While the Mother&Baby ovulation calculator can work out when you're ovulating based on your last period, ovulation tests detect your most fertile window by using your urine or saliva. Brands like Clearblue lead the way on the market, with easy-to-use test kits that are able to identify four or more fertile days to help you boost your chances of getting pregnant.
Ovulation prediction kits (commonly referred to as an OPK) mainly come in the form of urine tests, but saliva test kits are also available (although sometimes less effective). Here's everything you need to know about how ovulation prediction kits work and which brands are the best value for money.
Read more about what ovulation actually means here.
Our shortlist of the best ovulation test strips and kits
- Best for clear display: Clearblue Advanced Digital Ovulation Test Kit
- Best for super-quick results: Boots Ovulation Test Kit
- Best urine-based kit with large test quantity: Femometer Ovulation Test Strips Kit
- Best saliva-based kit: Fairhaven Health Fertile-Focus Ovulation Microscope
- Best budget test strips: 30 x One Step Ovulation Strips
- Best app-based kit: Clearblue Ovulation Test - Connected
How much do they cost and which brands are best?
Standard urine-based OPKs are priced between £10 and £15 per cycle. Most brands offer the same level of reliability, so definitely pick the one that offers you the most tests for the least amount of money.
Salivary ferning OPKs can be better valued. After the initial cost of between £20 to £35 for the microscope, you should be able to use it again and again. However, if it takes you a long time to conceive, you might have to replace it after about two years.
The best ovulation test strips and kits
Best ovulation test kit for clear display
This pack comes with the option of 10 or 20 ovulation tests. These tests promise to accurately track your levels of two essential fertility hormones (estrogen and luteinizing hormone) and to identify additional high fertility days that no other test can. With a smiley face display, you can be unmistakably clear in your peak fertility days.
Review: "I have used the clear blue sticks before but never the advanced. I had read reviews that it really did help but couldn’t see what the difference would be. Well I fell pregnant the first month! Can’t believe it - it was super accurate, easy to use (read instructions carefully). I tested first thing in the morning from day 8 and just found out we are pregnant - so I can’t give a better review! It works."
Type: Urine-based OPK
Number of tests: 10 or pack of 20
Best ovulation test kit for super quick results
Boots Pharmaceuticals Ovulation test allows you to identify your ovulation days by detecting the sharp rise, or surge, in the level of luteinising hormone that occur 24-48 hours before ovulation. Read like a pregnancy test, this kit of 20 tests is over 99 per cent accurate and you can expect fast results in just 3 minutes.
Type: Urine-based OPK
Number of tests: 20
Best urine-based ovulation kit with large test quantity
This is an excellent asset for predicting most fertile days. This product comes with 50 strips and with an app that you can use to track your daily tests. You just need to take a picture of your strip result, and the app will help you to keep track of your ovulation status.
Review: "This has really helped me track when I’m ovulating. My Ovia app was telling me I was ovulating a week later then I actually am. So I’m glad I bought these to check. I have used others in the past that haven’t worked as well. These are great with the app as it takes the guesswork out of them."
Type: Urine-based OPK
Number of tests: 50
Best saliva-based ovulation kit
Fertile-Focus is a personal ovulation microscope that claims 98 per cent accuracy. It works off patterns present in your saliva due to hormonal changes. Simply place a drop of saliva on the lens and read the pattern. This handy kit is accurate, easy-to-use and reusable which will save you money in the long run.
Review: "It is very convenient to use, simple and informative. And you don't have to constantly spend money on tests..."
Type: Saliva-based OPK
Number of tests: Unlimited
Best budget ovulation test strips
With 30 strips in this set, they are wider than most and so are easier to read (which is great when you're perching on the loo). A positive result test line may be observed within 1 minute. However, to confirm negative results, the complete reaction time of 10 minutes is required. They work to an accuracy level of 99 per cent.
Review: "I’ve used the expensive clear blue ovulation tests along with these and swear by this method. Yes they are cheap and yes they are basic but they are very very accurate."
Type: Urine-based OPK
Number of tests: 30
Best app-based ovulation test kit
Meet the first and only test which tracks two key fertility hormones and connects to your phone via an app. Typically identifying four or more fertile days which gives you more opportunities to get pregnant, it's over 99 per cent accurate at detecting the LH surge. We love the easy to read results - the digital Clearblue smiley face will appear on your fertile days.
