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Reverse Due Date Calculator Sign

Reverse Due Date Calculator

This extremely popular conception date calculator will calculate what date and day of the week your baby was conceived on based on your pregnancy due date. Also includes estimated dates for the missed menstrual period and for the range of days the pregnancy-causing "event" likely occurred within. Plus, you can also select any birth date -- meaning you can calculate conception dates for yourself and others.

Learn More

Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None
Month:Birth month:Month of birth:Pregnancy due month (or birth month):

Pregnancy due month:

Select the month of your baby's birth due date. Note that you can also select any date of birth to calculate when you or someone else was most likely conceived.

Day:Birth day:Day of due date:Pregnancy due day (or birth day):

Pregnancy due day:

Select the day of the month of your baby's birth due date. Note that you can also select any date of birth to calculate when you or someone else was most likely conceived.

Year:Birth year:Year of due date:Pregnancy due year (or birth year):

Pregnancy due year:

Select the year of your baby's birth due date. Note that you can also select any date of birth to calculate when you or someone else was most likely conceived.

Date:Conceive date:Conception date:Estimated date of conception:

Conception date:

This is 266 days subtracted from the selected pregnancy due date (the average per Naegele's Rule).

Period:Last period:Last period date:Estimated last period date:

Last period date:

This is 14 days prior to the conception date (assuming ovulation occurred on day 14 of your menstrual cycle).

If you would like to save the current entries to the secure database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

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Tip

Get the App!

$0.99, iPhone or Android.

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QR Code for Conception Date Calculator App
Help and Tools

Help and Tools:

This section contains the following help and tools tabs (content too long to fit within bordered frame can be scrolled up and down):

About: Click this tab for an introduction to the calculator.

Instructions: Click this tab for step-by-step instructions for using the calculator.

Terms: Click this tab for a list of the descriptions that are located within each popup help button (info icons).

PCalc: Click this tab for a handy "pocket" calculator you can use when you need to calculate an entry needed for the calculator.

Data: Click this tab to save a set of entries or a note in between visits. Note that notes and entries will be stored to your web browser's local storage (if supported by your browser of choice), meaning they can only be recalled with the same device and web browser you were using when you saved them. If you'd like to save data between devices you will need to subscribe to the Ad-Free Member Version.

 

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