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Both calculators run independently — change the inputs on either side to compare results.

Pregnancy Weeks to Months Converter

Convert pregnancy weeks and days into months and identify your trimester, using either calendar months or four-week 'lunar' months — the two conventions that cause confusion.

Completed weeks of pregnancy (weeks)

Additional days (days)

Month convention

Pregnancy

Ovulation & Fertile Window Calculator

Pinpoint your likely ovulation day and fertile window from your cycle length, luteal phase, and the cycle day you're on today — based on the fixed-luteal-phase method.

Current cycle day (day 1 = first day of period) (day)

Average menstrual cycle length (days)

Luteal phase length (days)

Key differences

	Pregnancy Weeks to Months Converter	Ovulation & Fertile Window Calculator
Category	Pregnancy	Pregnancy
Inputs required	3	3
Result	Months and trimester	Days until ovulation (days)
What it does	Convert pregnancy weeks and days into months and identify your trimester, using either calendar months or four-week 'lunar' months — the two conventions that cause confusion.	Pinpoint your likely ovulation day and fertile window from your cycle length, luteal phase, and the cycle day you're on today — based on the fixed-luteal-phase method.