Calculate your recommended healthy weight gain range during pregnancy based on your pre-pregnancy BMI. Track weekly progress using official ACOG & IOM guidelines.
Select Unit System
IOM/ACOG Reference Chart — Single Pregnancy
| BMI Category | Pre-Preg BMI | Total Gain (lbs) | 2nd/3rd Trim (lbs/wk) |
|---|---|---|---|
| Underweight | < 18.5 | 28–40 | 1–1.3 |
| Normal Weight | 18.5–24.9 | 25–35 | 0.8–1 |
| Overweight | 25–29.9 | 15–25 | 0.5–0.7 |
| Obese | ≥ 30 | 11–20 | 0.4–0.6 |
Get your pregnancy weight gain recommendation in three simple steps.
Choose Imperial (lbs/ft) or Metric (kg/cm) and enter your height and weight from before you were pregnant. This is used to calculate your pre-pregnancy BMI, which determines your recommended weight gain range.
Choose whether you are expecting a single baby or twins — this significantly affects the recommended range. Optionally enter your current pregnancy week and current weight to see a progress bar and on-track status.
Click Calculate to see your pre-pregnancy BMI, BMI category, total recommended weight gain range, weekly gain rate for the 2nd and 3rd trimesters, first trimester guideline, and a visual progress tracker if tracking details were entered.
Use these results as a starting point for conversations with your OB-GYN or midwife. Your provider may adjust targets based on your unique health history, multiple pregnancies, or other medical factors.
Gaining the right amount of weight during pregnancy is one of the most important factors in ensuring both maternal and fetal health. Too little weight gain can lead to low birth weight and preterm delivery, while excessive weight gain increases the risk of gestational diabetes, preeclampsia, macrosomia (large baby), and cesarean delivery. Our pregnancy weight gain calculator uses evidence-based guidelines from the Institute of Medicine (IOM) and the American College of Obstetricians and Gynecologists (ACOG) to provide personalized recommendations.
The recommended healthy weight gain during pregnancy is based on your pre-pregnancy Body Mass Index (BMI). Women who were underweight before pregnancy (BMI under 18.5) generally need to gain the most — 28 to 40 pounds for a single baby. Normal-weight women (BMI 18.5–24.9) should aim for 25–35 pounds. Overweight women (BMI 25–29.9) are advised to gain 15–25 pounds, and obese women (BMI ≥ 30) should gain 11–20 pounds. For twin pregnancies, these ranges are substantially higher across all categories.
Pregnancy weight gain is not linear — most women gain very little in the first trimester (roughly 1–4 lbs), with the majority of weight gained during the second and third trimesters at a rate of approximately 0.5 to 1 pound per week, depending on BMI category. The weight you gain during pregnancy includes the baby, placenta, amniotic fluid, increased blood volume, uterine growth, breast tissue, and maternal fat stores needed for breastfeeding.
This tool is designed for educational and planning purposes. We strongly encourage all pregnant women to work closely with their obstetric care team to create a weight management plan tailored to their individual needs, lifestyle, and medical history. Use the optional weekly tracking feature to monitor your progress and identify whether you are on track with your personalized goals.
Common questions about pregnancy weight gain and how to use this calculator.