Pregnancy journey
Pregnancy Scan Calculator & Week-by-Week Guide
Find out how many weeks pregnant you are, your due date and when each scan can be booked, then explore your baby’s development from week 4 to week 40.
Our week-by-week content is being reviewed by our clinical team. It’s general information only and never replaces advice from your midwife or GP.
Example journey
12 weeks and 3 days
- Due date
- Enter yours
- Trimester
- First
- To go
- 193 days
This is an example. Enter your due date or last period to see your own dates.
Example week
Week 12: early discoveries
About the size of a lime
Your baby is fully formed and now needs to grow and mature. Reflexes are developing, and your baby can open and close their fingers.
- Fully formed, now growing
- Reflexes developing
You may notice: This is the last week of the first trimester. Many people share their news around now.
Scans and tests at week 12
Reassurance scan · 6–15 weeks
Dating Scan
- ✓ Reassurance scan to confirm pregnancy and heartbeat
- ✓ Gestational age and estimated due date
- ✓ Single or multiple pregnancy check
- ✓ Three black-and-white prints to take home
An elective private scan. It is not a diagnostic test and does not replace your NHS scans.
Reassurance scan · 6–15 weeks
Early Peek Reassurance Scan
- ✓ Confirmation of pregnancy and heartbeat
- ✓ Gestational age and estimated due date
- ✓ Ultrasound-based health check for mother and baby
- ✓ Three black-and-white prints to take home
An elective private scan. It is not a diagnostic test and does not replace your NHS scans.
Keepsake blood test · From 6 weeks
Early Gender Blood Test
- ✓ Single blood sample from mum
- ✓ Baby’s sex result
- ✓ Clear explanation of your result
An elective blood test to find out your baby’s sex.
Keepsake blood test · From 6 weeks
Double Discovery Package
- ✓ Early Gender Blood Test
- ✓ Early gender scan, booked at the right stage
- ✓ Guidance on next steps
An elective blood test to find out your baby’s sex.
Screening blood test · From 10 weeks
NIPT Blood Test
- ✓ Blood sample from mum
- ✓ Screening report
- ✓ Optional baby’s sex result
- ✓ Results in about 5 working days once the sample reaches the laboratory
A screening result is not a diagnosis; a higher-chance result needs further testing.
Planning your next scan
Elective scans are optional. These dates show when each one can be booked in the example above.
- Dating Scan£75Book
Available now · 6–15 weeks
- Early Peek Reassurance Scan£80Book
Available now · 6–15 weeks
- Early Gender Blood Test£125Book
Available now · From 6 weeks
- Double Discovery Package£154Enquire
Available now · From 6 weeks
- NIPT Blood TestFrom £295Book
Available now · From 10 weeks
- Early Surprise Gender Scan£80Book
Coming up · 15–35 weeks
- Guardian Angel Anomaly Scan£125Book
Coming up · 18–21 weeks
- Little Pumpkin 4D Scan£95Book
Coming up · 20–34 weeks
- Mama’s Joyful Moments 4D Package£145Book
Coming up · 20–34 weeks
- Love’s Full Circle 4D Package£180Book
Coming up · 20–34 weeks
- Heartfelt Journey 4D Package£195Book
Coming up · Two sessions, 20–34 weeks
- Position & Presentation Scan£75Book
Coming up · 22–40 weeks
- Growth & Presentation Scan£85Book
Coming up · 22–40 weeks
- 10 Week Scan£135
Window passed · 10–11 weeks
How we calculate your dates
Your due date is estimated as 280 days (40 weeks) from the first day of your last period. This assumes a 28-day cycle; if your cycles are longer or shorter, or you’re unsure of your dates, a dating scan gives a more accurate due date. If your midwife has given you a due date from a scan, enter that instead.
Everything is worked out in your browser. Your dates are never sent to us, and they’re only saved on your device if you tick “Remember”.
When to get help straight away
This tool is for general information and planning only. Contact your maternity unit, call NHS 111 or, in an emergency, call 999 if you have:
- Bleeding from the vagina
- Severe or ongoing tummy pain
- Your baby moving less than usual
- Fluid leaking from the vagina
- Sudden swelling of the face, hands or feet, severe headache or problems with your vision
- A high temperature, or you feel very unwell
Elective private scans are optional. They’re a reassurance or keepsake experience and don’t replace the scans and care offered by your NHS maternity team.
Frequently asked questions
How accurate is a due date calculator?
It gives a good estimate, but only around 1 in 20 babies arrives on their due date. A dating scan in early pregnancy gives the most accurate due date.
How many weeks pregnant am I?
Pregnancy is counted from the first day of your last period, so at the time you conceive you’re usually already about 2 weeks pregnant. Enter that date above to see your weeks and days.
Which scans can I have at 12 weeks?
At 12 weeks you can book our Dating Scan or Early Peek Reassurance Scan (6–15 weeks). NIPT is also available from 10 weeks.
Ready to see your baby?
Book a pregnancy scan at our Croydon clinic, or call us to help you choose.