h40 6h00 6h30
5 km                          
10 km                          
20 km 6.32 6.00 5.71 5.45 5.22 5.00              
half-marathon 6.66 6.33 6.03 5.75 5.50 5.27              
marathon 13.32 12.66 12.06 11.51 11.01 10.55 9.74 9.04 8.44 7.91 7.45 7.03 6.49

pace/speed conversion chart

pace (min/km) 3:00 3:15 3:30 3:35 3:40 3:45 3:50 3:55 4:00 4:10 4:20 4:30 4:40 4:50 5:00 5:15 5:30 5:45 6:00 6:30 7:00
speed (km/h) 20.00 18.46 17.14 16.74 16.36 16.00 15.65 15.32 15.00 14.40 13.85 13.33 12.86 12.41 12.00 11.43 10.91 10.43 10.00 9.23 8.57

Practical application: the possible race strategies to reach your goal

Start your race at the same speed as the average speed supplied by the reference chart.  Or . . . start slower, then accelerate over the last kilometers to increase it, until your average speed equals the one given in the charts.
This latter method ensures a good warm up, then a steady and controlled cruise speed, and finally will allow you to gauge the amount of risk you can take towards the end if you tap in to your reserves, to grab a few seconds or minutes.  However, don’t accelerate too late towards the end, especially during long races, as your average speed will barely vary . . .

What if I want to know my ETA for a given speed?

It is the reciprocal problem to the initial topic’s question.  The speed-time equation allows you to swap speed and time.Running: what should be my speed for a given ETA?

Example of a numerical evaluation for an ETA

Example of a half-marathon, thus dkm=21.1 ; you’re thinking of running at 10.5 km/h, what would your ETA be?
The equation gives tminutes = 60 x 21.1 / 10.5 = 120.57.  Therefore 2 hours and 0.57 minutes, wait, I didn’t say 57 seconds! So you have to multiply by 60 to get seconds, so 0.57 x 60 = 34 secondes, roughly.  Thus a total of 02:00:34.  Good luck!

(1045 views)
revised 05 October 2017 by M. Fabien Haddadi M Sc. Fab
Tropicalm