Chinese Gender Chart Accuracy: What the Evidence Actually Shows

The Chinese gender chart predicts baby sex at roughly 50 percent, which is chance. The two largest published studies, a 2010 population analysis of 2.8 million Swedish births and a 2014 retrospective in New Zealand, both 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, and the origin is usually attributed vaguely to the Qing Dynasty without a verifiable primary source. You can see the actual chart and try it on our Chinese Gender Chart tool.

What the data actually says

Two peer-reviewed studies have directly tested the chart against real outcomes.

Villamor et al. (2010) cross-referenced the chart against 2,840,029 births recorded in the Swedish Medical Birth Register. The chart predicted the correct sex in 50.2 percent of cases, statistically indistinguishable from random. With two possible outcomes, you cannot fall below 50 percent on average, so this is the floor, not a mild success.

Katz et al. (2014) ran the same test against 691 spontaneous conceptions in a New Zealand cohort and reported 50.0 percent accuracy, again chance-level.

There is no third peer-reviewed study 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: approximately 51 percent of live births are male, so a chart that guessed "boy" every time would be right 51 percent of the time, essentially matching its 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 reports sex with over 99 percent accuracy in most published cohorts. It is typically ordered as part of aneuploidy screening.

First-trimester ultrasound between 11 and 14 weeks can suggest sex based on the genital tubercle angle, with reported accuracy ranging from 70 to 90 percent depending on fetal position and operator experience.

Mid-trimester anatomy scan at 18 to 22 weeks achieves above 95 percent sex accuracy under standard conditions, and is offered routinely in most healthcare systems.

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 population study of 2.8 million births and a 2014 New Zealand study both found accuracy at 50 percent, the same as a coin flip.

What percentage of predictions are correct?

About 50 percent on average. Because there are only two outcomes, you cannot score below 50 percent over a large sample. The chart has nothing distinguishing it from random guessing.

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

An early ultrasound can suggest sex at 70 to 90 percent accuracy depending on position. A 20-week anatomy scan is above 95 percent. Both are far more accurate than the chart.

Can NIPT tell sex earlier than an ultrasound?

Yes. NIPT uses a maternal blood sample and is available from 10 weeks. Sex accuracy is over 99 percent in published cohorts.

Where does the chart come from?

Origin is attributed to the Qing Dynasty, but no verified primary source exists. 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, first-trimester ultrasound, and the 20-week anatomy scan are all meaningfully accurate. For pregnancy dating and timing questions, our Due Date Calculator and Conception Calculator give date-based estimates in your browser, no data sent anywhere.