Baby Gender Prediction at 18 Weeks
At 18 weeks, most anatomical scan reports include a gender assessment. The genitalia are fully developed and clearly visible on a standard ultrasound, making this one of the most reliable windows for gender prediction.
Your Baby at 18 Weeks
- ✦Baby is about 140mm — the size of a sweet potato
- ✦Baby is now yawning, hiccupping, and rolling
- ✦The ears are in their final position and baby can hear clearly
Gender Prediction Methods at 18 Weeks
Nub Theory
Nub theory is no longer the primary method at 18 weeks — the genitalia are directly observable. Accuracy from a clear scan is around 90-95%.
Skull Theory
Skull theory gives around 80-85% accuracy at 18 weeks and is a good supplementary method.
Chinese Gender Calendar
The Chinese Gender Calendar can be checked alongside your scan for a cultural perspective — fun to compare but ultrasound results are far more reliable.
AI Ultrasound Analysis
Our AI achieves around 90-95% accuracy at 18 weeks by directly analysing the visible genitalia and combining with other anatomical markers.
Get Your AI Gender Prediction
Upload your 18-week scan — our AI analyses the clear gender markers visible at this stage for a highly accurate prediction.
Upload Your 18-Week Scan →Frequently Asked Questions
Can you tell the gender of a baby at 18 weeks?
Yes — 18 weeks is one of the most reliable times for gender prediction. Your anomaly scan at this stage often includes a gender assessment.
How accurate is gender prediction at 18 weeks?
Around 90-95% from direct ultrasound observation and AI analysis. This is close to the accuracy of a definitive anatomy scan.
What does a boy/girl look like on an ultrasound at 18 weeks?
At 18 weeks, the penis and scrotum are clearly visible in boys. In girls, the three white lines of the labia are typically visible — this 'hamburger sign' is one of the most reliable female gender indicators.