Researchers had a long hard think while mulling over the data (Picture: Getty Images/ Shutterstock)

Academics have answered some long unanswered questions about the penis and erections.

A scientific definition has been created over whether a man’s penis can be classed as a ‘grower’ or a ‘shower’.

Confirming the distinction – complete with official measurements – could help doctors make surgical decisions in the future.

‘Growers’ are men whose penises increase in size by more than 56% when erect compared to when flacid.

‘Showers’ are those whose penises increase in size less than 31% when erect compared to when flacid.

According to the research – conducted in Spain – most men actually fall into the ‘grey zone’ in between the two categories.

Only 24% of men are classed as growers, while a quarter are classed as showers.

Many men also fall into the ‘grey zone’ are aren’t showers or growers (Picture: Shutterstock)

Some penises appear bigger when erect than others (Picture: Shutterstock/PhotoStockPhoto)

Dr Manuel Alonso-Isa, a urologist at the University Hospital HM Puerta del Sur in Madrid, Spain, helped lead the study.

He said: ‘It is important to be able to predict if a patient is a grower or a shower as when we see them, they are usually in a flaccid state.

‘If they grow a lot when they get an erection, it might mean they need a different surgical approach compared to someone who doesn’t grow much.’

The study also revealed that showers tend to have longer penises when flacid.

For the research, urologists based at three hospitals and a clinic in Madrid conducted ultrasound scans on 225 men in both flaccid and then erect states, after giving them an injection.

When they examined the data, the extent of the men’s penis growth followed a pattern that allowed them to set parameters on each category.

The research further suggests that the size of the fibrous tissue known as the tunica albuginea, which surrounds the spongy erectile tissue inside the penis, did not predict how much a man’s penis might grow.

Dr Alonso-Isa added: ‘In the meantime we have defined what constitutes a “grower” or a “shower” in a scientific way, which will be important for the future.’

Official findings from the study are to be presented at the European Association of Urology (EAU) Congress in Milan.

Commenting on behalf of the European Association of Urology, Professor Maarten Albersen, a urologist at the University of Leuven, Belgium, said while there may not be any medical consequences to being a shower or a grower, it was something that often weighed on the minds of patients.

He said: ‘This is a frequent area of concern for our patients and the emphasis should be on normalising baseline and erectile length for all.’

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Researchers had a long hard think while mulling over the data.