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Pregnancy Due Date Calculator

Curious to Know Your
Estimated Due Date?


By Dr. Eleanor Hayes, MBBS, Obstetrician & Gynaecologist

Medically reviewed by Sarah (Registered Midwife)

Use our trusted, medically reviewed pregnancy due date calculator, aligned with current NHS guidance. Quickly estimate your baby’s expected arrival date, understand how it’s calculated, and access reliable advice throughout your pregnancy journey. 
Find your Due Date
LMP = Last Menstrual Period
Avg Length of Cycles ranges from: 22 to 44 days. 28 Days is the average for most women, leave at 28 days if unsure. This is not a diagnosis. The calculations that are provided are estimates based on averages.
Your Baby is Due:
AUG
04

Estimated Due Date: —

Week 04 · Trimester 1
0%

You are 0% of the way through your pregnancy!

* This is based on the cycle length provided, not an average cycle length of 28 days, however it is still an estimate.

What Does Your Estimated Due Date Mean?

Your estimated due date is the result given by our due date calculator, showing the likely date your baby will arrive.
This pregnancy calculator uses the first day of your last period or conception date, based on NHS guidelines.
While most pregnancies last 37–42 weeks, only a few babies arrive on the exact due date.​


The estimated date you receive helps plan appointments and scans, and your results may change after an ultrasound.
Always use your due date calculator as a guide, not a guarantee, and speak to your midwife for personalised advice.

Week-by-Week Pregnancy Timeline

Your estimated dates from the due date calculator give a week-by-week view of pregnancy milestones. The pregnancy calculator outlines key fetal development stages, while referencing screening periods and typical checks based on NHS guidelines. The NHS pregnancy calculator and related methods support planning for scans and appointments, use your pregnancy calculator results to stay prepared. 
First Trimester
(Weeks 1–12) 
  • Rapid development and the start of major organs
  • Dating scan recommended between weeks 8–14 (NHS milestone)
Second Trimester 

(Weeks 13–26) 
  • Baby's movements felt, bump grows
  • Whooping cough vaccine usually offered at weeks 16–32
  • Anomaly scan typically around week 20
Third Trimester 

(Weeks 27–40) 
  • Baby gains weight and grows
  • RSV vaccine may be offered from week 2
  • Additional midwife checks and birth planning

Your due date calculator supports understanding these steps, but always review the latest NHS milestones for updates. 

NHS Pathways and First Steps

After a positive pregnancy test, use the due date calculator or pregnancy calculator to estimate your baby’s arrival. Next, contact your NHS maternity service or a midwife to start care. You can often self-refer directly; there’s no need to see a GP unless you have ongoing health issues.


Your first midwife appointment uses your due date calculator estimate and covers medical history, and screenings. Be ready to share information from your pregnancy calculator results, and check NHS links for booking forms, appointment timelines,
and what to expect. 

Limitations of This Due Date Calculator

The due date calculator provides an estimate, not an exact prediction. Only around 4% of babies arrive on their calculated due date. Results from any NHS based pregnancy calculator or methods may be less accurate if you have irregular cycles, uncertain dates, or conceived by IVF.
Early ultrasound scans are often more precise than traditional due date calculator methods, your NHS team may update your dates after these appointments. Use the pregnancy calculator and NHS guidance as a planning tool, but always check with your midwife, as your real delivery date may vary by days or weeks.
What to Do Next 
 

After using the due date calculator or pregnancy calculator, follow these steps: 
  • Record your estimated due date for future reference and check it with your midwife at your first appointment. 
  • Contact your local maternity service or self-refer to a midwife soon after finding out you are pregnant.
  • Collect your medical history, current medications, and details to bring to your booking appointment.
  • Review recommended screening and scan dates using your due date calculator result. 
  • Track appointment dates and milestones in a pregnancy journal or planner.
  • Update your estimated dates in the pregnancy calculator if there are changes (e.g., after an ultrasound). 
  • Ask your midwife or GP about additional care if your cycle is irregular or if IVF conception applies.
These steps ensure your due date calculator result is used effectively for appointment planning and personalised pregnancy care.
Week-by-Week Pregnancy Milestones Table  
 

Week
Milestone/Check
Weeks 8-12
First appointment, due date calculator review, blood tests, early scan 
Week 16
Routine check, fetal growth, discuss vaccinations 
Week 20
Pregnancy calculator estimate reviewed, anomaly scan (detailed ultrasound) 
Week 25
Health check, discuss any symptoms and plans 
Week 28
Blood tests (anaemia, glucose), routine check; vaccinations offered 
Week 31
Growth check, review of baby’s movements and results 
Week 34
Health and birth planning, mental wellbeing review 
Week 36

Physical examination, position/birth options, symptom discussion 

Week 40+

Post-due date planning, induction options, further scans if needed 

Frequently Asked Questions

Still have questions?
Can’t find your answer? Email us and we’ll get back to you as soon as possible!
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The due date calculator provides an estimated date, only about 4% of babies are born on that specific day, so use it as a guide.
Yes, early scans often provide a more accurate date than the pregnancy calculator alone, and your NHS team may update your details
If you conceived through IVF, your NHS team and due date calculator will use the date of embryo transfer for best accuracy.
Speak to your midwife; an ultrasound can help confirm your stage.  
Accuracy relies on entering correct dates; for best results, combine the pregnancy calculator tool with clinical scans. 
Irregular cycles may affect estimates, use the due date calculator and ask your midwife about NHS scans for extra precision.
The date may change based on early scans, cycle length, or IVF details, so update your pregnancy calculator information as care continues.
Check NHS websites or local maternity teams for contacts and resources.
Bring information from your due date calculator, medical history, and details of any medications. Your team will review your pregnancy calculator results.
Take a test from the first day of a missed period, then use the pregnancy calculator and consult NHS advice for next steps.

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