Compare calculators

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

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)

Pregnancy

Gestational Age Calculator

Converts the number of days since your last menstrual period into gestational age expressed as weeks and days. Use it at any point in pregnancy to know your exact stage for prenatal care, screenings, and milestone tracking.

Days since Last Menstrual Period (days)

Key differences

	Ovulation & Fertile Window Calculator	Gestational Age Calculator
Category	Pregnancy	Pregnancy
Inputs required	3	1
Result	Days until ovulation (days)	Gestational age (weeks)
What it does	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.	Converts the number of days since your last menstrual period into gestational age expressed as weeks and days. Use it at any point in pregnancy to know your exact stage for prenatal care, screenings, and milestone tracking.