Nub Theory Predictor:
Boy or Girl?

Upload your 12 to 14 week ultrasound image and predict your baby's gender using the nub theory

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Easy Upload & Guidance
Simply upload your ultrasound image and follow our step-by-step guide to accurately draw the nub lines.
Instant Gender Prediction
Receive an immediate boy or girl prediction based on the nub theory analysis of your ultrasound.
Completely Free
Our nub theory gender prediction test is a simple do-it-yourself tool, accessible to everyone.

Frequently asked questions

The nub theory is a method used to predict a baby's gender based on the angle of the genital tubercle (or 'nub') in relation to the baby's spine in early ultrasound scans, typically between 11-14 weeks of pregnancy.

At 10 weeks, it's too soon to use the nub theory to determine your baby's gender. At this point in time, the genital tubercle, or the 'nub', isn't formed enough yet to provide the stark angle differences required to tell whether the baby is a boy or a girl. The nub looks very much the same in both sexes, so predictions are speculative at best. For the nub theory to apply, it's advisable to wait until at least 12 to 14 weeks, when the nub is more well-defined. So guessing at 10 weeks might be fun, but it's not a case for accurate results. If you are chomping at the bit to find out your baby's gender, then patience and waiting — potentially an earlier ultrasound would clarify, clearer info.

Yes, this website offers the nub theory predictor free of charge. It's a do-it-yourself tool that will guide you through the process entirely free. However, keep in mind that these predictions are for entertainment purposes and should not be considered as medical advice.

The accuracy of the nub theory varies, with some studies suggesting it can be up to 90% accurate when performed by experienced technicians. However, the accuracy greatly depends on how many weeks pregnant you are. Studies show that if you are below 12 weeks, the accuracy is just above 50%. In the 12th week, it rises to 75-79%, and at 13 weeks or more, it approaches nearly 100%. Therefore, the further along you are, but still under 14 weeks, the better the prediction. It's important to note that this method should be considered for fun rather than as a medical diagnosis.

The nub theory is typically applied during early pregnancy ultrasounds, usually between 11 and 14 weeks of gestation. This is when the genital tubercle is most visible and before it has clearly differentiated into male or female genitalia.

Generally, if the angle of the nub to the spine is greater than 30 degrees (pointing upwards), it suggests a boy. If the angle is less than 30 degrees (more parallel to the spine), it suggests a girl. However, these are not definitive indicators.

No, the nub theory should not replace medical gender determination methods. It's considered an informal method and is not as reliable as later ultrasounds or genetic testing. Always consult with your healthcare provider for accurate medical information.

Yes, several factors can affect accuracy, including the quality of the ultrasound image, the baby's position, the skill of the technician, and the exact gestational age. The theory is also less reliable before 11 weeks or after 14 weeks of pregnancy.

While some medical professionals may be aware of the nub theory, it is not widely recognized or used as a clinical method for gender determination. Most healthcare providers rely on more established and accurate methods for determining fetal sex.

The nub theory is considered more reliable than old wives' tales or myths about gender prediction. However, it is less accurate than medical methods like Non-Invasive Prenatal Testing (NIPT) or later ultrasounds that can directly visualize fetal genitalia.

No, you cannot always apply the nub theory. The nub is not always visible in ultrasound images, and in such cases, it is impossible to use the nub theory for gender prediction.

Knowledge Base

Explore our in-depth articles on the nub theory and early gender prediction.