You can usually find out a baby’s sex as early as 10 weeks with medical blood tests, and most people learn it at the 18–20 week ultrasound.

Earliest you can know

  • Non‑invasive prenatal testing (NIPT): A blood test that can identify fetal sex chromosomes from about 10 weeks of pregnancy, with accuracy often above 99% when a Y chromosome is present.
  • Specialized blood/gender tests: Some labs and commercial tests report sex from around 6–7 weeks by detecting fetal DNA in the mother’s blood, though quality and validation vary by provider.
  • Invasive diagnostic tests (CVS/amnio): Chorionic villus sampling at about 10–13 weeks and amniocentesis at 15–20 weeks can determine sex with very high accuracy, but are usually done only for medical/genetic reasons because they carry a small risk of complications.

Ultrasound timing

  • Early ultrasound: Genital structures start forming in the first trimester, but before about 14 weeks it is often too early or unreliable to tell sex, and “guesses” at 11–13 weeks can be wrong.
  • Standard anatomy scan: Most parents find out at the detailed ultrasound around 18–22 weeks, when the sex organs are usually visible and accuracy is commonly above 95%.

At‑home and non‑medical methods

  • At‑home blood tests: Some kits use a finger‑prick blood sample to look for fetal DNA and claim very high accuracy from around 6 weeks, but reliability depends on lab quality, contamination control, and proper timing.
  • Old‑wives’ tales & symptom “clues”: Methods based on cravings, bump shape, heart rate, or online “gender charts” are not scientifically reliable and should be treated as for fun only.

What doctors usually recommend

  • For most low‑risk pregnancies, the most common ways to learn sex are:
    • NIPT from 10 weeks if already indicated or offered in your setting.
* The 18–20 week anatomy ultrasound, where sex is checked incidentally while assessing overall development.

Always confirm timing and options with a healthcare professional, since guidelines and availability can differ by country and clinic.