Pregnancy Calculator
Due date, current week, trimester and weekly milestones.
Estimates use Naegele’s rule (LMP + 280 days), adjusted for your cycle.
Monday, November 2, 2026
an ear of corn
Taste buds are forming and the inner ear is fully developed — baby may respond to your voice.
a rutabaga — Baby is gaining fat and skin is becoming less translucent.
This pregnancy calculator estimates your due date and shows exactly how far along you are. Enter the first day of your last menstrual period (LMP) and, optionally, your average cycle length. Using Naegele's rule (LMP plus 280 days, adjusted for your cycle) it works out your estimated due date, your current week and day, your trimester, and a week-by-week guide to your baby's growth — including a fruit-sized comparison and a note on what is developing each week.
How to use the pregnancy calculator
- Enter the first day of your last menstrual period in the date field.
- Adjust the cycle-length slider if your cycle is not the standard 28 days (it is clamped to a healthy 20–45 day range).
- Read your estimated due date and the coloured trimester badge showing your current week.
- Scroll the 40-week timeline and open “Week by week” to see every milestone from week 4 to week 40.
Frequently asked questions
How is my due date estimated?
We use Naegele's rule: 280 days (40 weeks) from the first day of your last period, adjusted by the difference between your cycle length and 28 days. It is an estimate — only about 1 in 20 babies arrive on the exact due date.
What if my cycle isn't 28 days?
Use the cycle-length slider. A longer cycle pushes the estimated due date later and a shorter cycle brings it earlier, because ovulation timing shifts accordingly.
How accurate is an LMP-based estimate?
It is a reliable starting point, but an early ultrasound dating scan is more precise, especially with irregular cycles. Always confirm with your midwife or doctor.
What does the trimester badge mean?
Pregnancy is split into three trimesters: weeks 1–13 (first), 14–27 (second) and 28–40 (third). The badge is colour-coded and updates as your week advances.
Is this a substitute for medical advice?
No. This tool is for general information and planning only. Always consult a qualified healthcare professional about your pregnancy.