- or -

Probability of Conception
on/by This Cycle


You have a probability of conceiving each cycle. The expected number of cyclesThe expected number is the mathematical term for the average value of a probability distribution. In this case, it corresponds to the average time to conception.

Given a sufficiently large enough group of individuals trying to concieve with the given fertility rate, we would expect only half of the group to have conceived by the expected number of cycles.
until conception is .

Chances of Conceiving by...


Concerned about your fertility?

It's natural to wonder if something might be wrong, especially if you don't conceive right away. No matter how long it's taking you to conceive, you are not alone.
We estimate each year individuals in the same age group will have not conceived after cycles as a result of random chance, and not because any underlying infertility issues.

About the Time to Conception Estimator

How long will it take you to conceive? Some of us go into family planning with an unrealistic expectation of how easy it is to conceive each cycle. Others fret that they'll be one of the unlucky few who is can't conceive without reproductive assistance, even before they start trying. And then there are those of us (myself included) are a simultaneously guilty of both.

The good news is that while the odds of conceiving any one cycle may be low, most people will be able to conceive in just a few cycles. The Time To Conception Estimator estimates your fertility rate based on your age, and then extrapolates to find the probability of conception within a year, as well as the expected number of cycles to conceive.

This website is intended to give us a little reassurance and help manage our expectations. Even if it's taking longer than you like to conceive, there is still a good chance that there may be nothing wrong. This website is not intended to be taken as medial advice. We are statisticians, not medical doctors. If you suspect a problem, please consult your medical professional.

Our modal uses the generally accepted, though rarely cited, probability of conception based on age (25% for those under 25, 20% for 25-30, 15% for 30-35, and 10% for 35-40). We note, however, that the chances of conception can significantly increase with optimal timing and frequency. [1] found couples who had intercourse ever two or every three days had a 35% chance of conception for those 16-26, and 20% for those 35-39. Even within an age group fertility rates can differ wildly [3]. Thus we give you the option to manually estimate your fertility rate. For a good overview on how timing of intercourse, and other factors, can affect conception we recommend [2].

To estimate the number of individuals of average fertility who do not conceive in cycles, we first estimate the number of people trying to conceive with average fertility in the specified age bracket. We start with the number of births for the age group, and remove an estimated percentage of people who may have needed fertility help, based on the assumed infertility rate for the age group [1]. We purposely over estimate the number of assumed couples with fertility assistance. As a result, we are under estimating the number of others who failed to conceive as a result of random chance. Thus, no matter how long it is taking to conceive your child, you can be assured you are not alone!

Ready for the next step? Once you become pregnant it's normal to worry about the possibility of miscarriage. Let us Reassure You, the odds of miscarriage are low. You can see the daily odds of miscarriage in our miscarriage chart. Our week by week calculator can show you when your little one's heart will start beating, and when you might feel the those first flutters.