PREGNANCY
Convert clinician-confirmed pregnancy weeks and days into an everyday month and trimester estimate.
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FREE PREGNANCY WEEKS-TO-MONTHS CALCULATOR
Enter the completed pregnancy weeks and additional days given by your clinician to see an easy month and trimester estimate.
*The information submitted in this calculator is not stored.
Pregnancy care is recorded in weeksDoctors use completed weeks and days because months have different lengths. The month shown here is an everyday-language approximation.
Dating may change after an ultrasoundPregnancy is commonly counted from the first day of the last menstrual period, but an early ultrasound may provide a more appropriate estimated due date.
A HELPING HAND FOR WHAT COMES NEXT
Talk through the estimate with Aura, or keep it with your dates so it is easy to find next time.
Create a free ParentAura+ App account to keep this dated result, follow changes and build a clearer report over time.
Your result is still here. Please open ParentAura+ separately to continue.
WHAT YOUR ESTIMATE SHOWS
USEFUL TO KNOW
This is an estimation based on the details entered. Please consult your gynaecologist to confirm the outcome when it relates to your care.
UNDERSTANDING YOUR PREGNANCY TIMELINE
Pregnancy can sound confusing when one person says “20 weeks” and another says “five months.” Weeks are more precise, so that is the language your gynaecologist will usually use for appointments, scans and your estimated due date.
This is the standard medical way to date a pregnancy. Counting usually begins on the first day of your last menstrual period, approximately two weeks before conception in a typical cycle.
This refers to time since conception. Because the exact day of conception is often uncertain, it is usually about two weeks less than gestational age and is not the main dating method used in pregnancy care.
Calendar months are not exactly four weeks long, so there is no perfect weeks-to-months conversion. Use this chart for everyday conversation, but continue using your completed weeks and days for medical care.
| Completed pregnancy weeks | Approximate month | Trimester |
|---|---|---|
| 1–4 weeks | Month 1 | First |
| 5–8 weeks | Month 2 | First |
| 9–13 weeks | Month 3 | First |
| 14–17 weeks | Month 4 | Second |
| 18–22 weeks | Month 5 | Second |
| 23–27 weeks | Month 6 | Second |
| 28–31 weeks | Month 7 | Third |
| 32–35 weeks | Month 8 | Third |
| 36–40 weeks | Month 9 | Third |
| 41–42 weeks | More than 9 months | Third |
Early development happens quickly. Many people arrange their first antenatal visit during this period. Your clinician may confirm dates using your period history and an ultrasound.
The pregnancy continues to develop and routine care may include monitoring growth and discussing movements, scans and your health with your maternity-care team.
Appointments often become more frequent as birth approaches. Your care team monitors you and the baby and helps you prepare for labour and delivery.
An estimated due date is commonly calculated as 40 weeks, or 280 days, from the first day of the last menstrual period. An early ultrasound can lead your clinician to use a different date when it gives a more reliable estimate.
A due date provides an estimated pregnancy timeline. Clinicians use more specific language near the end of pregnancy:
Weeks and days give a more precise timeline for appointments, scans and milestones. Calendar months vary in length, so the month is best understood as an everyday approximation.
A pregnancy month is slightly longer than four weeks on average. This is why simply dividing the week number by four can make the month appear further ahead than expected.
Five months is approximately 18 to 22 completed weeks. Continue using your confirmed week-and-day count as the main pregnancy reference.
It converts completed pregnancy weeks and additional days into an approximate month and shows whether the date falls in the first, second or third trimester.
Yes. My Pregnancy Week Tracker shows your completed weeks, approximate month and trimester, while My Due Date & Pregnancy Timeline can keep your confirmed due date and important dates together in your private dashboard.
A HELPING HAND FOR FUTURE DATES
The matching ParentAura+ App keeps the dates and updates you choose to add together, so your own pattern becomes easier to follow over time.
FREQUENTLY ASKED QUESTIONS
No. Every calculator gives its result without asking for an account or contact details.
No. Your entries stay in the browser while you calculate and are not automatically added to a ParentAura profile.
You can leave with the result, talk it through with Aura, or explicitly save it to a free ParentAura+ Account for ongoing tracking.
No. Calculators provide mathematical estimates and general planning information. A qualified medical professional provides diagnosis and treatment.