Estimated Due Date
—
40 completed gestational weeksCalculate your gestational week,
gently and accurately.
Calculate your exact gestational age and due date (EDD). Track your current week and day-by-day countdown.
CALCULATION RESULT
Your Pregnancy Timeline
16 Week
16 weeks + 0 days
of 40 obstetric weeksToday
You are currently in your
second trimester.
A blossoming energy phase. Fetal movements become noticeable and senses develop.
168 days until you meet your baby.
Estimated Conception
—
Probable fertilization windowFull Term (Week 37)
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Term pregnancy thresholdWhich Gestational Week Are You In?
Pregnancy week calculation determines gestational age from your last menstrual period (LMP), spanning 40 obstetric weeks (280 days).
The gestational wheel highlights the 3 trimesters: 1st (weeks 1–13), 2nd (14–27), and 3rd (28–40). Select any week to inspect progress.
Hover or tap on any week to explore gestational stages
Last Menstrual Period First day of your last cycle
Calculate Elapsed Days Days elapsed from LMP to today
Weeks + Days Result e.g., 24 weeks + 3 days
Calculate Gestational Week from Start Date
To calculate pregnancy weeks, divide elapsed days from your LMP by 7: the result gives weeks and the remainder gives days.
For example, 100 days equals 14 weeks + 2 days, placing you in the 15th week of pregnancy.
The calculator computes this automatically, personalized to your exact cycle length.
Pregnancy Weeks and Estimated Due Date
The estimated due date (EDD) adds 280 days (40 weeks) to your LMP using Naegele's standard obstetric rule.
Only 4–5% of births happen on the exact due date; most occur between weeks 37 and 42.
The Complete 40-Week Gestational Calendar
The pregnancy calendar maps all 40 weeks across 3 trimesters, highlighting key fetal milestones and maternal health.
1st Trimester (wks 1–13) 2nd Trimester (wks 14–27) 3rd Trimester (wks 28–40)
Click on any week number to reveal specific developmental milestones
Key Milestones of Fetal Development
Key clinical milestones tracked through routine check-ups and obstetric ultrasounds:
Weeks 4–5
Positive Pregnancy Test
Beta-hCG detection and secure embryo implantation into the uterine lining.
Weeks 6–8
First Audible Heartbeat
Ultrasound confirms embryonic heartbeat; the neural tube completes closure by week 6.
Weeks 11–13
First Trimester Dating Scan
CRL measurement for dating and Nuchal Translucency (NT) combined screening.
Weeks 18–22
Mid-Pregnancy Anatomy Scan
Detailed anatomy ultrasound evaluates fetal organs; first kicks are felt.
Weeks 24–28
Glucose Tolerance Screening
Glucose tolerance test (OGTT) for gestational diabetes; lungs produce surfactant.
Weeks 35–37
GBS Screening & Term Readiness
Group B Strep (GBS) swab performed; pregnancy reaches full term at 37 weeks.
Week 40
Estimated Due Date
Pregnancy reaches 40 weeks (280 days), with average birth weight around 3.3 kg.
Personalized Calculations for Variable Cycles
Calculations adjust to cycle length: a 32-day cycle shifts ovulation to day 18 because the luteal phase remains a steady 14 days.
Using the formula (cycle − 14 days), the calculator adjusts your estimated due date accurately for shorter or longer cycles.
Conception dating adds 266 days (38 weeks), ideal for IVF embryo transfer dates.
Menstrual Cycle Duration 28 days
Estimated Ovulation Day 14
Estimated Conception Day 14
Total Gestation Days 280 days
Come si calcolano le settimane
Il conteggio parte dal primo giorno dell'ultima mestruazione (LMP), secondo lo standard clinico OMS.
La Regola di Naegele utilizza questa data perché certa e documentabile rispetto al giorno esatto del concepimento.
L'età gestazionale si esprime in "settimane + giorni" (es. 14+2). Una gravidanza a termine dura 40 settimane (280 giorni).
Data di Riferimento (LMP)
Il punto zero è il primo giorno dell'ultimo ciclo mestruale, da cui si conteggiano 280 giorni.
Formula Matematica
I giorni trascorsi divisi per 7 indicano le settimane concluse; il resto esprime i giorni aggiuntivi.
