How to Read an Ovulation Test?

by | Aug 12, 2019

When trying to conceive, knowing when ovulation happens gives you more control and maximizes your chances of success. You may have spent a lot of time researching how to read the faint line on an ovulation test kit. And you may just not see a positive result after testing for a while. You may wonder how to use an ovulation test properly to get the most accurate test result. Our egg only lives up to 12 – 24 hours after the ovulation.

woman and book

You don’t want to miss ovulation or any fertile days. Let’s look deeper into ovulation tests.


What is an ovulation test kit?

An ovulation test kit is also called an ovulation prediction kit or OPK. It detects the luteinizing hormone or LH surge. Doctors often order blood tests to test the LH level in blood. At home, you can buy ovulation test kits to continuously test your LH level.

Ovulation is tightly regulated by hormone levels. The surge in LH happens about 24-36 hours before ovulation.

An ovulation test kit has two lines. The first line is the control line. It tells you if the kit is working. The second line is the test line.

When it detects the LH surge, the second line changes to similar darkness or darker than the control line.


How does an ovulation test kit work?

An ovulation test kit works by testing how much fertility hormone presents in your urine, to determine your ovulation.

Once the ovary releases an egg, the egg has only 12 – 24 hours of lifespan to be fertilized by sperm. These 12 – 24 hours are your most fertile time of the menstrual cycle. It is also the time to have intercourse to maximize your chance of conceiving. According to the New England Journal of Medicine, the chance of pregnancy right the 24 hours is zero.

Probability of conceptions on specific days near ovulation. For example, day 0 is the ovulation day. day -1 is the day before ovulation, and day 1 is the day after ovulation, etc.

Probability of conceptions on specific days near ovulation. For example, day 0 is the ovulation day. day -1 is the day before ovulation, and day 1 is the day after ovulation, etc.

The good news is that sperm can survive up to 5 days in the woman’s reproductive tract. Your fertile days are the 5 days leading to ovulation and ovulation day. Because the ovulation test kits detect the LH surge only, they are only able to identify the 2 days near ovulation. For this reason, many people start testing when approaching the fertile window.

Types of ovulation test kits

Urine-based ovulation prediction kits

These kits detect the LH surge before the release of an egg. Like a pregnancy test, collect your urine in a clear cup or urinate on the stick directly. Two-color bands should appear on the stick. You have a positive test result when the second line is in a similar shade or darker than the first line.

A positive test result means you are ovulating 24-36 hours. Between now and then is the best time to have intercourse if you are trying to conceive.


  • Many women believe they are easier to use than taking basal body temperature (BBT) in the morning. You don’t have to remember to keep a thermometer on your nightstand. You don’t need to worry about waking up at night affecting the temperature readings.
  • They are more effective than BBT. It can be a problem to accurately read the result of BBT. The 0.5 Fahrenheit is a rather small difference between fertile and non-fertile days.
  • Moreover, BBT increases after ovulation happens. It captures your last 12 hours of the fertile window out of the 5 – 6 fertile days per cycle. If used properly, BBT confirms ovulation but doesn’t predict ovulation.
  • Ovulation test kits don’t need to be used right after you wake up. Morning urine is recommended by many brands. But you don’t have to test with morning urine if you limit fluid intake for at least 2 hours before the test.
  • Ovulation test kits are more comfortable to use than checking your cervical mucus. It can take time to learn how to read your cervical mucus change.



  • The tests can give you false-positive or false-negative results. The hormone levels can differ greatly from woman to woman and cycle to cycle. If you have a low hormone level, or your hormone level fluctuates, you may end up missing your fertile days.
  • Some people have trouble reading the test results. You are not alone. The second faint line is a common problem. It can be hard to tell if the second line is dark enough to count as a positive result.
  • The test result can vary. Different brands and lots can have a slightly different color change. The darkness of the line in one kit doesn’t necessarily apply to the other kits.
  • Ovulation test kits may not work for women with the polycystic ovarian syndrome (PCOS), or women who have an irregular cycle. Both are associated with irregular and unique hormone patterns. Ovulation test kits can’t adapt to these variations.


Fertility monitors

Fertility monitors are electronic devices that track ovulation digitally. They are mainly used to predict ovulation and detect peak fertility time. They are usually more expensive but easier to use than ovulation test kits. The device records your testing results and helps to identify the ovulation.

There are two kinds of fertility monitors in the market. The traditional type and an advanced type, such as the Mira fertility tracker.


Pros and Cons

  • The traditional fertility monitors determine your ovulation based on a fixed threshold, which is usually the population average. This can still lead to missed peak or positive results all the time. Mira solves this problem by measuring your actual hormone concentrations. You are unlikely to miss a fertility peak even if you have variable menstrual cycles.
  • The traditional fertility monitors often don’t have BlueTooth connectivity. This means your test results can only be viewed from the device screen, but accessible wherever you have your phone. It is easier to track fertility with Mira. Your test results sync onto the Mira App instantly.
  • One common problem with fertility tracking is the variable cycle and hormones. Mira’s smart algorithm learns your cycle pattern. It also dynamically calculates when you should test so you don’t have to test every day.
  • Both types of fertility monitors don’t require reading the result by naked eyes.
  • Both types of fertility monitors time tests need to be done. So you don’t have to worry about testing too early or testing too late.
✔️ Medically Reviewed by Banafsheh Kashani, MD, FACOG

Banafsheh Kashani, MD, FACOGBanafsheh Kashani, M.D., FACOG is a board-certified OB/GYN and specialist in reproductive endocrinology and infertility at Eden Fertility Centers, and has been treating couples and individuals with infertility since 2014. Prior to joining Eden Centers for Advanced Fertility, she was practicing as a top fertility specialist at Kaiser Permanente in Orange County and Reproductive Fertility Center. Dr. Kashani has received numerous awards throughout her years of study and medical training. 

Dr. Kashani has conducted extensive research in female reproduction, with a specific focus on the endometrium and implantation. Additionally, Dr. Kashani has authored papers in the areas of fertility preservation, and fertility in women with PCOS and Turners syndrome. She also was part of a large SART-CORS study evaluating the trend in frozen embryo transfers and success rates.

Dr. Kashani is a fellow of the American Congress of Obstetricians and Gynecologists. In addition, she is a diplomat of the American Board of Obstetrics and Gynecology and an active member of the American Society of Reproductive Medicine (ASRM) and Pacific Coast Reproductive Society (PCRS). She is also a member of the Society of Reproductive Endocrinology and Infertility (SREI).

Order Your Mira Today

Ready to easily, precisely, and automatically track your ovulation cycles? Let Mira take the guesswork out of getting pregnant, so you know exactly when to conceive.

Reserve Your Mira Today

Ready to easily, precisely, and automatically track your ovulation cycles? Let Mira take the guesswork out of getting pregnant, so you know exactly when to conceive.