They can be bought over the counter and are easy to use. How do ovulation tests work? Just like a home pregnancy test, an ovulation test works by detecting hormones in your urine. That means it's another "pee on a stick" test. In this case, they detect a surge in luteinizing hormone (LH). This hormone briefly dominates when an egg is released from the ovaries, and that short window makes for a very effective at-home ovulation test. Unlike home pregnancy tests, ovulation tests work best in the afternoon, because that is the time of day when the luteinizing hormone synthesizes. You don't need to use ovulation tests every single day of your cycle of course. The key to success is finding out approximately when in your cycle you ovulate.
The best way to get a feel for this is by using an ovulation calendar. In short, an ovulation calendar calculates the approximate date of your ovulation when you are aware of the length of your cycle. Armed with that information, you can start using ovulation tests a few days before you expect your ovulation. When you are ovulating, the ovulation test will let you know. Mine came up with smiley faces for ovulation, and sad faces when ovulation was not taking place.