This pregnancy weight calculator can estimate how much weight you can put on during the 40 weeks of you carrying the baby according to your own health. Read below the tool more on pregnancy weight and other useful information for future moms.


Weight before pregnancy:*
What kind of pregnancy is?*
Pregnancy week*

How does the pregnancy weight calculator work?

This health tool helps all future mommies discover the schedule of normal pregnancy weight gain for the entire pregnancy according to their weight condition.

The health condition is calculated with the help of the BMI formula taking into account the weight and height before pregnancy. The body mass index will then be used to see in which weight category the subject stands as to see where they belong in the health guidelines for normal pregnancy weight gain.

Once you choose the type of pregnancy you’re having (either one baby or twins) and the week of pregnancy you are in, you can push the Calculate button to receive the results.

You are going to be calculated the BMI value, you are going to be given some guideline on how much you are allowed to healthy put on but you are also going to get a description of the weight gain in weeks for your pregnancy.

Don’t forget that you are going to receive the results in the same measurement unit that you input the data so decide from the beginning if you are more comfortable using kg or lbs. You can adjust your input data or change it completely at all times and then press Calculate or Reset.

The body mass index (BMI) uses the weight and height of a person in order to determine a weight category that then reflects the general health state. The amount of weight that should be put during pregnancy depends on what the value was before getting pregnant.

BMI values and the weight categories are as follows:

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

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

How is the pregnancy weight disposed during pregnancy?

During the first trimester of pregnancy there is not such a big amount of weight to be put on, varying at about 4 lbs (2 kg) for the entire 3 first months.

During each week of the second and third trimester of pregnancy the future mom will add about 1 lb (500g). This value can vary however according to the health condition of the mother and the fetal development as pregnant women that have a bigger weight tend to put on less than 1 lb per week.

Check the results in this pregnancy weight calculator to see how your pregnancy is standing for each of the 40 weeks.

You might be interested to discover 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.

Weight gain calculation

Let’s take for example the case of a single pregnancy expectant mother in week 24 with a height of 5 feet and 2 inches and a before weight of 126 lbs. The results given are:

BMI value before pregnancy: 23.0. 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 one baby the recommended pregnancy weight gain would be between 25 and 35 lbs for the whole pregnancy.

Given the Week 24 your weight should be between 137.600 and 143.200 lbs.

*Plus a table with the whole pregnancy time weight gain schedule.


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

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

13 Dec, 2014