Calculator of weeks of pregnancy

Find your pregnancy weeks and days on a chosen date, with a weekly date table.

Calculate from
Use the first day your last period started.
Enter your usual cycle length as a whole number from 20 to 45.
Pregnancy weeks and days
12 weeks 3 days
In your 13th week
On September 25, 2026
Estimated due date (EDD)Tuesday, April 6, 2027
Days until due date193 days to go
This is an estimate, not a medical assessment; confirm pregnancy dating and your due date with your clinician.
Defaults to today; choose another date to calculate your age on that day.
Pregnancy week-by-week dates
Completed weeksStart dateEnd dateMilestone
Week 0June 30, 2026July 6, 2026
Week 1July 7, 2026July 13, 2026
Week 2July 14, 2026July 20, 2026
Week 3July 21, 2026July 27, 2026
Week 4July 28, 2026August 3, 2026
Week 5August 4, 2026August 10, 2026
Week 6August 11, 2026August 17, 2026
Week 7August 18, 2026August 24, 2026
Week 8August 25, 2026August 31, 2026
Week 9September 1, 2026September 7, 2026
Week 10September 8, 2026September 14, 2026
Week 11September 15, 2026September 21, 2026
Week 12September 22, 2026September 28, 2026Week on your chosen date
Week 13September 29, 2026October 5, 2026
Week 14October 6, 2026October 12, 2026
Week 15October 13, 2026October 19, 2026
Week 16October 20, 2026October 26, 2026
Week 17October 27, 2026November 2, 2026
Week 18November 3, 2026November 9, 2026
Week 19November 10, 2026November 16, 2026
Week 20November 17, 2026November 23, 2026
Week 21November 24, 2026November 30, 2026
Week 22December 1, 2026December 7, 2026
Week 23December 8, 2026December 14, 2026
Week 24December 15, 2026December 21, 2026
Week 25December 22, 2026December 28, 2026
Week 26December 29, 2026January 4, 2027
Week 27January 5, 2027January 11, 2027
Week 28January 12, 2027January 18, 2027
Week 29January 19, 2027January 25, 2027
Week 30January 26, 2027February 1, 2027
Week 31February 2, 2027February 8, 2027
Week 32February 9, 2027February 15, 2027
Week 33February 16, 2027February 22, 2027
Week 34February 23, 2027March 1, 2027
Week 35March 2, 2027March 8, 2027
Week 36March 9, 2027March 15, 2027
Week 37March 16, 2027March 22, 2027Early term begins
Week 38March 23, 2027March 29, 2027
Week 39March 30, 2027April 5, 2027Full term begins
Week 40April 6, 2027April 12, 2027Estimated due date
Week 41April 13, 2027April 19, 2027Late term begins
Week 42April 20, 2027April 26, 2027Postterm begins

Focus on your estimated delivery date with the Due date of pregnancy calculator.

Calculation rules

Pregnancy age is the day difference between your chosen date and the cycle-adjusted last-period date, divided into completed weeks and remaining days.[P2][P5] An age of 12 weeks 3 days means you are in your 13th week.

The dating start is your last-period date plus cycle length minus 28 days, your due date minus 280 days, or your conception date minus 14 days.[P1][P2] The due date is 280 days after that start; accepted cycle lengths are 20–45 days and calculated ages are 0 weeks 0 days to 42 weeks 6 days.

Week N runs from the dating start plus 7 × N days through 6 days later. The table marks early term from 37 weeks, full term from 39 weeks, the estimated due date at 40 weeks, late term from 41 weeks and postterm from 42 weeks.[P8]

Frequently asked questions

Does 12 weeks 3 days mean the 12th or 13th week?
You have completed 12 weeks and 3 days, so you are in your 13th week; the table labels that row Week 12.
Can I calculate how many weeks pregnant I will be on another date?
Yes. Change Calculate pregnancy age on; the age, days remaining and highlighted week will follow that date within the calculator's supported range.
Why does pregnancy age include time before conception?
Gestational age uses a last-period dating convention, about two weeks before conception; it is not the elapsed time since fertilization.[P5]
Does the weekly table tell me when to arrange tests or delivery?
No. It shows calculated date ranges and term labels; confirm pregnancy dating and any care schedule with your clinician.

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Calculations run in your browser without sending your calculation inputs or results to the server. See “Privacy on this page” for information about access data.