1. OPKs are more precise than other methods of monitoring ovulation. Used correctly, the major-brand OPKs are more than 97 percent effective in detecting an LH surge, which is used as a marker for ovulation.
2. OPKs are convenient. OPKs are used only in the middle of your cycle, during the time when you would be most likely to ovulate (note that it helps to have a sense of your typical cycle length, so start keeping track now if you haven't already). Other methods, such as charting your basal body temperature (BBT), require a daily commitment.
3. OPKs are widely available. You can get them over the counter at drugstores, pharmacies, and even major supermarkets and convenience stores, without a prescription.
4. OPKs are easy to use. Ovulation kits are similar to home pregnancy tests -- you simply urinate on the test stick, activating a chemical that can detect your LH surge. Most OPKs contain between five and nine test sticks.