Pregnancy is the one time weight gain is the goal — but how much is healthy depends on where you started. The guidance is a range, tailored to your pre-pregnancy BMI, and it is worth understanding rather than worrying over.
TL;DR — Enter your pre-pregnancy weight, height and current week in the pregnancy weight gain calculator for the recommended range.
Why your starting point matters
The Institute of Medicine bases its recommendations on your pre-pregnancy BMI. Someone who started underweight is advised to gain more; someone who started with a higher BMI, less. For a normal BMI, the typical range is about 11.5–16 kg for a single baby. These bands support the baby’s growth while keeping risks lower for both of you.
How gain spreads across pregnancy
Gain is not even across the months. The first trimester usually adds only a little — often half a kilo to two kilos total. Most healthy weight gain happens steadily through the second and third trimesters, as the baby grows fastest. The calculator shows both the recommended total and what is expected by your current week.
It’s a guide, not a rule
Every pregnancy is different, and your clinician watches your gain alongside many other factors. Gaining a little outside the range is not automatically a problem, and the guidance here is for a single baby. Use the pregnancy weight gain calculator for context, and follow your care team’s advice first.