Chinese Gender Chart Accuracy: What the Evidence Actually Shows

The Chinese gender chart predicts baby sex at roughly 50 percent, which is chance. A 2010 population analysis of 2.8 million Swedish births concluded the chart performs no better than a coin flip. It is fun, not predictive.

How the chart is supposed to work

The Chinese gender chart cross-tabulates two inputs: the mother's age at conception and the lunar month of conception. Each cell on the chart shows "boy" or "girl". There is no biological mechanism claimed behind it. The chart is often described online as having Qing-Dynasty origins, but those origin stories are difficult to verify. You can see the actual chart and try it on our Chinese Gender Chart tool.

What the data actually says

The largest peer-reviewed test of the chart comes from a Swedish population study.

Villamor et al. (2010) cross-referenced the chart against 2,840,755 singleton births in Sweden between 1973 and 2006 (Swedish Medical Birth Register). The study reported a kappa statistic of 0.0002 (95% CI -0.0009 to 0.0014) between predicted and actual sex, statistically indistinguishable from chance. On a binary outcome, a kappa near zero means accuracy sits around 50 percent, the floor for any guess-based method.

There is no peer-reviewed study at comparable scale showing a materially different result. If anyone tells you the chart is "90 percent accurate," they are recalling anecdotes, not data.

Why it feels like it works

Three mental biases make the chart feel more predictive than it is. First, base-rate intuition: with only two possible outcomes, any chart that guesses "boy" consistently will be right roughly half the time, which matches the chart's observed accuracy. Second, confirmation bias: parents remember the correct guess and forget the incorrect one. Third, selection effects in anecdotes: people who want the chart to work are more likely to share a success story online, skewing the informal evidence you see.

When to use a real method

If knowing your baby's sex matters to you for medical or planning reasons, there are three evidence-based routes.

Non-invasive prenatal testing (NIPT) uses cell-free fetal DNA from a maternal blood sample, is usually available from 10 weeks, and can screen for sex chromosomes as part of aneuploidy screening (ACOG, Prenatal Genetic Screening Tests). It is typically ordered alongside tests for Down syndrome, Patau syndrome, and Edwards syndrome.

Mid-trimester anatomy scan at 18 to 22 weeks is the standard time when sex can usually be determined. Per ACOG's Ultrasound Exams FAQ, "if the fetus is in a good position, it may be possible to tell the sex." Accuracy varies with fetal position.

For dating questions that often come up in the same visit, see our due date vs. conception date guide, or use our Due Date Calculator.

Using the chart anyway

There is nothing wrong with using the chart for a baby shower game or a gender-reveal guess. Just do not make decisions based on it, and do not let a "prediction" change how you connect with your baby. The chart is a folk tool with a 50 percent hit rate, not a diagnostic.

FAQ

Is the Chinese gender chart scientifically accurate?

No. A 2010 Swedish population study of 2,840,755 singleton births (Villamor et al.) found the chart's agreement with actual sex was statistically indistinguishable from chance, kappa of 0.0002.

What percentage of predictions are correct?

About 50 percent on average. Because there are only two outcomes, any method with a kappa near zero sits at the chance floor of 50 percent. The Villamor study found the chart has no signal distinguishing it from random guessing.

How accurate is a 12-week ultrasound compared to the chart?

Both a first-trimester ultrasound and a 20-week anatomy scan are more reliable than the chart. ACOG's Ultrasound Exams FAQ notes that if the fetus is in a good position, sex can usually be determined at the anatomy scan; specific accuracy varies with position and operator.

Can NIPT tell sex earlier than an ultrasound?

Yes. NIPT uses a maternal blood sample and is available from about 10 weeks, typically ordered as part of aneuploidy screening per ACOG's Prenatal Genetic Screening Tests FAQ.

Where does the chart come from?

The chart is often described online as having Qing-Dynasty origins, but those origin stories are difficult to verify. It predicts sex from the mother's age at conception and the lunar conception month.

Bottom line

If you are using the Chinese gender chart as entertainment, the only real downside is over-trusting a "prediction" that is statistically no better than flipping a coin. For actual sex determination, NIPT and the mid-trimester anatomy scan are the evidence-based options most clearly supported by the sources used here. For pregnancy dating and timing questions, our Due Date Calculator and Conception Calculator give date-based estimates in your browser, no data sent anywhere.