Try the Chinese gender calendar, the Mayan parity method, and a parent-traits predictor side by side. Just for fun — these are traditions, not medical predictions.
Written by the babybumpkit editorial team.
Heads-up: none of the methods on this page predict biological sex with better-than-chance accuracy. They're traditions and old wives' tales. The only reliable methods are medical — see the section below for when a doctor can actually tell you.
How the Chinese gender calendar works
The Chinese gender calendar is a centuries-old chart that cross-references the mother's lunar age at conception with the lunar month she conceived in, returning “boy” or “girl” from a fixed lookup table. Tradition holds that a copy was buried in a Beijing tomb roughly 700 years ago, though the actual provenance is debated by historians.
In practice, the calendar performs at chance level — about 50% accurate, the same as flipping a coin. The version on this page uses the standard 28×12 table that appears across virtually every English-language Chinese calendar tool, with the simplifying assumption that lunar age is roughly the mother's age plus one. It's a tradition many parents enjoy trying, not a prediction to plan around. If you want to read the full chart yourself or see your result highlighted on it, our standalone Chinese gender calendar page publishes the entire 28×12 table.
The Mayan method explained
The Mayan method is the simplest of the three: take the mother's age at conception and the year of conception. If both numbers are even, or both are odd, the prediction is girl. If one is even and the other is odd, the prediction is boy.
Like the Chinese calendar, this is folklore — by definition, parity-based prediction can't do better than chance because biological sex isn't correlated with calendar parity. People enjoy the method partly because it's easy to remember and partly because the result often disagrees with the Chinese calendar, giving you two predictions to talk about.
Predicting from parent traits
The third method asks five quick questions about pregnancy symptoms — cravings, morning-sickness severity, how you're carrying, mood intensity, and skin changes — and aggregates them into a soft probabilistic guess. Each question is rooted in old wives' tales: sweet cravings traditionally suggest a girl, salty cravings suggest a boy, severe morning sickness leans girl, and so on.
A few of these signals (notably morning-sickness severity) have shown a faint statistical association with biological sex in real-world studies, but the overlap is huge and they're not reliable for any individual pregnancy. We cap the “confidence” result at 90% no matter how lopsided your answers are, because the underlying signal genuinely isn't that strong.
How accurate are gender prediction methods?
The honest answer: traditional methods perform at roughly chance level. The only reliable ways to determine biological sex during pregnancy are medical:
NIPT (non-invasive prenatal testing) — a blood draw from the mother that detects fetal DNA. Reliable from about 9–10 weeks of gestation onward; over 99% accurate for sex when enough fetal DNA is present.
Mid-pregnancy anatomy ultrasound — typically between 18 and 22 weeks. Very accurate when the baby cooperates and a clear view is available.
Amniocentesis or chorionic villus sampling (CVS) — definitive, but only offered when there's a medical reason because both carry a small miscarriage risk.
If knowing your baby's sex matters, talk with your healthcare provider about which medical option is appropriate for your pregnancy and timeline.
When can I find out my baby's gender medically?
The earliest reliable answer comes from NIPT at 9–10 weeks. Most practices run NIPT primarily as a chromosomal screening; sex determination is offered as part of the same report if you opt in.
If you're not having NIPT, the anatomy scan between 18 and 22 weeks is the most common moment parents find out. Sonographers can often see external genitalia clearly by then, though the baby's position can sometimes prevent a confident call. If that happens, a follow-up scan usually clears it up.
Frequently asked questions
Studies that have actually tested the Chinese gender calendar against real birth outcomes find its accuracy is around 50% — the same as a coin toss. It feels accurate to a lot of people because the result is binary, so you have a one-in-two chance of being “right” no matter what. Treat it as folklore and a fun tradition, not a medical prediction.
Not reliably. The methods on this page can be tried before conception by using a planned conception date, but their predictions don't influence the actual outcome. The only methods that influence biological sex selection are clinical (such as PGT-A during IVF), which is regulated and only available for specific medical reasons in most countries.
Non-invasive prenatal testing (NIPT) can determine biological sex from a blood draw as early as 9–10 weeks. The mid-pregnancy anatomy ultrasound at 18–22 weeks usually shows external genitalia clearly. Amniocentesis (typically 15–20 weeks) is the most definitive but is only offered when there's a medical reason because it carries a small miscarriage risk.
There is no proven at-home method that can predict biological sex with better than chance accuracy. Drugstore “gender prediction kits” based on urine, baking soda, or ring tests have all failed peer-reviewed testing. The only at-home option that does work is an at-home blood-collection kit that's then sent to a lab for NIPT — but that's not really at-home, it's a sample-collection step.
NIPT (also called cell-free DNA screening) looks for fetal DNA in the mother's bloodstream and can typically determine biological sex from about 9–10 weeks of gestation onward. Earlier than that, there often isn't enough fetal DNA in the sample to give a confident result. NIPT also screens for chromosomal conditions, which is its main medical purpose — sex determination is a useful side benefit.
There's a weak association in some research: people carrying girls report slightly more severe morning sickness on average, possibly linked to higher hCG levels. But the overlap between “severe sickness with a boy” and “mild sickness with a girl” is huge. It's nowhere near accurate enough to predict an individual pregnancy.
No — bump shape is determined by your body type, abdominal muscle tone, baby's position, and how many pregnancies you've had before. Whether you carry “high” or “low” has no relationship to biological sex. It's one of the oldest pregnancy myths and one of the easiest to disprove with a quick search of birth statistics.
Biological sex refers to chromosomes (XX, XY, or rarer combinations) and physical characteristics. Gender is a social and personal identity that may or may not align with assigned sex at birth. Prenatal tests detect biological sex; gender identity emerges later as the child grows up. Pages like this one use “gender” colloquially because that's how the search terms are written.
Yes — fraternal (dizygotic) twins come from two separately fertilized eggs and can be different sexes about 50% of the time. Identical (monozygotic) twins come from a single fertilized egg that splits, so they share the same chromosomes and are almost always the same sex. The only extremely rare exception involves chromosomal abnormalities.
Most have no scientific basis at all — heart rate, ring tests, baking-soda tests, and the Chinese calendar all perform at chance level when properly studied. A few myths (like morning-sickness severity) have a weak statistical signal but aren't reliable for predicting any individual pregnancy. They're fun to try; they shouldn't be the basis of any decision.