Figuring out if a female friend, coworker or acquaintance is gay can be a bit of an uphill battle. You don't want to come off as invasive or judgemental, especially when the person in question might not be ready to open up about her sexuality. But at the same time, you really want to know if your crush is in fact into girls.
Fortunately, there are some subtle signs that might clue you in. For example, she might mention that she often fantasizes about other women, or she may refer to herself in a sexual manner when talking about other girls. She also might be a lot more flirtatious when around you than she is with other people.
Another thing to consider is the way she talks about gay people in general. If she tends to use the word gay in its broader sense—meaning merry or lively rather than as a sexual term—it could be a sign that she's queer.
You can also gauge her interest in the LGBTQ community by how much she knows about it. If she can rattle off the names of a few prominent queer celebrities in no time at all, it's probably safe to say she's in the fold. But if Ellen Page, Cara Delevingne or Ruby Rose don't immediately spring to mind, it might be time to start asking her some questions about her interests. It might be the only way to find out for sure!