When you’re trying to get pregnant, knowing when you’re ovulating is key because your egg only has a lifespan of 12 to 24 hours after you ovulate. An ovulation predictor kit, which detects the luteinizing hormone (LH) surge that occurs just before ovulation, is one of the easiest ways to determine the best time to have sex in order to increase your chances of getting pregnant. (Advanced ovulation kits also detect estrogen, which rises before the LH surge, letting you know sooner that you’re approaching peak fertility—ideal sperm can survive in the Fallopian tubes for five to six days.) To find the best ovulation predictor kits, our editors and women who were trying to get pregnant put 10 products to the test to see which ones offer clear, accurate results and are easy to use. We also looked at the price points in comparison to what you get from each product—an important thing to consider because the cost can add up for couples who are trying to conceive for several months. Here are the best ovulation predictor kits to help you pinpoint your most fertile days.