Conception Date Calculator
Work backwards from a due date to when you conceived.
Your result
Conception usually occurs around 2 weeks after the last period started in a 28-day cycle. Sperm can survive up to five days.
Medical disclaimer: This tool is for education and is not medical advice. Read more.
Search by intent
Find this tool when you want to:
Learn more
How Pregnancy Due Dates Are Calculated
Naegele’s rule, ultrasound dating and why only 4 percent of babies arrive on the day.
Pregnancy & FamilyOvulation and the Fertile Window
Timing intercourse in the six days before and on ovulation boosts chances.
Pregnancy & FamilyHealthy Weight Gain During Pregnancy
How much to gain depends on your pre-pregnancy BMI.
Frequently asked questions
What does the Conception Date Calculator do?
Work backwards from a due date to when you conceived. Enter your values and the result and chart update instantly.
How accurate is it?
It uses published, widely used formulas. Results are estimates for education and planning, not a diagnosis. Talk to a qualified clinician about decisions affecting your health.
Is my information stored or shared?
No. All calculations run in your browser and nothing you type is sent to a server or saved.
What can I search to find this tool?
People find it by searching for: when did i conceive; conception date from due date; fertile window after birth.