Ovulation Prediction Kits (OPKs) – What Are They and How to Use Them

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Everything you need to to know about ovulation prediction kits, or OPKs, and how to use them.

Why should I use OPKs, or ovulation prediction kits?

When you are ready to get pregnant, your fertile window can be tricky to detect if you haven’t been paying much attention.

As women, we are taught that we ovulate on day 14, and then get a period on day 28 every cycle.

But in reality, the odds of having a “perfect” cycle are a lot less. So much so, that only 10% of women have typical 14-day ovulation and a 28-day cycle. 10%!

That leaves the remaining 90% guessing.

And even if you do have a 28-day cycle, it doesn’t necessarily mean you ovulate on day 14.

So what do you do? When you are ready to conceive, and you have no idea when you ovulate, how can you narrow it down?

One way is using OPKs, or ovulation prediction kits.

What Are Ovulation Prediction Kits (OPKs)?

OPKs are test strips that you can use at home to detect ovulation.

When you are about to ovulate, your body releases LH or Luteinizing Hormone. This can be detected in your urine, similar to detecting HCG when you become pregnant.

With OPKs, you can test daily, until you see a peak, which means you will release an egg within the next 12-36 hours.

Ovulation tests are different than pregnancy tests in that you are reviewing the color/darkness of the test line vs. any line at all. For pregnancy, you are trying to detect any HCG to determine you are pregnant, so if you receive a faint line, it’s still positive.

With OPKs, a faint line is actually a negative result. You want the test line to be as dark or darker than the control line.

How Do I Use Them?

To use ovulation prediction kits, you pee into a small cup, and then dip the test strip into it (for however long it states in the instructions), and then wait approximately 3-5 minutes (again, read the specific instructions for your kind).

Waiting to read results of your OPKs.

Once the time is up, look at the test to see your results.

When using OPKs, your best time to test is between the hours of 10 am and 4 pm.

You don’t want to use your first-morning urine (FMU), as the LH in your system will be diluted in the morning.

If you can’t test during that window because if your schedule, don’t worry, you can still test. Just try to avoid using FMU.

You’ll also want to try and test at the same time every day.

Finally, avoid drinking anything for at least 2 hours before the test. If your urine is too diluted with water, it may give you a false negative.

What Does a Positive vs. Negative Result Look Like?

This is always the confusing part. As I stated earlier, when you take a pregnancy test, you are just looking for those two lines, no matter how dark.

But with OPKs, the color and darkness of the line matter.

Some women have a constant low level of LH in their system, so will always see some sort of faint line. If yours is completely non-existent, don’t worry. Your LH should only spike near ovulation.

I mention this because I am about to show my own examples, but don’t worry if they don’t look exactly like it.

What a negative result looks like on ovulation prediction kits, or OPKs.

As you can see, some can be confused as positive results, but once you see what a true positive looks like, you’ll quickly know the difference.

What a peak and positive result looks like on an ovulation prediction kit (OPK).
All 3 tests were taken on the same day, a total of 12 hours apart.

So now that you’ve seen what a peak and positive result looks like, you can see a huge difference between the two.

Now not everyone will get a peak this dark or may get one darker. It’s all about your own body and how much LH it produces.

But the goal is to have your test line be darker than your control line.

What’s the Difference Between Peak and Positive?

The main difference in a peak and a positive result with ovulation prediction kits is whether you are having a surge in LH or your levels are rising/falling.

In the photo above that shows a peak and a positive result, the peak happened first, then I received those positives later that day, showing that my levels were dropping, but still high.

Some women may never receive a “peak” but get positives. Still, use those as clues that you are about to ovulate.

The reason you may not receive a peak can include:

  • Too much liquid prior to testing and your urine is diluted
  • Lower LH levels in general
  • Missed the actual surge

Sometimes a surge is a very short time (as short as 12 hours), so say you test at 12 pm today, and you get a negative result, but your surge begins around 10 pm, and ends 10 am the next day. If you test at noon again, you could miss that peak surge.

You would still get a positive result since your levels will just be coming down.

So if you are approaching what you think is your fertile window, I recommend testing a few times each day during that window.

My first-month using OPKs, I tested twice a day every day until I got my peak.

The tests shown above (Peak & Positive Results) were taken the same day, at 10 am, 3 pm, and then at 10 pm. So you can see that the change can happen quickly.

When Do I Start Using Them?

You’ll hear different advice on when to start using OPKs, but if you are new to them, I highly recommend starting early in your cycle.

When I first used them, I started right after my period.

The reason I suggest this is because if you are really unsure when you ovulate, you don’t want to start using them later in your cycle, and actually miss when you ovulated.

I’ve had months where I ovulated on day 9, so had I waited to test until day 11 or 12, I would have missed it completely. Plus, remember, you’ll receive a peak or positive 12-36 hour before ovulation. So my peak would have been on day 7/8.

If you test for a few months and know each cycle you don’t get a peak until day 20, then you can stop testing so early. But until you know what’s going on, it’s better to be safe than sorry.

