Sağlık
1

Pregnancy Calculator: Weeks, Trimester and Due Date

Calculate your pregnancy week, trimester, and estimated due date using your last period, conception date, or IVF embryo transfer date and cycle length.

Gebelik & Doğum Tarihi Hesaplama
ACOG / Naegele Kuralı

Haftalık gebelik takibi, tahmini doğum tarihi, bebek gelişimi ve kritik doktor kontrolleri

(Standart 28 gün)
Tahmini Doğum Tarihi
9 Haziran 2027 Çarşamba
Bebeğin Zodyak Burcu: İkizler
Mevcut Gebelik Haftası
10. Hafta 0 Gün
1. Trimester (Erken Dönem)
Kavuşmaya Kalan Süre
210 Gün
Tamamlanan: %25 (40 Haftalık Süreç)
Başlangıç (0. Hafta)10. Hafta (%25)Doğum (40. Hafta)

Bebeğiniz Şu An Bir Çilek Büyüklüğünde!

Meyve Benzetmesi
Çilek
Yaklaşık Boy
~3.1 cm
Yaklaşık Ağırlık
~4 gram

Tüm hayati organlar taslak olarak tamamlandı.

Önemli Tıbbi Kontroller & Tarama Takvimi

6 - 8. HaftaTamamlandı
İlk Muayene & Kalp Atışı

Kese ve embriyonun tespiti, ilk kalp atışlarının duyulması.

11 - 14. HaftaGelecek
İkili Tarama Testi

Ense kalınlığı (NT) ölçümü ve erken kromozomal tarama.

18 - 22. HaftaGelecek
Detaylı (2. Düzey) Ultrason

Organ taraması, fetal anatomi incelemesi ve cinsiyet teyidi.

24 - 28. HaftaGelecek
Şeker Yükleme Testi (OGTT)

Gestasyonel diyabet (gebelik şekeri) taraması.

32. HaftaGelecek
Yasal Doğum İzni Başlangıcı

SGK analık istirahat raporunun başlatılması veya çalışabilir onayı.

36 - 40. HaftaGelecek
NST ve Doğum Hazırlığı

Haftalık NST takibi, pelvik çatı kontrolü ve doğum planı.

Tıbbi Hatırlatma: Gebeliklerin yalnızca yaklaşık %5'i tam olarak hesaplanan tahmini doğum gününde gerçekleşir. Normal doğumların çoğu 37 ile 42. haftalar arasında meydana gelir. Takviminizdeki kesin haftayı doktorunuz ultrason ölçümüyle netleştirecektir.

Was this calculation tool helpful?
5.0(2 reviews)

Pregnancy Week and Estimated Due Date Calculation Guide

From the moment they learn they are pregnant, expectant mothers most often ask: "Exactly how many weeks pregnant am I now?" and "On what date is my baby expected to be born?" as their main questions.
In medical practice, pregnancy is counted in weeks and days from the first day of the last menstrual period (LMP) rather than fertilization. Although initially confusing, this is the globally accepted standard clinical method when the exact day of ovulation is difficult to identify.
HesapYap Pregnancy and Due Date Calculator; calculates your current pregnancy week, trimester, and estimated due date in seconds using your last menstrual period (LMP), conception date, or IVF embryo transfer date.

1. How Are Pregnancy Weeks and Due Dates Calculated?

Medically, a full-term human pregnancy is considered to average 40 weeks (280 days) in length.

Naegele's Rule (Traditional Calculation Method)

The formula described by German obstetrician Franz Naegele and used as a standard in maternity clinics is:

Tahmini Dog˘um Tarihi=(Son Adet Tarihinin I˙lk Gu¨nu¨+7 Gu¨n)−3 Ay+1 Yıl\text{Tahmini Doğum Tarihi} = (\text{Son Adet Tarihinin İlk Günü} + 7\text{ Gün}) - 3\text{ Ay} + 1\text{ Yıl}


Example: If the first day of your last menstrual period was 10 May 2026 :
  • 10 May + 7 Days = 17 May
  • 3 Months Back + 1 Year = 17 February 2027 (Estimated Due Date)
This formula assumes a regular 28-day menstrual cycle. If your cycle is longer than 28 days (for example, 32 days), the 4-day difference is added to the due date; if shorter, it is subtracted.

