Fertility calculator

Estimating your odds of getting pregnant

I created this "how long until I get pregnant?!" calculator to give a real, data-backed answer to a question that's genuinely hard to search your way to a straight answer on.

Just fill in your age, and the calculator estimates your odds of becoming pregnant within either 1 month or 1 year. Trust me, the odds are probably a lot better than you think!

The easy way to boost fertility

Did you know that one of the easiest ways to see huge gains in your fertility is by taking a daily prenatal vitamin -- even before you're pregnant? Read more about why.

My favorite might be the Smartypants Prenatal Daily Gummy (affiliate link) because it contains methylfolate and DHA Omega-3, both extremely important for fertility.

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And don't forget to stock up on my favorite, totally awesome pregnancy test: the First Response Rapid Test (affiliate link). It can tell you whether you're pregnant days ahead of other brands (read more about why).

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You vs. your friend

Now that I've either made you feel very relieved or incredibly panicked… let me tell you how this calculator works and what these numbers actually mean.

The odds generated from the calculator are based on averages taken from several scientific studies (see the references below). This means that while it's a great indicator of how likely the average person your age is to conceive, it's not personalized specifically to you. It may take you longer than the average couple, or you could get lucky and conceive on your very first try.

Most animals have a very high chance of conceiving, but we humans are somewhat lacking in our ability to get pregnant easily. Some of it comes down to plain bad luck, some to underlying fertility issues, and for others, optimizing fertility may be as simple as learning more about the fertile window.

Even when there's nothing wrong with your fertility, sometimes you just have bad luck. Here's what I mean: let's say you're a true fertile myrtle with a whopping 50% chance of getting pregnant every month (an unrealistically high number, but hear me out), and your friend has a more realistic 16.7% monthly chance.

To put it another way: you've been given a coin and need to toss heads, while your friend was given a die and needs to roll a six.

You: flip the coin, it lands on tails. Not pregnant.
Your friend: rolls a 6. Pregnant!

Although you had a higher likelihood of getting pregnant sooner, in the end, there's still some luck involved.

Your fertile window is shorter than you think

Only about 13% of women are able to predict the date of ovulation, and close to half of all women have trouble identifying their fertile window at all. You can only get pregnant on 5 to 6 days of your cycle -- that's it. So knowing exactly when you're in your fertile window matters enormously. If you don't have sex during that window, it's just not going to happen that cycle.

Fun fact: think you ovulate on day 14 of your cycle? Chances are, you don't -- less than 10% of women actually ovulate on day 14.

The one thing you should do to get pregnant faster

By far the most valuable thing you can do to increase your odds of conception is learning to recognize your most fertile days -- and the most reliable way to do that is with ovulation predictor kits (OPKs).

I'm not talking about the fancy digital ones. They're less sensitive and often don't work well for women with lower LH levels or PCOS. I'm talking about the simple paper strips that cost 10 or 20 cents apiece. I know what you're thinking -- you've tried them, they felt unreliable or confusing. They genuinely can work well, you just need to know how to use them correctly, which the manual usually doesn't explain well (a lot of women end up missing their fertile window by following the printed instructions literally).

To get started, all you need are some OPKs (LH test strips) -- one of my favorites is the Pregmate Ovulation Test Strips.

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Stuff for fellow data nerds

This fertility calculator is based on work by two groups of researchers. The odds of becoming pregnant in any given month, by age, were estimated from Johnson et al. (2012). To extrapolate these odds (the so-called intrinsic conception rate) to the 1-year mark, the method described in Sozou et al. (2012) was used.

A few assumptions worth knowing:

• This assumes 12 cycles in a year (roughly 12 30-day cycles). Longer cycles mean fewer chances to conceive in a year; shorter cycles mean a few extra shots.
• These are population averages, derived from many women. Most people in the general population don't have a diagnosed fertility issue, so if you do, your actual odds are likely lower than what's shown here.
• The model assumes no specific effort to time intercourse around ovulation. If you're tracking ovulation and timing things well, your real odds are probably better than the number shown.

That last point is good news -- your odds of conceiving could go up substantially just by knowing what to look for and what to do (more sex, better timing).

This tool gives a reasonable ballpark, not a diagnosis or a guarantee. There are many factors beyond age that come into play, and nothing here is medical advice.

References

1. Liu K, Case A; Society of Obstetricians and Gynaecologists of Canada. No. 269-Delayed Child-Bearing. J Obstet Gynaecol Can. 2012;34(1):80-93.
2. Sozou PD, Hartshorne GM. Time to Pregnancy: A Computational Method for Using the Duration of Non-Conception for Predicting Conception. PLoS ONE. 2012;7(10):e46544.
3. Wilcox AJ, Dunson D, Baird DD. The timing of the "fertile window" in the menstrual cycle: day specific estimates from a prospective study. BMJ. 2000;321(7271):1259-1262.
4. Zinaman M, Johnson S, Ellis J, Ledger W. Accuracy of perception of ovulation day in women trying to conceive. Curr Med Res Opin. 2012;28(5):749-754.