When we consider the relationship between attractiveness and self-esteem, we often have conflicting intuitions.

On one hand, we think, attractive people must know they're attractive, and they must feel at least a little bit good about that. And we all know that people who aren't considered conventionally attractive can really struggle with their self-esteem.

On the other, we've all met beautiful people who seem unable to recognise that themselves. We might also know people who have very unfortunate looks, yet whose self-esteem appears undiminished by this fact. So is there any relationship at all between how attractive we are and how attractive we think we are?

As it turns out, there is – and it's one of the most important factors to consider in romance and matchmaking.

Most people think they're about a 7 out of 10. Strictly speaking, this means that a lot of us must be wrong (we can't all be above average). It also doesn't correspond with how most people rate each other: men's average rating for women is 4 out of 10, and women's average rating for men is about 2.6 out of 10. It seems like most of us think we're a lot better-looking than we are.

That said, it's worth noting that across studies, both men and women agree that men are less physically attractive than women. Fortunately, women are less interested in physical appearance than men (and happier to deviate from their own standards) when selecting partners. In more good news for men, women also agree less with each other on what's attractive than do their male counterparts.

There's another gender difference. When it comes to accuracy of self-perception, women tend to be significantly better at estimating their own attractiveness than men are (perhaps due in part to the fact that women are more self-critical about their appearance than men).

All of this has a substantial bearing on how we behave in the romantic sphere. How attractive we think we are determines whom we pursue. This means that two people of roughly equal attractiveness (as rated by third parties) and similar taste might choose very different partners as a result of their own self-perception.

In a way, this is common sense: most of us want the best partner we can find. If we don't believe we deserve, or are capable of winning, someone very good, we probably won't try for fear of experiencing rejection.

Of course, good looks aren't the only thing that makes someone desirable as a partner. Education, success, and income are the other main factors we tend to take into account when assessing our own or someone else's suitability as a partner. And one of the most important variables of all is self-esteem: how we present ourselves to others is shaped by how we see ourselves, and how we think others see us.

The constellation of these qualities – lifestyle factors, attractiveness to others, and self-esteem – is something we refer to at Swan as "eligibility." Eligibility is a good predictor of success in dating, because it encapsulates many of the criteria most people have in mind when searching for a partner. As part of our character assessment during the sign-up process, we ask people to rate their own eligibility on a scale of 0-14 – designed to shake off the cultural associations associated with the standard 10-point measure – and consider the results when making matches.

People who rate themselves as very eligible tend, unsurprisingly, to want their matches to be very eligible too. Interestingly, however, those who rate themselves as relatively ineligible tend not to want partners that others would consider desirable. This is likely due in part to the fear of rejection we mentioned above, as well as a desire to feel of equal status to their partner in romantic relationships. The tendency of humans to pair up with people of similar attractiveness and eligibility to themselves is known as assortative mating.

The good news is that eligibility is heavily determined by factors within our control. Whilst some aspects of our physical appearance are impossible (or very expensive) to modify, it's straightforward – if not easy! – to improve our level of education, our career trajectory, and our self-esteem. And improving how we see ourselves isn't just a question of psychological wellbeing: it'll determine the kind of person we date.