Baby Gender Prediction at 12 Weeks
12 weeks is the sweet spot for early gender prediction. The nub is clearly angled, skull theory becomes applicable, and the combination of methods makes this one of the most popular weeks for early gender reveals.
Your Baby at 12 Weeks
- ✦Baby is about 53mm — the size of a lime
- ✦Reflexes are developing and baby can respond to touch
- ✦The digestive system is functioning and kidneys are producing urine
Gender Prediction Methods at 12 Weeks
Nub Theory
Nub theory is at its most readable at 12 weeks. The genital tubercle is clearly visible and the angle is usually definitive. A nub pointing up at 30+ degrees strongly suggests boy; horizontal suggests girl. Accuracy reaches ~75-80%.
Skull Theory
Skull theory becomes applicable at 12 weeks. A rounded skull with a more vertical forehead suggests girl; a more sloped forehead with a prominent brow ridge suggests boy. Accuracy is around 70%.
Chinese Gender Calendar
The Chinese Gender Calendar remains a popular supplementary method — many mums use it alongside nub and skull theory to build their prediction.
AI Ultrasound Analysis
AI analysis at 12 weeks combines nub angle, skull shape, and overall anatomy for around 80% accuracy. This is one of the best weeks for an early AI gender prediction.
Get Your AI Gender Prediction
Upload your 12-week scan — this is one of the best early windows for gender prediction and our AI will analyse the nub angle and skull shape for you.
Upload Your 12-Week Scan →Frequently Asked Questions
Can you tell the gender of a baby at 12 weeks?
Yes — 12 weeks is one of the best weeks for early gender prediction. Nub theory, skull theory, and AI analysis all become applicable, and combined accuracy reaches around 80%.
How accurate is gender prediction at 12 weeks?
Around 75-80% for nub theory, 70% for skull theory, and up to 80% for AI analysis that combines multiple markers. These figures improve as pregnancy progresses.
What does a boy/girl look like on an ultrasound at 12 weeks?
At 12 weeks, a boy's nub points upward at a noticeable angle while a girl's nub tends to run parallel to the spine. The skull also shows subtle shape differences — rounder and more vertical for girls, more sloped for boys.