VAM Calculator

Theory

Average Ascension Speed (VAM)

The Average Ascent Rate (VAM) is a metric used in Trail Running to measure an athlete's climbing efficiency. It indicates the difference in altitude that an athlete can cover in an hour, regardless of the gradient of the climb.

The VAM is a parameter widely used in trail running, cycling and mountain activities to measure an athlete's ability to quickly climb altitude.

What is VAM?

The VAM indicates the positive difference in altitude (i.e. the meters of ascent) that an athlete can cover in an hour. It is expressed in meters/hour (m/h).

How is it calculated?

The basic formula of VAM is:

$$ \textcolor{var(--primary-color)}{\displaystyle \Large \textbf{VAM} = \frac{\text{Positive Difference in Height (m)}}{\text{Time Taken (h)}}} $$ $$ \textcolor{var(--primary-color)}{\displaystyle \Large \textbf{VAM} = \left( \frac{\text{Positive Difference in Height (m)}}{\text{Time Taken (m)}} \right) \times 60} $$

Difference in altitude is expressed in metres.

Time in minutes or in hours is the time taken to cover the difference in altitude.

Practical example:

If an athlete ran a trail and covered 600 meters of positive difference in altitude in 30 minutes (0.5 hours), his VAM will be:

VAM = 600 / 0.5 = 1200 m/h

If an athlete covers a difference in altitude of 400 meters in 20 minutes, the VAM will be:

VAM = (400 / 20 ) * 60 = 1200 m/h

Usefulness of VAM in Trail Running

It allows you to compare performances between athletes on terrains with different slopes.
It helps to estimate the time needed to complete a climb.
It is a good indicator to evaluate the level of preparation for climbing.

Relationship between VAM, Gradient and Weight

The VAM formula does not directly include gradient or weight. However, both of these factors influence VAM indirectly:

Gradient

A steeper gradient requires more energy to cover the same amount of elevation, so it can reduce VAM. Gradient is a critical factor that affects climbing speed, but it is not directly included in the VAM formula.

Weight

Body weight can influence VAM as a lighter athlete may have an advantage in terms of energy efficiency during climbs. However, weight is not a parameter included in the VAM formula.

Practical considerations

In practice, VAM is a measure that helps evaluate climbing efficiency independently of the gradient, but the gradient itself and body weight are factors that influence real performance.

To optimize VAM, athletes can work on climbing technique, endurance and body weight management, although these are not directly included in the VAM calculation.

Gradient (Gradient) and VAM

The gradient of a climb is calculated with:

$$ \textcolor{var(--primary-color)}{\displaystyle \Large \textbf{Gradient} (\%) = \frac{\text{Positive Difference in Altitude}}{\text{Horizontal Distance}} \times 100} $$

If you want to calculate the gradient use our calculator: Gradient Calculator

Weight and VAM with Michele Ferrari's Formula

The athlete's weight affects the power needed to maintain a certain VAM. The relationship between power and VAM is:

$$ \textcolor{var(--primary-color)}{\displaystyle \Large \textbf{VAM} = \frac{\text{Power} \times 1000}{\text{Weight} \times 9.81}} $$

Example Calculation with Michele Ferrari's Formula

Data of a typical Trail Running athlete:

Weight: 65 kg
Average power developed uphill: 4 W/kg
Total power: 4 × 65 = 260 W

Calculating VAM:

VAM = (260 × 1000) / (65 × 9.81)
VAM = 260000 / 637.65 ≈ 408 m/h

Interpreting the result

This athlete with 4 W/kg of specific power would be able to gain approximately 408 meters of positive elevation gain per hour.

To improve VAM, he could:

Increase power with strength and specific resistance training.
Reduce body weight (if optimizable) to improve W/kg.

In trail running, a VAM of 400-700 m/h is common among well-trained amateurs, while professionals can exceed 1000 m/h on steep climbs.

Use

There are two modes: VAM and VAM (Power and Weight)

VAM

Choose the Measurement System:

Metric
Imperial

Select the unit of measurement:

If you have chosen the Metric System, you can enter:

Elevation (m or km)
Duration (h m s)

If you have chosen the Imperial System, you can enter:

Elevation (ft, yd or mile)
Duration (h m s)

Enter the values and calculate:

Your VAM

VAM (Power and Weight)

You can enter:

Specific Power (Watt/kg)
Weight (kg)
Average Power (Watts)