Chances of getting Pregnant Calculator

Find your odds of conceiving below!

Chances of Getting pregnant Calculator

You’re here to find out what your specific chances are of getting pregnant. We built this calculator because we were fed up with reading we have a 20% chance per cycle of pregnancy which might be correct in very specific conditions; but isn’t representative for many who have been trying to conceive for a while or are a little older which is becoming more and more common.

How does the Chances of getting pregnant calculator work?


This was a product of the article we wrote on your chances of conceiving.

Many readers wanted a calculator to work out the chances. IT took a little bit longer to create than we would have liked, but the mathematics were fairly complex.

So in simple terms this is how the maths works. The image to the right show a normal distribution curve. Essentially anyone at the far left are completely barren and have a 0% chance of conceiving and those all the way to right are 100% fertility and are guaranteed to conceive on the next cycle. As you can imagine the majority of people fall somewhere in the middle with less and less people as you move to the extremes.

As we age and the longer we try the remaining people who haven’t already gotten pregnant are more likely to be to the left of the graph and as such it shifts to the left and more and more people are towards the 0% chance of conceiving – although this is still very unlikely.

Essentially most 20% quotes, don’t take this into consideration. 

For those more mathematically inclined or interested in how this works: Bayes’ theorem provides the formula for generating a posterior probability distribution from a prior distribution and an event which carries relevant information. In this case, the relevant event is that conception has not occurred. Firstly, an equation is developed which shows the chance of a couple not conceiving drawn from randomly distributed population after a certain number of cycles.

the mathematics of chances to get pregnant
With s(0) = 1 for any function of y
s(n) = chance of conception over number of cycles
n = number of cycles
P = probability of getting pregnant
y = This is the intrinsic conception rate, and this is unknown within a randomly drawn couple trying to conceive. To overcome this, let fn(y) be the distribution of the intrinsic conception rate conditional on n cycles of non-conception. Applying Bayes’ theorem for a continuous distribution we obtain the equation

Final equation for calculating the chance of getting pregnant

You can then use these to work out the chance of conception within a specified number of cycles and the chace of conception of future cycles (mathematically known as the posterior distribution after any specified number of non-conceptual cycles)

How accurate is the caclulator? 

Like any calculation it is only as accurate as the calculation and the asusmptions used. It is much more accurate than the 20% blanket terms and calculators that don’t take age, conception into consideration. Furthermore most of those chances of getting pregnant calculators don’t take into consideration the increasing chance that the older you are and the longer you have been trying means you have an ever increasing chance of having infertility or sub-fertility. This one does. Whilst it’s not perfect, it’s a model and is restricted by current information accuracy in terms of infertility and fertility. 

We will continue to update and improve it as more information comes to light.

What do we want to do in the future?

We will be looking through research and computaitonal and mathematical litrature to see what improvements we can make – there are 2 areas we would like to explore

  • Is a way for us to intergrate specific diagnosed infertility and sub fertility conditions into the calculation – At present we haven’t been able to find significant research to allow us to build an accurate moderfier to the data
  • Lifestyle impacts – I.E. Evidence based area’s that are known to impact sperm quality, egg quality or cervical mucus quality and have a calculatable value to improved chance of conceiving. – This one is even harder to build a specific modifier in the equation for.

If any mathematicians/Clinicians or general readers have any ideas, thoughts, links that may support us in developing these improvements please get in touch in the comments or email us at

Finally if you found this Pregnancy odds calculator helpful then please share it or pin it using an image below.