The speed of a punch is determined by several factors, including the technique, strength, and training of the person throwing the punch. In addition, the speed of a punch can also be influenced by external factors, such as the type of equipment used to measure the speed of the punch.

There are various ways to measure the speed of a punch, including using high-speed cameras or punch meters. However, these methods can produce different results, depending on the equipment used and the conditions under which the punch is thrown.
One of the most widely recognized records for the fastest punch is held by Bruce Lee, a legendary martial artist and actor who is widely regarded as one of the greatest martial artists of all time. In a speed test conducted by the Guinness World Records in 1971, Bruce Lee was recorded throwing a punch at a speed of 157 miles per hour (253 km/h).
However, it is worth noting that the accuracy and reliability of this measurement have been questioned by some experts. The test was conducted using a punch meter, which measures the speed of the punch at the point of impact, rather than the speed of the arm or fist throughout the entire motion of the punch. In addition, the punch was thrown at a stationary target, rather than a moving target, which may have affected the speed of the punch.
Other martial artists and boxers have also claimed to have thrown punches at incredibly fast speeds. For example, Muhammad Ali, one of the most famous boxers of all time, was known for his lightning-fast jabs and footwork. According to some reports, Ali was able to throw a jab at a speed of up to 60 miles per hour (96 km/h).
Similarly, Mike Tyson, another legendary boxer, was known for his explosive power and speed in the ring. In his prime, Tyson was recorded throwing a punch at a speed of around 40 miles per hour (64 km/h), which is considered incredibly fast for a heavyweight boxer.
In recent years, advances in technology have allowed for more accurate and reliable measurements of punch speed. For example, the Phantom v2512 camera, which is capable of recording at up to 1.4 million frames per second, has been used to capture the motion of a punch in unprecedented detail. Using this technology, researchers have been able to analyze the biomechanics of a punch and identify the factors that contribute to its speed and power.
One study conducted at the University of Liverpool in the UK used this technology to analyze the punching speed of boxers and martial artists. The researchers found that the fastest punch recorded in their study was thrown by Anthony Joshua, a heavyweight boxer who holds several world titles. Joshua’s fastest punch was recorded at a speed of 45 miles per hour (72 km/h), which is lower than the speed recorded for Bruce Lee’s punch in the Guinness World Records.
However, it is worth noting that the study was conducted using a different method of measurement than the Guinness World Records test. The researchers used a high-speed camera to record the motion of the punch throughout its entire motion, rather than measuring the speed of the punch at the point of impact.
In conclusion, the speed of the fastest punch ever is a matter of debate and interpretation. While Bruce Lee’s punch is widely recognized as one of the fastest ever recorded, the accuracy and reliability of the measurement have been questioned by some experts. Other boxers and martial artists have also claimed to have thrown punches at incredibly fast speeds, and advances in technology have allowed for more accurate and reliable measurements of punch speed. Ultimately, the speed of a punch depends on many factors, including the technique, strength, and training of the person throwing the punch, and the type of equipment used to measure the speed of the punch.