Chances of Having Twins Calculator

Created by Dominika Śmiałek, MD, PhD candidate
Reviewed by Dominik Czernia, PhD, Jack Bowater and Aleksandra Zając, MD
Based on research by
Kulkarni AD, Jamieson DJ, Jones HW, Kissin DM, Gallo MF, Macaluso M, Adashi EY. Fertility Treatments and Multiple Births in the United States The New England Journal of Medicine (Dec 2013)See 1 more source
American Society of Reproductive Medicine Multiple Pregnancy and Birth: Twins, Triplets, and High Order Multiples (2012)
Last updated: Dec 22, 2022

Double the trouble, double the fun, double the love! (Or maybe triple?) With our chances of having twins calculator, you can calculate what are the chances of having twins, triplets, or any other multiple pregnancy.

Multiple pregnancies are now a hot topic, as ARTs (assisted reproductive technology), such as in vitro fertilization, are making women more fertile and susceptible to twins. It is even possible to plan and estimate the due date prior to conception with IVF, with an IVF due date calculator.

As more and more women give birth to more than just one baby, you may ask, "Why is that a thing?", "What are my chances of having twins?", and "How to have twins?" Answers to these questions, and more, can be found in the article below.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. If any health condition bothers you, consult a physician.

Types of multiple pregnancies – how do they happen?

Multiple pregnancies aren't a common thing. One could say that this is natural – pregnancy is burdensome on the mother's body, as she has to feed the fetus and give it space to grow and develop until he or she is ready to be born. In the cases of multiple pregnancies, things become more complicated. To keep both the babies and the mother safe, birth often has to be induced before the due date to keep everyone safe. This day may be estimated with a due date calculator.

What are the types of multiple pregnancies?

  • Monozygotic twins, where a single egg cell is fertilized by a single sperm cell. Later, it splits into two instead of growing into just one embryo. The children have the exact same genetic material and are always of the same sex. They also look identical.
  • Dizygotic twins, where two egg cells are released during one ovulation and then fertilized by two sperm cells. The ovulation day may be estimated with ovulation calculator. Our calculator is mostly concerned with this type of pregnancy, as it is more common and more influenced by external factors. The children look different, as their DNA is also different. They may be of two different sexes – akin to regular brothers and sisters.
  • Triplets, quadruplets, etc. The more babies that were conceived, the more eggs were fertilized by sperm cells. These types are increasingly less likely to happen naturally – 1 in 10,000 for triplets and 1 in 70,000 for quadruplets.

What are the chances of having twins, triplets, or quadruplets naturally?
For monozygotic twins, the chances are 0.3%. In the case of dizygotic twins, the odds go up to 0.4%. For triplets, the natural probability is 0.01%, and for quadruplets, it's a minuscule 0.00014286%.

Factors that influence your odds of having twins

There are several factors that either increase or decrease your chances of having dizygotic twins. Among them, a surprising one is ethnicity, as Hispanic couples are the least prone to having twins. Caucasian parents are more likely, but Afro-Americans have the highest chances of conceiving a multiple pregnancy.

The most significant factor that affected the number of twin pregnancies recently is ART treatment, which causes them to increase dramatically. This is not limited to only in-vitro fertilization but also hormonal therapy.

How to have twins with natural methods? Well, unfortunately, there's not a lot you can do about it as it is mainly genetic. Most people know that having twins in their family gives them some hope they may conceive twins. Twins on the mother's side are more influential than on the father's.

What are my chances of having twins if I've already had one pair? The odds of having a new pair are high – up to 1 in every 17 pregnancies!

What became very clear after WW2 and during every period of famine is that the taller and stronger the mother is, the higher her odds of having twins. What might be the reason? Scientists suggest that larger moms have more nutrients stored, and therefore, the babies' development is not disturbed, even if they're two or more.

Women suffering from obesity (BMI over 30) are more likely to get pregnant with twins, which is probably due to hormonal disintegration. BMI calculator for women may be of use to estimate this factor. Excessive adipose tissue produces estrogens. This hormone causes the maturation of eggs and ovulation. If there's too much of it, more than one egg (which is the typical number) matures and moves toward the fallopian tubes. This allows the sperm cells to fertilize more than just one egg.

How to calculate my chances of having twins? – Chances of having twins calculator

In the first box, you can choose what type of multiple pregnancies you want to calculate the odds for. The following result is the chances of a natural conception.

The rest of the calculator is designed for dizygotic twins. First, select your ethnicity if it's present, and we will show you what are the overall odds for a couple of that ethnicity.

The next six questions focus mainly on known factors that increase the couple's chances of conceiving twins. Choose your factors; you can also play with the tool and get to know which factors increase the odds significantly. Note, however, that you cannot add the numbers together to get your overall chance. Of course, having more than one increasing factor will increase your overall odds a bit more.

OK, so now you know how to calculate your chances of having twins. But how does one get pregnant with them?

How can I increase my chances of having twins?

If your dream is to have twins or triplets, there's unfortunately not much you can do. Most of the factors affecting the probability are genetic or connected with your body weight. And risking obesity for the sake of increased chances for twins is not the best option.

You can always talk with your physician about ART (assisted reproductive technology), which includes pharmacotherapy or in-vitro fertilization, which puts your hormonal regulations at risk again.


What are my chances of having non-identical twins?

1 in 85 is the number for the general population. Keep in mind that your chances strongly depend on various factors like your genetics, ethnicity, age, weight, etc.

What factors affect the chances of having twins?

Your chances of getting pregnant with twins depend on your:

  • Genetics (history of twins in the family);
  • Race (Afro-Americans are more likely to have twins);
  • Age (the older the mother, the higher the chances of twins);
  • Height and weight (overweight and tall women have twins more often); and
  • Fertility treatments (they increase your chances).

Where are the most twins born?

Most twins (more than 18 per 1,000 births) are born in the African countries of Benin, Nigeria, and Togo.

Scientists suspect that this high twinning rate is due to the diet, which is rich in foods that stimulate ovulation.

Dominika Śmiałek, MD, PhD candidate
Overall chances of having a multiple pregnancy
Type of pregnancy
Dizygotic twins 👧👦
Naturally, dizygotic twins occur only in 1:85 pregnancies.
What increases the chances of having dizygotic twins?
Your ethnicity
Did you get pregnant with the help of ART? 💉
Do you have nonidentical twins in your family?
Have you already have twins? 👧👦
Does the mom-to-be have a twin brother/sister?
What's the mom-to-be's height?
What's the mom-to-be's weight? ⚖️
✔️ White couples have a medium chance of having twins when compared with other ethnicities - almost 3.5 in 100 pregnancies.
You are not at an increased chance of conceiving twins.
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