Baby Gender Prediction at 20 Weeks
20 weeks is the standard anatomy scan milestone. At this stage, the sonographer will almost certainly confirm your baby's sex — and our AI can independently verify what the scan is showing.
Your Baby at 20 Weeks
- ✦Baby is about 160mm crown to rump — the size of a banana
- ✦Baby is swallowing amniotic fluid and practising digestion
- ✦The skin is starting to thicken as fat deposits develop
Gender Prediction Methods at 20 Weeks
Nub Theory
Direct genital observation is the method at 20 weeks — nub theory is historical at this point. Accuracy from a good scan image is ~95-99%.
Skull Theory
Skull theory provides a useful cross-check at 20 weeks with around 85% accuracy.
Chinese Gender Calendar
The Chinese Gender Calendar is most fun when you compare it against your definitive 20-week scan result — see how accurate it was for you!
AI Ultrasound Analysis
Our AI achieves ~95-98% accuracy at 20 weeks by analysing the clearly visible external genitalia alongside other anatomical markers.
Get Your AI Gender Prediction
Upload your 20-week anatomy scan — our AI will confirm what the sonographer sees and give you a second opinion with ~97% accuracy.
Upload Your 20-Week Scan →Frequently Asked Questions
Can you tell the gender of a baby at 20 weeks?
Yes — the 20-week anatomy scan is the gold standard for gender determination. In most cases, the sex is visible and confirmed at this appointment.
How accurate is gender prediction at 20 weeks?
Around 95-99% from direct observation and AI analysis at 20 weeks. This is as close to definitive as you can get before birth.
What does a boy/girl look like on an ultrasound at 20 weeks?
At 20 weeks, the penis, scrotum, and testes are clearly visible in boys — sometimes even the testes have descended. In girls, the labia and clitoris are clearly defined with the characteristic three-line 'hamburger' appearance.