What F1 technical directors mean when they talk about ‘points’ of downforce

I was recently asked what was meant by ‘points’ of downforce. One often hears technical directors interviewed on television saying that after a collision resulting in body damage a car may have lost a certain number of points of downforce, but how much is this and what effect could it have on performance?

First, let’s examine how we measure downforce. In the context of a Formula 1 wind tunnel test, a 60% scale model of the car is run in the tunnel at a speed of 50 metres per second (about 110mph), these numbers being the maximum model size and air speed that the regulations allow.

A balance, which is effectively a very accurate force measuring device, will measure the aerodynamic loads that the model produces, which might, in the case of downforce, be in the region of 4kN. A kilonewton (kN) is a measure of force roughly equal to 225lb or 100kg.

The real car, however, on the circuit, may produce over 12kN at this speed, but as the downforce increases with speed, at 180mph the same car would produce over 34kN.

What this means is that we can’t express downforce in Newtons as the number would depend on the scale of the device we were measuring it on and the airspeed at which we were measuring.

To get round this problem, engineers like to express downforce in a non-dimensional form. What this means is that they can express the downforce, or indeed the drag, as a number that has no units but which, when used as a coefficient in a simple formula, will yield the downforce at any given speed or scale.

This coefficient is generally known as the lift coefficient and, as we are dealing with downforce, is negative. 

The reference point for calculations is normally the frontal area of the car – but teams vary in the numerical value used

Photo by: Red Bull Content Pool

So far so good, but unfortunately the simple formula used to calculate the downforce contains a term that relates to a reference area.

Normally the frontal area of the car is used. Why this presents a problem is that different teams use different values for the frontal area. Some use a reasonably exact number of 1.47 square metres, some approximate this to 1.5 and others say it’s only a number so use 1.0.

When comparing your own results between tests, of course this doesn’t matter, but if you’re comparing the lift coefficient between a team using 1.5 square metres with another using 1.0, there will be a considerable difference between them.

So, let’s consider a team is using a value of 1.5 square metres for their frontal area, then a current 2025 car would have a lift coefficient of around –5.5 (depending on the exact conditions considered).

We would not describe the size of our kitchen in fractions of a kilometre but instead use metres and decimal points of a metre

This is the number that the team’s aerodynamicists will be trying to improve. This is not easy, particularly with a mature set of regulations. To improve that number from –5.5 to –5.6 would take many hundreds of wind tunnel experiments, each one yielding a tiny fraction of improvement.  

We therefore need a way of expressing these smaller improvements with a convenient measure in much the same way that we would not describe the size of our kitchen in fractions of a kilometre but instead use metres and decimal points of a metre.

Aerodynamicists therefore split the lift and drag coefficients into hundredths and call each one of these a point. So, if our coefficient of lift is improved from –5.50 to –5.51 (negative, remember, as we are interested in downforce), we can say it has improved by a point.

So now we can think about what effect a loss of some points of downforce, brought about perhaps by damage, can have on the car’s performance.

Any loss of points is unsurprisingly a particular disadvantage at the Hungaroring

Photo by: Alpine

Of course, the answer will vary from circuit to circuit. Some are very sensitive to downforce while others are less so.

It’s not hard to imagine that a circuit like Hungaroring, with lots of medium-speed corners, will reward high downforce more than, say, Baku, which is mainly straights and low speed corners.

However, if we take an average, we could say that a loss of 10 points of downforce would equate to a lap time increase of around three tenths of a second.  

So what level of damage might lead to a loss of 10 points of downforce? That’s a much harder question to answer as each surface of the car is designed to work in harmony with the others.

For some the interaction may be weak and damage will not lead to significant performance loss. For other areas, what may seem trivial damage can be catastrophic.

So next time a technical director blames lack of performance on a 30-point downforce loss due to damage, you just have to believe them!

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Ferrari reckoned Lewis Hamilton’s collision with a groundhog in Canada cost him around 20 points in downforce

Photo by: James Sutton / Motorsport Images