I also recommend using them for the entirety of your cycle when you’re trying to conceive.

Sometimes our body will produce an LH surge, we’ll get a peak/positive result, but then the egg will fail to release.

When this happens, sometimes it will try again to release another egg, and you’ll get another peak LH, and hopefully ovulate.

This is just a precaution, especially if you are having trouble getting pregnant.

There are so many brands – how do I know which ones to buy?

There are SO many kinds out there. And of course, you want the kind that will give you the best result.

But higher cost does not always equal better quality.

For both my pregnancies, I ordered cheap kits on Amazon that came with both a pack of 40 LH strips and 20 HCG (pregnancy) tests.

The reason: I could use as many as I wanted without feeling bad, they were super inexpensive, and I liked reading the results myself.

You can also get name brand versions such as Clearblue Digital Ovulation Tests, where a smiley face will appear when you are having a surge.

It will come down to personal preference.

While the Clearblue will digitally tell you, as you can see from the above photos, it’s pretty clear when you get a peak or positive result with your own eyes, and can save you a lot of money.

Depending on the kind and amount of tests, the Clearblue will run you between $25-$40.

The cheap no-name brands will range from $9-$20 depending on how many LH and HCG strips come in each kit.

I personally have tried and had success with the following:

  • Easy@Home kit consisting of 50 LH tests and 20 HCG tests. I paid $16.50

With my first pregnancy, I got pregnant on the first try, and with my second, it took two cycles, both using OPKs.

It helped tremendously because my ovulation days change each cycle, making it difficult to track.

How Do I Keep Track of all My Results?

There are many ways to keep track of your daily results for comparison.

Some people tape each stick to a piece of lined paper, and time/date it to compare from day-to-day.

My favorite is the PreMom App. You take a photo of each test, and it saves it in a nice easy to view format. It will also then chart it for you in a graph to show changes.

It will also read the results and highlight when it recognizes a peak. I highly recommend this app. Oh, and it’s FREE. You can scan any brand into the app, not just Easy@Home.

OK, so I’m using OPKs, and just got my peak. Now what?

So now that you’ve gotten a peak, you’ll want to have sex the day of your peak, and the following two days. This will maximize your chances of conception, depending on when your egg actually releases.

Once you get a peak, keep testing as well. If your surge keeps going for a few days, keep having sex.

How Long Do I Have to Wait to Take a Pregnancy Test?

Oh, the dreaded two-week wait (TWW).

You’ll hear wait 14 days. But if you can wait at least 9-10 days, you’ll have a much better chance of seeing a result.

two-week wait until you can take a pregnancy test after using OPKs to find your fertile window.

I tested positive at 10 days past ovulation (DPO) for my first baby, and then I tested positive at 9 DPO with my second.

But if you don’t test positive then, DON’T PANIC. Everyone implants at different times and you don’t start producing HCG until a few days after implantation.

If you can hold out until 14 DPO, I truly applaud you. I am pretty sure I started testing around 5 DPO because I have no self-control. So if you are too, you are not alone.

The Downside to OPKs

While I am a big advocate for OPKs and their assistance in understanding when we ovulate, they do have some fallbacks.

As I’ve mentioned before, just because you have an LH surge, does not guarantee that you actually will ovulate.

For many reasons, when the egg attempts to release, it fails, and ovulation doesn’t occur.

When using OPKs, there is no way to determine if you actually released an egg or not. This is one reason I recommend continuing to test until either your period or a positive pregnancy test.

Another drawback is for women with PCOS or polycystic ovary syndrome.

Women with PCOS can have multiple LH surges, or higher levels for their entire cycle, making it difficult to determine ovulation and read the test results.

How Can I Confirm Ovulation?

OPKs are really great – but they work even better when paired with other methods to check for ovulation.

In addition to OPKs, you can also chart your basal body temperature (BBT) daily throughout your cycle.

When you get an LH surge, your temperature should rise for 3+ consecutive days. If your temperature does rise, then you did, in fact, release an egg.

If it drops or doesn’t increase during that LH surge, or immediately following, then you did not ovulate.

You will need to chart your temperature every day through your cycle to be able to get your baseline and see any changes.

Using OPKs and charting your BBT is a really great pairing in determining ovulation.

Give OPKs a Try

Ovulation Prediction Kits (OPKs) - How to Use Them and Everything You Need To Know

Since OPKs are fairly inexpensive, it’s worth a try. Especially if you’ve been trying for a while and are possibly missing your fertile window.

Start early in your cycle, test daily around the same time, try to avoid drinking for about 2 hours beforehand, and keep track of each test using the PreMom app.

The tests I recommend can be purchased on Amazon for less than $12 – ClinicalGuard Kit.

If you still have questions or feel I’ve left something out, drop it in the comments and I will gladly answer any other questions!


If you really want to get pregnant fast, check out this post –> The Ultimate Guide to Getting Pregnant

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