Scientists crack the formula for the ‘perfect backside’ – so how does yours measure up?
SOME people love them big and round, others prefer them tight and slight.
But scientists reckon the perfect backside has nothing to do with size.
It turns out how the aesthetic appeal of your bottom is all down to what's known as the golden waist-to-hip ratio.
This measures the waist at its smallest point and the hips at their largest point.
The higher the ratio, the more fat someone has around their middle, making their rear appear less curvy.
Two studies into the kinds of bums people find attractive found that the optimum formula for a woman is 0.65.
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This means the buttocks are about 35 per cent larger than the waist - similar to singer and actress Jennifer Lopez's famous behind.
For men, a gluteal trochanteric index (GTI) of 0.66 was most popular.
This was measured by dividing the distance from the thinnest point of the waist to the bottom of the buttocks by the widest part.
Swedish actor Alexander Skarsgård is the proud owner of such a tush.
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To discover what makes first class cheeks, researchers at Loma Linda University in California created eight digital images.
They then asked 1,146 men and women which they preferred.
The top scoring bum had a waist-to-hip ratio of 0.65, meaning the waist is narrow and the hips flare out, but not to an extreme.
In second place was 0.60 (comparable to singer Kylie Minogue), followed by 0.675, 0.75, 0.7, 0.5, and 0.8.
The least attractive had a slightly unnatural-looking ratio of 0.55, suggesting that society is shifting away from aspiring to be like hourglass icons Kim Kardashian (0.50) and Nicki Minaj (0.55).
There were no significant differences between age groups, genders and ethnic groups in their choices.
The said: "New ideal waist-to-hip ratios of 0.6 and 0.65 update the previous standards and indicate a more dramatic and 'curvier' new ideal, signalling an important preference paradigm shift."
The study into blokes, published in , was carried out by a team of surgeons from US.
It questioned 2,095 men and women aged 25 to 34 on their preference of five images of male bums.
The overall winner (GTI 0.66) was moderately sized, well-proportioned, with a bit of muscle.
Next was 0.64 (like Hollywood star Channing Tatum), then 0.68, 0.62, and 0.58.
The preferred lateral thigh to buttock ratio was 1.18, and the top scoring oblique projection angle was 60 degrees.
Lead author Ashit Patel said: "Our results demonstrate that there is a preferred male gluteal aesthetic.
"The findings suggest that a moderately enhanced, well-proportioned appearance is most desirable.
"Men and women favour a more projected male buttock with a more pronounced contour, but a narrow width with defined lateral depression.
"In our survey, raters thought the ideal male buttocks shouldn't be flat, but also shouldn't stick out too far.
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"The buttocks shouldn't be too wide, and should retain the characteristic dimple on the sides."
Both teams hope to use their findings to guide future plastic surgery techniques.