In brief
- Speed guns use radar, while modern broadcast systems often rely on camera tracking to estimate ball speed.
- The figure shown is usually measured at or near release, not at the moment the ball reaches the batter.
- The ball slows down in flight and again off the pitch, so the speed a batter faces is lower than the speed displayed.
- Pace is only one ingredient: bounce, movement, accuracy and variation matter just as much.
The graphic flashes up on the screen a few seconds after the ball has gone past the bat: 148 kilometres per hour, or 92 miles per hour, depending on where you live. The commentators murmur approval. The crowd perks up. Yet behind that single number sits a surprisingly intricate set of technologies, and a few caveats that every fan should know.
The radar gun
The classic tool for measuring speed is the radar gun, which works on the Doppler principle. It sends out a radio signal and measures the change in frequency of the signal reflected from a moving object. The greater the change, the faster the object is travelling towards or away from the device. Police use the same idea to catch speeding drivers.
A radar unit placed behind the bowler's arm or at the sightscreen can follow the ball as it travels towards the batter. It tends to capture the speed fairly soon after the ball leaves the hand, because the signal is strongest when the ball is moving directly towards or away from the gun. As a result, the headline figure is often a reading from early in the ball's flight.
Cameras and tracking systems
Modern broadcasts increasingly use camera-based ball tracking, in which several high-speed cameras pick up the ball's position many times per second. By plotting where the ball is in successive frames and knowing the time between them, software can calculate the speed. The same data lets the system draw the flight path and predict where the ball would have gone, which is the basis of the technology used in lbw reviews.
Different systems may give slightly different results because they measure at different moments, use different calibration, or apply different smoothing. This is why a speed on one broadcast may not exactly match that on another, even for the same ball.
Where the speed is measured
A crucial point is that the figure usually describes the speed at, or just after, release. Once the ball is in the air, drag slows it down. Then, when it lands on the pitch, friction and the impact take away more speed again. The ball that arrives at the batter's bat is a good deal slower than the one that left the bowler's hand.
How much slower depends on the delivery and on the conditions, but it is a meaningful drop. A fast bowler's ball can lose a notable amount of pace by the time the batter faces it, and a short ball that bounces loses more than a full one that does not. This is the reason batters do not simply multiply a speed reading by their gut feeling.
| Stage | What happens to the ball |
|---|---|
| Release | Highest speed, usually where the figure is taken |
| In the air | Slows because of air resistance |
| Pitching | Loses more speed through impact and friction |
| Reaching the bat | Slower than the displayed figure |
What speed does not tell us
Speed is a bowler's most visible statistic, but it is far from the whole story. A bowler who delivers at 130 kilometres per hour but hits a perfect length, with seam movement and a steady line, can be more dangerous than one who sends down 150 with no control. The history of the game is full of bowlers who took many wickets at modest pace by knowing exactly where to put the ball.
Bounce matters as well. A ball that lifts steeply from a good length gives the batter less time and an awkward angle, regardless of the number on the screen. Late swing, seam and cut all change how hard a ball is to hit, and none of it shows in a speed reading.
Pace in the context of the game
A brief word on units and records
Speeds are shown in kilometres per hour in many countries and in miles per hour in others, so the same delivery can appear as two quite different numbers. It is worth remembering this before comparing figures from different eras and broadcasts. Early measurements were made with different equipment and methods, and the accuracy and consistency of speed readings have improved over time, so comparisons between generations should be made carefully.
The same goes for lists of the fastest deliveries ever bowled. Such lists are fun, but they depend on how and where the speed was measured, and not every claim has been recorded under comparable conditions. A healthy scepticism, and a love of the contest rather than the figure, is the best approach.
Even so, pace has an obvious appeal. A genuinely fast bowler changes how batters stand and play, and the sight of a ball reaching the keeper with a crack remains one of cricket's great spectacles. The speed gun gives us a language to compare, and allows us to note the rare few who have consistently approached or passed the upper reaches of the scale.
It is also worth noting that a bowler may touch his top speed only occasionally, so the average speed across a spell tells you far more about his sustained threat than a single peak reading ever could.
But treat the number with some humility. It is a snapshot, measured in a particular way, and a rough guide to a much more complicated reality. Enjoy the graphic, then watch the batter's feet. The truth about a fast bowler, as ever, is written in how the batter copes.
Frequently asked questions
How is bowling speed measured?
Speed is measured with radar guns using the Doppler effect, or by camera-based tracking systems that calculate speed from the ball's position in successive frames.
Is the displayed speed the speed the batter faces?
No. The figure is usually taken near release, and the ball slows through the air and off the pitch, so the batter faces a slower ball.