Review: "I took a while to take the plunge and get this because of the large price tag but it proved to be well worth the money. We had been trying for 4+ months without success and I had been relying on the cheap strip ovulation tests. This product indicated I was actually ovulating at different times. I got pregnant with the first use. Could not recommend more for those struggling to conceive. I am now 17 weeks gone!"
Type: Urine-based OPK
Number of tests: 25
Why are Ovulation Prediction Kits helpful?
Having sex consistently, a couple of times a week throughout your cycle, is the best way to increase your chances of pregnancy, but it is also extremely useful to be able to schedule sex when you know it is likely to make the most difference. This is where OPKs come in.
Couples with busy lives often find regular sex difficult and it can sometimes feel like a chore, especially for those who have been trying for a while with no success. While you could chart your monthly cycles using the temperature method (tracking your temperature for patterns to predict ovulation), taking an over-the-counter test is a quick, easy, and reliable way to predict when ovulation is likely to occur.
If you have irregular cycle length, then OPKs are particularly useful. The test allows you to pinpoint your fertile window throughout the length of your menstrual every month and plan to have sex accordingly. This can often make these times more special, as you know your chances are maximised, improving your relationship and reducing the stress often associated with trying for a baby.
How do ovulation tests work?
Urine-based ovulation tests are the most common, they detect the LH surge in your urine, which signals when you are about to start ovulating. This is detected one or two days before ovulation. While a small amount of LH (luteinising hormone) already exists in urine, the amount increases by two to five times in the few days before ovulation, which is how the test can reliably identify your most fertile window. During this window, you are most likely to conceive.
Salivary ferning kits are another type of OPK. These operate rather by monitoring the rise in your oestrogen levels both before and just after ovulation. You test your saliva with a tiny, portable microscope and if your oestrogen levels have risen, the salt content of your saliva increases.
When the salt dries, it crystallises into a fern-like pattern, letting you know that you are now in your ovulation window. If you are not in your fertile window, the saliva will just dry in shapeless lumps.
How do you use OPKs?
These are rather like pregnancy tests, simply wee on a stick and coloured bands will appear on the stick to indicate whether or not the LH surge is occurring. If you are using a digital OPK, they usually use symbols, such as a smiley face to let you know when you are on your most fertile days. Generally, you should try to collect your wee between 10am and 8pm. The recommended optimum time is between 2pm and 2.30pm.
It is recommended that you try to collect your wee at about the same time every day, for added consistency, but this is not absolutely crucial. A few more tips - don’t do the test as soon as you wake up, and try to reduce the amount of liquid you drink for about four hours before you do the test. Too much liquid could dilute your urine, which may make it more difficult to detect the LH increase.
Afterwards, read the test results within 10 minutes and throw the test away once you’ve read it, as sometimes faintly coloured bands start appearing sometime after, which can deceive you about the result.
Salivary Ferning OPKs
Using a salivary ferning OPK is easier, simply place some of your saliva on the slide, either using your finger or licking it. Do this first thing in the morning, before you’ve had anything to eat or drink. Make sure you don’t put too much saliva on it and that it is free of any air bubbles for the best result.
Then, you wait for the saliva to dry and use the microscope to see whether there is any ‘ferning’ or not. You can compare your slide with examples in the instructions to see whether you are ovulating or not that day. With both types of OPK, the best time to start testing is on day 11 of your cycle and you can carry on for six days. Our ovulation calculator will help you with that.
Is there anything else to be aware of when using OPKs?
Although over-the-counter drugs like paracetamol won’t affect the tests, those containing Human Chorionic Gonadotrophin (hCG) or LH can have an effect on your result. Equally, some fertility drugs can also affect the results, so make sure you check any medication before taking the test.
Urine-based LH tests are 99% accurate at detecting ovulation. Salivary ferning tests aren’t as accurate, as the process of ferning may happen at other times in your menstrual cycle, especially if you are taking fertility drugs. One thing to note is that if you have poor eyesight, salivary ferning kits may not be the best method to choose.
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