An ovulation test is a test that can help a woman know when her fertile days are, in order to conceive a baby.
Some tests measure the change in one hormone, others monitor the levels of two hormones.
My opinion is that they are useful for occasional use when you try to get pregnant and if you have a regular cycle (no more than 3 days shorter or longer every month) and no problems in getting pregnant (if you've been in the past), but not if you've tried a few months and haven't succeeded immediately, or if you don't want to waste months trying.
They used to sell them in packs of 7 sticks, now they sell them in packs of 10 or 20 sticks.
A test kit includes testing sticks that can help you spot the day you ovulate.
You wet one stick with your urine and after a few minutes it will show
you a symbol indicating whether there is an increase in the LH hormone (luteinising hormone) or in LH and estrogen, which happens about a
couple of days before ovulation. Those are your most fertile days, when you should have sex because you have the highest chance of conceiving.
The manufacters say the tests are very accurate in measuring the level of hormones. The ovulation test that measures two hormones is more accurate that the test that measures one hormone.
The problem I think here is that that you have to start doing the test on a specific day of your cycle and continue for a few days until you spot your ovulation day. But if you don't start on the right day, you may miss it because you ovulated before you started or because you ovulate later, or you'd have to test every single day. This can bocome quite expensive, they used to sell them in packs of 7 sticks, now they sell them in pack pof 10 or 20 sticks.
And the next month your cycle may change slightly.
Also, the one or the dual hormone test shows you only the 2/4 most fertile days, the day before the ovulation and the ovulation day, without much notice and you may not have the opportunity to have sex on those two days and think you have missed your chance for that month. However, there are more days when a woman can get pregnant.
So, these fertility tests are good if you have a very regular cycle and are not in a hurry to get pregnant. Anyway, for a more accurate "fertility predictor" or "fertility days calculator" I would use a fertility monitor.