When Did I Conceive? 5 Pregnancy Calculators & Other Ways To Figure It Out

Even though almost all healthcare providers measure your pregnancy by the date of your last menstrual period (LMP) — because that’s the easiest and surest way to get a definite base start of a timeline — you might be wondering, “exactly when did I conceive” for your own purposes of tracking things. With all the cool technology out there these days, some women want to be able to start tracking their pregnancies and symptoms right away, even before getting an estimated due date from their doctors.

Knowing when you ovulated is pretty much a must if you want to know exactly when you conceived (give or take a day or two). So other than taking an ovulation test, how can you be sure? Most women have a period every 28 days, but that's just an average, according to Dr. Sherry Ross, OB-GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California. And Ross tells Romper that ovulation is when your egg is available to be fertilized within 24 to 36 hours, and it occurs approximately 14 days before you get your period. So when you’re using the following methods of calculating when you conceived, count back 14 days from when you were supposed to start your period — that’s a pretty good start to give you a general idea of when you ovulated and can help you determine a due date via app, planner, or website.

1Countdown To Pregnancy


Countdown to pregnancy is a pretty cool website you can use when you’re trying to conceive. There are “tools and tickers,” which give you a pregnancy test calculator of when the best time to test is, a due date calculator, an implantation calculator, an intercourse timing calculator, and most importantly, an ovulation calculator if you’re trying to figure out when you conceived.

There’s even an age and fertility chart, and a Chinese gender predictor if you’re into that sort of thing. You can also compare early pregnancy symptoms with other women who have the same cycle as you do, and see the percentages of women who had the same symptoms as you at the same time and had a positive (or negative) pregnancy test.

2First Response Website


Since First Response is pretty widely known for their ovulation predictor tests and their pregnancy tests, it makes sense they’d have an ovulation calculator and pregnancy due date calculator on their website. Though there’s not a whole lot of extras on their website (unless you’re looking for more information on their products or purchasing some tests), it’s a pretty clear cut way to figure out when you ovulated just by entering in the date of your last period and your average cycle length.

3Fertility/TTC Apps


Whether it’s Ovia, Glow, My Fertility Friend, or another TTC app, looking back at a fertility app that you used to get pregnant is a really easy way to see when you conceived. You used it to track when you were ovulating before, right? It makes sense you could use the same calendar to see when you had intercourse and count backwards from the day you were supposed to start your period to see when you ovulated. Or, you can just see where you marked you were ovulating when you were tracking. Pretty quick and easy, right?

4Period Tracker


Though some women use this app to track fertility to get pregnant, many women I know just use it to track their periods and to try to prevent pregnancy since the details are not as advanced as other fertility apps. However, if you happened to get pregnant while still using this app, Period Tracker makes it easy to calculate when you conceived by the calendar interface. Simply count back 14 days from the day when you were supposed to start your period.

5Your Own Personal Planner Or Calendar


Are you more of an old-school kinda gal who loves to decorate and use a planner you actually write in by hand? If you know your cycle and kept track of it via your planner before, simply count back 14 days from when you were supposed to start your period to see when you ovulated. That day is around the time when the sperm met the egg and the magic happened.

Remember, if you’re testing for ovulation with OPKs, once you have a positive ovulation test, you can drop your egg any time between 24 and 36 hours. And sperm can already be living inside you when it drops, so there may not be a 100 percent foolproof way to know exactly when your egg was fertilized. These apps and methods are just a fun way to get a really good estimate of when your new baby may have been conceived.

Check out Romper's new video series, Romper's Doula Diaries:

Check out the entire Romper's Doula Diaries series and other videos on Facebook and the Bustle app across Apple TV, Roku, and Amazon Fire TV.