Pregnancy Due Date Calculator

Estimate your pregnancy due date, track your current trimester timeline, calculate vital milestones, and discover your baby's current developmental stage and weekly size analogies. 100% private, client-side execution.

Calculation Parameters
SuMoTuWeThFrSa
28 days
20 days45 days
Weight Gain Estimator (IOM Guidelines)
kg
cm
PRE-PREGNANCY BMI 22.0 (Normal)
RECOMMENDED TOTAL GAIN 11.5 – 16.0 kg
EXPECTED RANGE FOR WEEK 1 0.0 – 0.9 kg
Your Progress & Due Date
ESTIMATED DUE DATE 1st Trimester
Calculating...
... days remaining
GESTATIONAL AGE PROGRESS 0% Complete
0 Weeks 0 Days
Trimester Progress Timeline
First Weeks 1–13 ...
Second Weeks 14–27 ...
Third Weeks 28–40 ...
FETAL COMPARISON & DEVELOPMENT
Week 1
🌱
Poppy Seed Size
Approx: 1 mm • < 1 g
Your pregnancy journey is in its initial phase. Development begins after ovulation and successful conception.
Pregnancy Milestones

How is your Pregnancy Due Date Calculated?

Most pregnancies last approximately 40 weeks (280 days) from the first day of your last menstrual period (LMP). In clinical practice, this is estimated using Naegele's Rule: adding seven days to the first day of your LMP, subtracting three months, and adding a year.

However, Naegele's rule assumes a standard 28-day menstrual cycle. For women with cycles that are shorter or longer, ovulation does not occur on Day 14. This calculator adjusts for your custom average cycle length: adding days if your cycle is longer than 28 days, or subtracting days if your cycle is shorter, ensuring a much more personalized and precise prediction of your due date.

Alternatively, if you know the exact date of conception (often tracked via ovulation predictors, basal body temperature, or assisted reproduction technologies like IVF), your due date is calculated by adding 38 weeks (266 days) directly to the conception date.

Understanding Your Pregnancy Trimesters

Human pregnancy is divided into three distinct phases called trimesters, marked by specific physical developments and metabolic shifts:

  • First Trimester (Weeks 1 to 13): Spans from the first day of your last period to the end of week 13. Critical organogenesis occurs here; the baby's heart, spinal cord, and brain structures begin to formulate.
  • Second Trimester (Weeks 14 to 27): Spans from week 14 to week 27. Often considered the most comfortable phase, as morning sickness fades. Quickening (feeling fetal movements) starts, and fetal structures are monitored via ultrasound scans.
  • Third Trimester (Weeks 28 to 40+): Spans from week 28 to birth. The baby grows rapidly, storing body fat and preparing its lungs and vascular systems for independent breathing and survival. Reaching Week 37 marks full-term status.