Frequently Asked Questions about the Clearblue Ovulation Test

Before you can be sure when to start testing, you need to determine your usual cycle length. The length of your cycle is the number of days from the day your period starts (Day 1) to the day before your next period starts.

Click here to figure out on which day of your cycle you should start testing.

The length of the cycle can vary from one woman to another, and can vary from cycle to cycle in the same woman.

To make sure that the hormone level in your urine is concentrated enough for the test to detect, it’s important not to urinate for at least 4 hours before doing the test.

You can test at any time of the day, but it should be at the same time each day. Many women find that first thing in the morning is the most convenient.

The Clearblue Ovulation Test helps you to pinpoint the 2 fertile days in your cycle by identifying a sudden surge in Luteinizing Hormone (LH) in your body with a simple urine test. LH is the hormone that triggers the release of an egg from your ovary. This release – ovulation – usually occurs approximately 24 to 36 hours after the LH surge.

If you use it each day on the days around the time in your cycle when you expect the LH surge, you can predict the 2 days each cycle when you are most fertile and therefore most likely to get pregnant.

The time when you are most fertile is on the day the LH surge is detected and the day after. You are most likely to get pregnant if you have sex on these days. Clearblue Ovulation Tests detect this LH surge, and therefore maximize your chances of conceiving.

Clearblue Ovulation Tests are 99% accurate in detecting the LH surge before ovulation.

Please note: these are abbreviated instructions. Always read the in-pack leaflet before carrying out a test.

Clearblue Ovulation Tests are very easy to use. When you’re ready to take a Clearblue Ovulation Test, open the foil wrapper by tearing along the slit. Remove the test stick and take off the cap.

Hold the Absorbent Sampler pointing downwards in your urine stream for 5 seconds only. Alternatively, you can collect a sample of your urine in a clean, dry container and hold just the Absorbent Sampler in the urine for 20 seconds only. When you remove it, remember to keep the Absorbent Sampler pointing downwards or lie the stick on a flat surface in front of you.

A Reference Line will appear to indicate that you have performed the test correctly.

After 3 minutes you will be able to read your result by comparing the strength of the colour of the Surge Line (the line nearest the arrow) with the Reference Line. To get an accurate reading, you need to read your result within 10 minutes of doing a test, and disregard any changes after this time.

If there is no Surge Line or the Surge Line is lighter than the Reference Line, you haven’t detected your LH surge. You should test again tomorrow at the same time using a new test stick.

If the Surge Line is similar to the Reference Line, or even darker, you’ve detected your LH surge, which means you’ve reached your most fertile time. Having sex any time in the next 48 hours will maximize your chances of getting pregnant.


Once you’ve detected your surge, there’s no need to carry on testing during that cycle. You can store any test sticks you have left in case you need them for your next cycle.

A Reference Line will appear to indicate that you have performed the test correctly.

After 3 minutes you will be able to read your result by comparing the strength of the colour of the Surge Line (the line nearest the arrow) with the Reference Line.

If there is no Surge Line or the Surge Line is lighter than the Reference Line, you haven’t detected your LH surge. You should test again tomorrow at the same time using a new test stick.

If the Surge Line is similar to the Reference Line, or even darker, you’ve detected your LH surge, which means you’ve reached your most fertile time. Having sex any time in the next 48 hours will maximize your chances of getting pregnant.

Your Clearblue Ovulation Test features a Reference Line (the line furthest from the arrow). If after 3 minutes you see a blue Reference Line, then the test has worked. Results must be read within 10 minutes of doing the test. Any changes after this time must be disregarded


If no lines appear in the result window this could be because too much or not enough urine was used. The best solution is to test again, carefully following the instructions, as soon as possible today (though you should wait 4 hours before passing urine again to ensure that the level of LH in your urine is not diluted). If you’ve collected a sample of urine in a clean, dry container, you can simply get a new test stick and hold just the Absorbent Sampler in the urine for 20 seconds.