How to use: Calculate your pregnancy timeline using the first day of your last menstrual period (LMP). Enter the LMP date using the date picker. Add your average menstrual cycle length in days (typically 28 days, but can range 21-35 days). The calculator shows your estimated due date (40 weeks from LMP), estimated conception date (about 2 weeks after LMP), and current weeks pregnant. This uses Naegele's Rule, the standard method used by healthcare providers. Remember that only 5% of babies arrive on their exact due date - it's an estimate, not a guarantee.

How to use: This calculator works backward from known dates to find conception date. Choose to calculate from either your due date (if your doctor provided one) or from your last menstrual period. Select the appropriate date in the date picker. The calculator shows estimated conception date (when fertilization likely occurred), estimated due date, weeks since conception, and current trimester (1st: weeks 1-12, 2nd: 13-27, 3rd: 28-40). Conception typically occurs during your fertile window, 11-21 days after your last period started. Useful for understanding pregnancy timeline or paternity timing.

How to use: Advanced due date calculator with comprehensive pregnancy milestones. Choose to calculate from either last menstrual period (LMP) or conception date. If using LMP, enter the first day of your last period and your average cycle length. If using conception date, enter the known conception date. The calculator provides complete pregnancy timeline: due date, conception date, last period date, current weeks pregnant, days until due date, and current trimester. Includes important milestones: first trimester end (week 13), second trimester end (week 27), and full term date (week 37 when baby is considered fully developed).