Età Gestazionale vs Embrionale
L'età gestazionale precede l'età biologica del feto di circa 2 settimane (fase pre-ovulatoria).
Tabella settimane gravidanza
Consulta la tabella completa di corrispondenza tra trimestri, mesi solari e settimane gestazionali con le tappe di sviluppo ed esami medici principali.
| Trimestre | Mese | Settimane | Sviluppo Fetale & Controlli Medici |
|---|---|---|---|
| 1° Trimestre Settimane 1 – 13 | 1° Mese | Settimane 1 – 4 | Fecondazione dell'ovocita, formazione del blastocisto, impianto endometriale e test di gravidanza positivo. |
| 2° Mese | Settimane 5 – 8 | Chiusura del tubo neurale, comparsa dei primi abbozzi degli organi e rilevazione ecografica del battito cardiaco. | |
| 3° Mese | Settimane 9 – 13 | Passaggio da embrione a feto. Ecografia di datazione del 1° trimestre (misura CRL) e screening Translucenza Nucale (NT). | |
| 2° Trimestre Settimane 14 – 27 | 4° Mese | Settimane 14 – 17 | Differenziazione degli organi genitali, comparsa dei riflessi motori e primi movimenti fetali impercettibili. |
| 5° Mese | Settimane 18 – 22 | Ecografia Morfologica strutturale per lo studio completo dell'anatomia fetale; percezione nitida dei movimenti da parte della madre. | |
| 6° Mese | Settimane 23 – 27 | Sviluppo dell'udito e dei sensi, formazione delle papille gustative; curva da carico orale di glucosio (OGTT). | |
| 3° Trimestre Settimane 28 – 40+ | 7° Mese | Settimane 28 – 31 | Accrescimento ponderale rapido, produzione di surfactante polmonare; ecografia di accrescimento fetale del terzo trimestre. |
| 8° Mese | Settimane 32 – 35 | Posizionamento cefalico del bambino; accumulo di tessuto adiposo protettivo e controlli periodici della pressione arteriosa. | |
| 9° Mese | Settimane 36 – 40+ | Gravidanza a termine (a partire da 37+0). Tampone per Streptococco B (GBS), monitoraggi cardiotocografici (NST) e travaglio di parto. |
Frequently Asked Questions,
clear obstetric answers.
How can I know exactly which week of pregnancy I am in?
Pregnancy weeks are calculated from your LMP by dividing elapsed days by 7 (e.g., 14 weeks + 3 days). A first-trimester ultrasound CRL measurement provides clinical confirmation.
Which date is used to start counting gestational age?
Obstetric standards start counting from your last menstrual period (LMP) rather than conception, as menstruation provides a definite, measurable starting date.
How are days counted in addition to full weeks?
Gestational age is expressed in completed weeks plus days (+0 to +6): 12+4 means 12 full weeks plus 4 days into week 13.
Can I find my pregnancy week by entering my due date?
Yes. By selecting 'Due Date (EDD)' mode, the tool counts backward 280 days from your due date to determine your current week.
How do I know how many days and weeks remain until delivery?
The tool subtracts elapsed days from 280 (40 weeks), displaying the exact days and weeks remaining until your estimated due date.
How do pregnancy weeks convert into months?
A pregnancy month averages 4.3 weeks. Groupings align by trimester: Months 1–3 (weeks 1–13), Months 4–6 (weeks 14–27), and Months 7–9 (weeks 28–40). See our conversion table for details.
How do I identify which trimester I am in?
Pregnancy consists of 3 trimesters: First (weeks 1–13), Second (weeks 14–27), and Third (weeks 28–40+).
Is the date of the last menstrual period always required?
No. With irregular cycles or unknown LMP, use your ultrasound-estimated due date or IVF embryo transfer date.
Why might my calculated week differ from an ultrasound dating?
LMP dating assumes a 28-day cycle with day-14 ovulation. If ovulation occurred earlier or later, early ultrasound (CRL) adjusts your gestational age.
What does it mean to be at the 20th week of pregnancy?
Week 20 marks the pregnancy halfway mark. The fetus measures ~25 cm, movements are clearly felt, and the anatomy scan is performed.