The gender of a baby can typically be determined most reliably around 18 to 22 weeks of pregnancy through an anatomy scan ultrasound. However, there are earlier methods that can provide an indication of gender:

• The earliest ultrasound method, called the "nub theory," can be used from about 11 weeks, but has varying accuracy.
• Noninvasive Prenatal Testing (NIPT), a blood test done from around 9 to 10 weeks, can detect the baby’s sex with high accuracy.
• Some private or specialized ultrasounds may be done as early as 14 to 16 weeks with decent reliability, but the optimal time for visual gender confirmation is usually the 20-week anatomy scan.

Therefore, while the most common and reliable time to find out a baby's gender is at the 18-22 week ultrasound, it is possible to get indications from about 10-14 weeks with blood testing or early ultrasound techniques, though these might be less certain.