2. Calculations Based on Conception and IVF

A. When the Conception Date Is Known

The conception date can be used by women who track ovulation precisely or undergo insemination treatment. The biological interval from fertilization to birth is 38 weeks (266 days) in length:

Tahmini Dog˘um Tarihi=Do¨llenme Tarihi+266 Gu¨n\text{Tahmini Doğum Tarihi} = \text{Döllenme Tarihi} + 266\text{ Gün}



B. In IVF Pregnancies

Because the exact day a laboratory-fertilized embryo is transferred to the uterus is known, due dates in IVF pregnancies can be calculated much more accurately:
  • For a Day 3 Embryo Transfer: Transfer Date + 263 Days (or Transfer Date - 17 Days = Calculated LMP)
  • For a Day 5 Blastocyst Transfer: Transfer Date + 261 Days (or Transfer Date - 19 Days = Calculated LMP)

3. What Are the Trimesters?

Under American College of Obstetricians and Gynecologists (ACOG) standards, the 40-week pregnancy is divided into 3 main developmental stages (trimesters):
Stage
Week Range
Key Development and Medical Checks
1st Trimester
0w 0d – 13w 6d
Organ development (organogenesis), combined screening test, first ultrasound (CRL measurement)
2nd Trimester
14w 0d – 27w 6d
Detailed fetal ultrasound (weeks 20-22), feeling the baby's movements
3rd Trimester
28w 0d – 40w 6d+
Rapid weight gain, lung maturation, NST monitoring, birth position

4. When Does Birth Occur? (Term Classification)

The estimated due date (EDD - Estimated Due Date) does not mean the baby will necessarily be born that day. Statistically, only about 5% of babies are born on the exact calculated date. 90% of births occur in the broad window from 2 weeks before to 2 weeks after the estimated date.
ACOG clinical guidelines classify the week of birth as follows:
  • Preterm Birth: Births before the 37th week (36 weeks and 6 days).
  • Early Term: 37 weeks 0 days – 38 weeks 6 days.
  • Full Term: 39 weeks 0 days – 40 weeks 6 days (The ideal birth window with the fewest complications for the baby).
  • Late Term: 41 weeks 0 days – 41 weeks 6 days.
  • Postterm: 42 weeks 0 days and later.

5. Why Does Ultrasound Dating Differ from the Last Menstrual Period?

Many expectant mothers notice that the pregnancy week shown on ultrasound differs from the week calculated from their menstrual dates:
  • Ovulation may not happen on exactly day 14 each month; it can occur earlier or later.
  • Importance of First-Trimester Ultrasound: The baby's length measured on ultrasound, particularly between weeks 8 and 12 (CRL - Crown-Rump Length), is the most reliable gold standard for determining gestational age. If the LMP and first ultrasound differ by more than 5-7 days, your doctor may update your due date based on ultrasound measurements (ultrasound-adjusted LMP).

How to Use the Calculator

HesapYap Pregnancy and Due Date Calculator helps you create your calendar with these steps:
  1. Select Your Calculation Method: Last Menstrual Period (LMP), Conception Date or IVF (Day 3/5 Embryo Transfer) are the available options.
  1. Enter the Date and Your Cycle Length: Select the first day of your last period (specify if your cycle differs from 28 days).
  1. Review the Full Report: Instantly see your completed weeks and days, current trimester, estimated due date, and days remaining until birth.

Frequently Asked Questions

Why is conception placed at week 2 in a 40-week pregnancy? Because the pregnancy calendar starts on the first day of the last menstrual period. Ovulation and fertilization usually occur about 14 days later. Technically, when you conceive, the calendar already counts you as 2 weeks pregnant.
My cycles are very irregular. How can I know my due date? Mathematical formulas can be misleading with irregular cycles. In this case, your exact pregnancy week is determined using your obstetrician's ultrasound measurement (CRL) in the first 3 months.
Why can the estimated baby weight differ on ultrasound? Ultrasound devices combine head circumference (HC), abdominal circumference (AC), and femur length (FL) in a formula to estimate fetal weight (EFW). A physiological margin of error of around ±10-15% in these measurements is normal.

Legal and Medical Sources

Medical Notice: This content and calculator are intended for general information; they do not replace a personal clinical diagnosis or birth plan. Seek your obstetrician or the nearest emergency department immediately for vaginal bleeding, severe pelvic/abdominal pain, fluid leakage, vision changes, a sudden rise in blood pressure, or reduced baby movements.