Pregnancy Weight Gain Calculator
Calculate recommended pregnancy weight gain based on your pre-pregnancy BMI. Track your weight gain throughout pregnancy using IOM guidelines.
Formula:Target Gain = IOM Range based on Pre-pregnancy BMI
Weight Gain Status
Current Gain
10.0 lbs
Within recommended range
Pre-pregnancy BMI23.3 (Normal Weight)
Recommended at Week9.0 lbs
Total Recommended25-35 lbs
Pregnancy Details
weeks
142
Measurements
Weight Gain Progress
Week 20 of 4010.0 lbs gained
Your Gain
10.0 lbs
Expected
9.0 lbs
Total Goal
25-35
Weight Gain Projection
Shaded area shows recommended weight range throughout pregnancy
IOM Weight Gain Guidelines
| Pre-pregnancy BMI | Total Gain (lbs) | Weekly Rate (2nd/3rd) |
|---|---|---|
| Underweight (<18.5) | 28-40 lbs | 1.0-1.3 lbs |
| Normal (18.5-24.9) | 25-35 lbs | 0.8-1.0 lbs |
| Overweight (25-29.9) | 15-25 lbs | 0.5-0.7 lbs |
| Obese (30+) | 11-20 lbs | 0.4-0.6 lbs |
Where Does Pregnancy Weight Go?
Baby
7-8 lbs
Placenta
1-2 lbs
Amniotic Fluid
2 lbs
Uterus
2 lbs
Breast Tissue
2 lbs
Blood Volume
4 lbs
Body Fluids
4 lbs
Fat Stores
5-9 lbs
Weight Gain Scenarios
Explore how changes affect your results
Weight Gain vs Normal Weight Range
Compared to the general population
Your Weight Gain
10.0 lbs
Percentile
5th
Below average - looking good!
Distribution
You
Low
12.7
Below
20.3
Target
30.3
Above
38.8
High
45.9
Your Ranking
Top 5%
95% are higher
Pregnancy Weight Tips
Based on your results
0/4 completed
⚕️ MedicalOptional
Your Status
You've gained 10.0 lbs at week 20, which is within the recommended range. Keep up the healthy habits!
🥗 NutritionRecommended
Nutrition Guidance
Second trimester: Add about 340 extra calories/day. Increase protein and calcium intake.
⚕️ MedicalRecommended
Your BMI Category
With a pre-pregnancy BMI of 23.3 (Normal Weight), your total recommended gain is 25-35 lbs.
Frequently Asked Questions
Weight gain depends on your pre-pregnancy BMI. Underweight (BMI <18.5): 28-40 lbs. Normal weight (BMI 18.5-24.9): 25-35 lbs. Overweight (BMI 25-29.9): 15-25 lbs. Obese (BMI 30+): 11-20 lbs. Twin pregnancies require more weight gain.
Most women gain little weight in the first trimester (0-4 lbs). Weight gain picks up in the second trimester with about 1 lb per week. Some women may lose weight early due to morning sickness, which is usually not concerning.
Excess weight gain increases risk of gestational diabetes, high blood pressure, larger baby (making delivery harder), and difficulty losing weight postpartum. It doesn't harm the baby directly but can complicate pregnancy and delivery.
Insufficient weight gain may increase risk of preterm birth and low birth weight baby. Talk to your healthcare provider about calorie-dense, nutritious foods. Some women need help managing nausea to eat adequately.
Baby: 7-8 lbs. Placenta: 1.5 lbs. Amniotic fluid: 2 lbs. Uterus growth: 2 lbs. Breast tissue: 2 lbs. Blood volume: 4 lbs. Body fluids: 4 lbs. Fat stores: 5-9 lbs (for breastfeeding and energy).
How this works
Formulas are implementations of published clinical or public-health equations. Calculations run in your browser — no inputs are transmitted to our servers and no account is required. The result is informational; it does not diagnose, treat, or replace advice from a clinician.
What this tool can’t do
When to consult a professional
Talk to a licensed healthcare provider before using the output of this tool to make a medical decision, especially if you have an underlying condition, are pregnant, or are on medication that affects metabolism or fluid balance.
Sources
- [1]Centers for Disease Control and Prevention (CDC)Official sourcecdc.govAccessed Apr 21, 2026
- [2]National Institutes of Health (NIH)Official sourcenih.govAccessed Apr 21, 2026
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).
Weight Gain Status
Current Gain
10.0 lbs
Within recommended range
Pre-pregnancy BMI23.3 (Normal Weight)
Recommended at Week9.0 lbs
Total Recommended25-35 lbs