The Nub theory analyzes the angle of the genital tubercle (the "nub") visible in your ultrasound to guess your baby's sex. It is the most talked-about theory online, usually tried between 12 and 14 weeks. It is not scientifically proven, so treat it as a bit of fun.
The Nub theory (also called the "angle of the dangle") is one of the most popular methods for early gender prediction. It examines the genital tubercle — a small protrusion visible between the baby's legs in ultrasound images taken between 11-14 weeks.
The theory says this nub sits at a different angle depending on the baby's sex. Our reading estimates that angle against the spine. It can be wrong.
Submit your 11-14 week ultrasound where the genital tubercle is visible between the baby's legs.
We look for the genital tubercle in your ultrasound image.
We estimate the angle of the nub against the spine and make a guess from it.
Every report is checked by a real person before it's sent. You get the guess, a confidence level, and notes by email. For fun, not medical.
Want to see what nub theory is looking at before you order? Here are examples of the angle the reading uses:
The genital tubercle angles upward more than 30 degrees from the horizontal line of the baby's spine. This steeper angle is consistent with male development. At 12+ weeks, this sign becomes more pronounced and easier to read.
The genital tubercle lies parallel or slightly angled downward relative to the spine. A nub that points less than 10 degrees upward or runs parallel is typically associated with female development. The nub may also appear shorter.
These examples show the idea. A paid report also notes image quality, position, and weeks, and it includes a confidence level. Every reading is reviewed and approved by a real person. It is for fun, not as a diagnosis.
The Nub theory is based on how the genital tubercle develops differently in male and female fetuses:
Note: This theory is based on anecdotal observations and has not been scientifically validated.
Upload a scan from about 11-14 weeks for a written nub reading. For fun, not a medical result.
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Analyzes placenta position during early pregnancy. Most effective between 6-12 weeks for the earliest possible prediction.
Learn about Ramzi TheoryExamines cranial shape characteristics from ultrasound images. Best combined with Nub theory for a complete analysis.
Learn about Skull TheoryCommon questions about the Nub theory and gender prediction.
Medical Disclaimer: The Nub theory is based on anecdotal observations and has not been scientifically validated. Every reading is checked by a real person before it's sent, and is for entertainment purposes only. Always consult your healthcare provider.
While you wait for your next ultrasound, our free tools make it easy to follow your pregnancy week by week.
