She's pout of this world! Formula proves Scarlett Johansson has the perfect kissable lips (but Emma Watson needs a bit of help)

• Women whose upper and lower lips are exactly same thickness are desirable 
• Scarlett hits perfect ratio along with British model Rosie Huntington-Whiteley
• But Harry Potter actress Emma Watson, 27, has a slightly narrower upper lip

Actress Scarlett Johansson has the most attractive lips on Earth – and that’s a scientific fact.

Researchers have determined that women whose upper and lower lips are exactly the same thickness are deemed to have the most desirable pouts.

And Scarlett hits the perfect ratio of 1:1 – stats The Avengers star shares with British model Rosie Huntington-Whiteley.

However, former Harry Potter actress Emma Watson is deemed less than perfect as she has a slightly narrower upper lip.

The findings come from a study of 560 plastic surgeons and the same number of members of the public, drawn from 35 nations. They were asked to look at photographs and choose those with most attractive mouths.

The study was led by Dr Paul Heidekrueger, of Munich, who has previously conducted similar work into the perfect buttock size and ‘the ideal ear placement in Caucasian females’.

Writing in the Journal Of Cranio-Maxillo-Facial Surgery, he concluded ‘a 1:1 lip ratio can apparently be considered most pleasing in females’. The second most attractive look was to have a slightly plumper lower lip.

But he conceded: ‘Our study represents current trends in aesthetics and may be subject to change, much like fashion.’

Cosmetic surgeon Gerard Lambe, of Manchester’s Reflect Clinic, said: ‘Lips are so important – they are an erogenous and attractive feature. We are zoned in on that part of the face. It is enormously important in our minds, for communication.

‘An even lower and upper lip tends to be most pleasing.’

But he said that bad plastic surgery caused a ‘very distorted body image’. ‘You only have to walk down the street and you see these horrendous pouts and these awful blown-up faces,’ he added.