The pregnancy weight gain calculator can help you discover how much you’ve put on during singular or twins pregnancy. Refer to under the form area for more information on pregnancy weight and on the general guidelines on this subject.

Weight before pregnancy:*
Is it a multiple pregnancy?*

How does the pregnancy weight gain calculator work?

The useful tool can help both future moms and their families discover the health regulations for pregnancy weight according to their weight category. The calculation can be adapted to the case of a single carrying pregnancy or one with twins.

You are therefore asked to input your height and weight before pregnancy in order to determine your BMI, which is the body mass index value. This indicator will then be used to see in which weight category you stand as to see where you belong in the health guidelines for normal pregnancy weight gain.

You will then receive a comprising answer telling you your weight category, how much pregnancy weight you can gain in a healthy and responsible way and also how this amount could be distributed during your time being pregnant.

A bit on the importance of BMI

The body mass index (BMI) is an indicator of your weight in relation to your height and can reflect whether you are having a healthy weight or not. The amount that should be put during pregnancy depends on what the BMI was before you were pregnant.

BMI values and the weight categories:

BMI range Category of weight
< 18.5 Underweight
18.5 and 25 Normal weight
25 and 29 Overweight
> 30 Obese

Why is the before pregnancy weight so important?

The BMI calculation in the pregnancy weight gain calculator will indicate where this weight stands in terms of underweight, normal weight, overweight and obese. While there is no issue regarding those with a normal weight when it comes to carrying a baby, the extremes should be discussed.

The women with an underweight classification before pregnancy should take real care on putting some weight on besides the normal one in pregnancy because they have a higher risk of miscarriage or fetal complications.

The women who are overweight or obese should watch out their weight as not to gain more than the one normally expected in pregnancy as they pose a higher risk of miscarriage, early labor, premature birth and other fetal complications.

Pregnancy weight gain guidelines

These guidelines are designed to accommodate the general weight before pregnancy but also the existence of a multiple pregnancy with twins.

The first chart indicates the values for a pregnancy with one baby for each of the four weight stages both in lbs and kg while the second chart shows the same guidelines but this time for a pregnancy with twins:

Pregnancy with one baby:

Weight situation BMI Lbs to put on Kg to put on
Underweight 28 – 40 13 – 18
Normal weight 25 – 35 11 – 16
Overweight 15 – 25 7 – 11
Obese 11 – 20 5 – 9

Pregnancy with twins:

Weight situation BMI Lbs to put on Kg to put on
Underweight 28 – 40 13 – 18
Normal weight 37 – 54 17 – 25
Overweight 31 – 50 14 – 23
Obese 25 – 42 11 – 19

■ You might also find informative the conception calendar that keeps track of your menstrual cycle and of the dates such as the ovulation date for the following 12 months together with the pregnancy due date, or it can find the conception date.

■ Beside this calculator you could be interested in the pregnancy week calculator that gives you a detailed description of your pregnancy week.

Example of a calculation

In the case of a twin pregnancy occurring in a woman with a height of 5 feet 4 inches and a weight before pregnancy of 120 lbs, the results of the tool are:

■ BMI value before pregnancy: 20.6. This value belongs to the Normal weight.

■ Having a normal weight means that you should simply have a healthy lifestyle and simply stay in the guidelines of normal pregnancy gain.

■ In case of a pregnancy with more babies the recommended pregnancy weight gain would be between 37 and 54 lbs for the whole pregnancy.


1) Wylie L. (2005) Essential anatomy and physiology in maternity care (2nd ed.) Edinburgh: Churchill Livingstone.

2) Bateson P. (2001) Fetal experience and good adult design. International Journal of Epidemiology 30 (5): 928–934

3) Institute of Medicine. (2009) Weight Gain During Pregnancy: Reexamining the Guidelines.

10 Dec, 2014