How to use the baby gender predictor
- Enter the mother's age at conception in years.
- Select the month of conception — roughly two weeks after the last period, not the month of the positive test.
- Press Calculate to see the chart's result.
This tool is entertainment. It has no scientific basis. If you want to actually know, an ultrasound or a prenatal blood test through your doctor is the answer.
Where the Chinese gender chart comes from
Said to date back centuries, the chart cross-references the mother's lunar age against the lunar month of conception. Studies examining its accuracy against real birth outcomes find it performs at approximately chance — about the same as a coin flip. It remains one of the most widely shared baby gender prediction methods online despite the lack of evidence behind it.
What actually determines a baby's sex
The mother's egg always carries an X chromosome. The father's sperm carries X or Y — X produces a girl (XX), Y produces a boy (XY). It's effectively a coin flip at conception, with a slight, consistent global skew toward boys (~105:100).
Old wives' tales you'll hear
- Bump shape reflects muscle tone and position, not sex.
- Fetal heart rate above 140 bpm = girl has been tested repeatedly and doesn't hold up.
- Morning sickness severity has at most a very weak association, too small to predict any individual pregnancy.
- The ring test swings from involuntary hand movements, not the baby.
How to actually find out
Ultrasound around 18–20 weeks usually identifies sex with Moderate accuracy. NIPT (a maternal blood test) can often determine it from around 10 weeks.[1] Amniocentesis/CVS are definitive but only performed for genuine medical indications. Ask your doctor which options are available to you, and check our due date calculator to see roughly when an anatomy scan would fall.
Sources
- American College of Obstetricians and Gynecologists — FAQs: Prenatal Genetic Screening Tests
Frequently asked questions
No. Studies find it performs at roughly chance level — comparable to guessing. It's a tradition, not a method.
No natural method has been shown to work. Sex is determined by which sperm fertilizes the egg, which is effectively random.
A prenatal blood test can often determine sex from around 10 weeks; ultrasound typically from 18 to 20 weeks.
With only two possible outcomes, any method is right about half the time. People remember the hits and forget the misses.
Slightly more boys are born globally — roughly 105 boys per 100 girls — a small, consistent and long-observed skew.