How accurate is the due date?

It is an estimate; only about 4% of babies arrive exactly on their due date. Ultrasound dating in early pregnancy is more precise.

What if my cycle is not 28 days?

Enter your average cycle length — the due date shifts to reflect later or earlier ovulation.

Pregnancy Calculator

Estimate your due date, current week, trimester and baby size from your last period.

First day of last period

Cycle length (days)

Pre-pregnancy BMI

Week 10 · Trimester 1

Estimated due date

05 February 2027

Current week

10w 0d

Days remaining

209

Baby size

Strawberry

Conception (est.)

15 May 2026

Recommended weight gain

11,5–16 kg

Health disclaimer: This result is for general informational purposes only and is not medical advice. Individual health needs vary — consult a qualified healthcare professional before making health, diet, or medical decisions.

📐 About This Calculator

The estimated due date is 280 days (40 weeks) from the first day of your last menstrual period (Naegele’s rule), adjusted for cycle length. It also shows your current week, trimester and baby size.

Due date = LMP + 280 days (+ cycle adjustment) Conception ≈ LMP + 14 days Current week = ⌊days since LMP ÷ 7⌋ Trimester: 1 (<13w), 2 (13–26w), 3 (27w+)

Variable Definitions:

• LMP = First day of last menstrual period
• cycle = Average cycle length (default 28 days)

✅ Best used for:

• Estimating a due date
• Tracking pregnancy progress
• Planning prenatal milestones

⚠️ Limitations:

• An estimate only — ultrasound dating is more precise
• Assumes a regular cycle

📖 How the Due Date is Calculated

Naegele's rule

The classic estimate adds 280 days to the first day of your last period. A longer or shorter cycle shifts ovulation, so the calculator adjusts accordingly.

Trimesters and baby size

Pregnancy is grouped into three trimesters. Each week the calculator shows an everyday object roughly the size of your baby.

🔗 Related Calculators

Ovulation BMI Calorie / TDEE Date Difference