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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

Conception Date Estimate Calculator

Estimate how many days ago conception likely occurred from your last menstrual period, corrected for your cycle length and luteal phase rather than assuming day-14 ovulation.

Days since first day of last period (LMP) (days)

Average menstrual cycle length (days)

Luteal phase length (days)

Key differences

	Pregnancy Weeks to Months Converter	Conception Date Estimate Calculator
Category	Pregnancy	Pregnancy
Inputs required	3	3
Result	Months and trimester	Days since estimated conception (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.	Estimate how many days ago conception likely occurred from your last menstrual period, corrected for your cycle length and luteal phase rather than assuming day-14 ovulation.