What are my odds of having twins?
Type the mother’s age at the birth and, if you like, her race and Hispanic origin. The odds of having twins calculator shows the share of US births that were twins for mothers like her, as a percent and as about 1 in N. It describes all births, not a personal prediction.
- Chance of twins (by age)
- 3.62%
For a mother aged 32, about 3.62% of births are twins, about 1 in 28.
- About 1 in
- 28
- Age group
- 30 to 34
- US average
- 3.26%
Chance of twins (by age): 3.62%. For a mother aged 32, about 3.62% of births are twins, about 1 in 28.
This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use
How to calculate
Shows the chance that a birth is twins for a mother of your age, and of your race and Hispanic origin, from the US twin birth rates for 2018 (NCHS), as a percent and as 1 in N.
Example with the default inputs (Mother’s age at birth 32, Race and Hispanic origin Any): For a mother aged 32, about 3.62% of births are twins, about 1 in 28.
Method: Chance = twin births per 1,000 births for the age group (or race and Hispanic origin group) ÷ 10, in percent; 1 in N = 1,000 ÷ rate.
- US births in 2018; the rates include twins conceived with fertility treatment.
- The age rate and the group rate are separate published rates; they are not combined.
- A rate for all births is not a personal prediction for one pregnancy.
Worked examples
Each example is checked against the calculator on every build.
- Mother’s age at birth 32, Race and Hispanic origin Any gives Chance of twins (by age) 3.62%, About 1 in 28, Age group 30 to 34, US average 3.26%.Source: Martin JA, Osterman MJK, NCHS Data Brief No. 351, Is Twin Childbearing on the Decline? United States, 2014–2018 (twin birth rates per 1,000 births, 2018), https://www.cdc.gov/nchs/products/databriefs/db351.htm (retrieved 2026-10-05)
- Mother’s age at birth 41, Race and Hispanic origin Black gives Chance of twins (by age) 5.11%, About 1 in 20, Age group 40 and over, Chance of twins (by race and Hispanic origin) 4.05%, About 1 in (by group) 25.Source: Martin JA, Osterman MJK, NCHS Data Brief No. 351, Is Twin Childbearing on the Decline? United States, 2014–2018 (twin birth rates per 1,000 births, 2018), https://www.cdc.gov/nchs/products/databriefs/db351.htm (retrieved 2026-10-05)
- Mother’s age at birth 19, Race and Hispanic origin Hispanic gives Chance of twins (by age) 1.71%, About 1 in 58, Age group under 20, Chance of twins (by race and Hispanic origin) 2.44%, About 1 in (by group) 41.Source: Martin JA, Osterman MJK, NCHS Data Brief No. 351, Is Twin Childbearing on the Decline? United States, 2014–2018 (twin birth rates per 1,000 births, 2018), https://www.cdc.gov/nchs/products/databriefs/db351.htm (retrieved 2026-10-05)
How it works
Twin birth rates per 1,000 births in the United States in 2018 (NCHS Data Brief 351):
| Mother’s age | Twins per 1,000 births |
|---|---|
| Under 20 | 17.1 |
| 20 to 24 | 23.2 |
| 25 to 29 | 30.4 |
| 30 to 34 | 36.2 |
| 35 to 39 | 42.8 |
| 40 and over | 51.1 |
| Race and Hispanic origin | Twins per 1,000 births |
|---|---|
| Non-Hispanic white | 34.3 |
| Non-Hispanic Black | 40.5 |
| Hispanic | 24.4 |
| All US births | 32.6 |
- Chance of twins (by age) = the age group’s rate ÷ 10, in percent (36.2 per 1,000 is 3.62%).
- About 1 in = 1,000 ÷ the rate, rounded half up to a whole number.
- With a race and Hispanic origin group chosen, the same two numbers for that group’s rate. With “Any”, only the age rate shows.
- US average = 32.6 ÷ 10 = 3.26%.
Rules. Age is a whole number from 12 to 55. The age group is chosen by age: under 20, 20 to 24, and so on.
Output format. Percents show 2 decimals, rounded half up from the exact value.
Assumptions
- Births, not pregnancies: a twin pregnancy that ends early is not counted.
- The rates include twins after fertility treatment.
Worked examples by hand
Mother aged 32, any group. Age group 30 to 34: 36.2 per 1,000 = 3.62%. 1,000 ÷ 36.2 = 27.62, so about 1 in 28. US average 3.26%.
Mother aged 41, non-Hispanic Black. Age group 40 and over: 51.1 per 1,000 = 5.11%; 1,000 ÷ 51.1 = 19.57, about 1 in 20. Group: 40.5 per 1,000 = 4.05%; 1,000 ÷ 40.5 = 24.69, about 1 in 25.
Mother aged 19, Hispanic. Under 20: 17.1 per 1,000 = 1.71%; 1,000 ÷ 17.1 = 58.48, about 1 in 58. Group: 24.4 per 1,000 = 2.44%; 1,000 ÷ 24.4 = 40.98, about 1 in 41.
Other questions people ask
What are the odds of having twins?
In the United States in 2018, 32.6 of every 1,000 births were twins, about 3.3%, or 1 in 31. The chance is higher for older mothers and differs by race and Hispanic origin.
Does the mother’s age change the odds of twins?
Yes. In 2018 the twin rate rose from 17.1 per 1,000 births for mothers under 20 to 51.1 per 1,000 for mothers 40 and over.
Do twins run in families?
The published US rates are not split by family history, so this page cannot add it. Ask your doctor how your own history changes your chances.
Do the rates include fertility treatment?
Yes. They count all US births in 2018, including births after fertility treatment, so they are not rates for natural conception only.
Why do the age and race results differ?
They are two separate published rates: one for all mothers of an age group, and one for all mothers of a race and Hispanic origin group. The page shows both and does not combine them, because the source gives no combined table.
Is the twin rate going down?
The US twin birth rate fell from 33.9 per 1,000 births in 2014 to 32.6 in 2018 (NCHS Data Brief 351).