Sad but true.

Dude, if you're thinking about popping the question to a gal you KNOW is way out of your league, you may want to give your engagement ring some extra thought. And you're OK with that.

The UGLIER a guy is, the more he's expected to spend on an engagement ring, according to a new study.  But maybe guys don't mind . . . because the study also found that the more attractive a guy found his girlfriend, the more he was willing to spend on the ring. And there is research to back it up.

Women expect a pricier ring with a big stone if they think their partner is ugly to make up for their poor looks, and men are more likely to fork over a boatload of greenbacks on a flashy rock if their wife-to-be is beautiful, scientists found.

Western Oregon University researchers quizzed 590 people to find out whether looks influence the choice and expectations of engagement rings.

Participants saw photos and brief descriptions of someone of the opposite sex who had been pre-rated as 'attractive' or 'unattractive'.

Researchers then had each subject imagine the person was their partner.

Women had to choose the smallest ring they were willing to settle for offered by the man in the photo.

In turn, the guys were asked the size of ring they would buy for their dream land girlfriend.

The results revealed men were more willing to buy larger, more expensive rings when they imagined themselves proposing to a beautiful woman. Women are happy to settle for an ugly partner if he brings something else to the table, like being financially stable.

As you might expect, men typically use symbols of success, including wealth, to draw in more desirable partners, while women were found to expect more expensive rings with larger rocks if they saw themselves with an unattractive partner.

The study also found that women who rated themselves as attractive were more likely to go for larger, more expensive rings, regardless of their partner's looks.

A previous study by economists in 2014 found that the more expensive the engagement ring, the more likely the couple would get divorced later.

They analysed records of 3,000 engagement ring purchases to come to the conclusion.

The idea that a man should pay a month’s salary for an engagement ring was a marketing ploy concocted by De Beers in the 1930s, which caught on worldwide.

More on this and the 4 scientifically proven traits women find attractive in men here.