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Pregnancy Due Date Calculator
Calculate your estimated due date using four standard methods — last menstrual period, conception date, IVF transfer or ultrasound measurement. See where you are in your pregnancy today, with key milestones and the dates of every major scan.
Your data stays in your browser. Sakina does not store any inputs.
How does the due date calculator work?
The standard obstetric formula assumes a 40-week pregnancy from the first day of your last menstrual period (LMP). In practice, only about 4% of babies arrive on their exact due date — most come within a two-week window around it. Our calculator uses the same math your midwife would use, with four input methods to match however you date your pregnancy.
From your last menstrual period (LMP)
Due date = LMP + 280 days, adjusted for cycle length. A 35-day cycle pushes the due date forward by one week; a 22-day cycle pulls it back six days.
From conception date
Due date = conception + 266 days. Most reliable if you tracked ovulation by basal body temperature or OPKs.
From IVF transfer
Day 3 transfer: due date = transfer + 263 days. Day 5 blastocyst: transfer + 261 days. Day 6: transfer + 260 days.
From ultrasound
Ultrasound in the first trimester is the most accurate dating method (\u00B1 3–5 days). We back-calculate the LMP from the measured gestational age, then apply the standard 280-day formula.
Frequently asked questions
How accurate is my due date?
Only about 4–5% of babies are born on their exact due date. Around 80% arrive within the 2 weeks around it (37–42 weeks). The due date is a best estimate, not a deadline.
What if my cycle isn’t 28 days?
Adjust the cycle-length slider — the calculator shifts the due date by the same number of days your cycle is above or below 28.
Why is pregnancy 40 weeks if my baby is only 38 weeks old?
Gestational age counts from the first day of your last period — about 2 weeks before conception. Foetal age counts from conception. Same baby, two different numbers.
Is the LMP or ultrasound method better?
Ultrasound between 8–14 weeks is the gold standard for accuracy. If your dates from LMP differ from ultrasound by more than 5 days in the first trimester, your midwife will typically switch to the ultrasound date.
Does the calculator store my data?
No. Every calculation happens in your browser. Sakina never stores the dates you enter.
Calculations based on standard obstetric formulas and WHO guidance. For medical decisions, always consult your doctor or midwife.