Pregnancy Weight Gain Calculator

Based on WHO & Chinese NHC dual standards, supports single & multiple pregnancies, real-time gain curve, AI diet & exercise advice, alerts, chart export—covering pre-conception to late pregnancy for scientific weight management.

Assess Now Features

Pregnancy Weight Gain Assessment

Enter pre-pregnancy data to get a personalized gain plan and real-time tracking

kg
Weight closest to conception
cm
Barefoot standing height
Affects metabolism (optional)
Different standards for multiples
weeks
For real-time comparison
kg
Today fasting weight
kg
Auto-calculated range

How the Calculator Works

Calculation Logic

Based on guidelines from the Institute of Medicine (IOM) and the U.S. Centers for Disease Control and Prevention (CDC), the tool estimates healthy weekly weight gain during pregnancy.

It first classifies your pre-pregnancy BMI, then applies the IOM recommended total gain ranges:

  • Underweight (BMI < 18.5): 28–40 lb (12.7–18.1 kg)
  • Normal (18.5–24.9): 25–35 lb (11.3–15.9 kg)
  • Overweight (25–29.9): 15–25 lb (6.8–11.3 kg)
  • Obese (≥ 30): 11–20 lb (5.0–9.1 kg)
  • Twin pregnancies: higher ranges apply

The model assumes slow gain in the 1st trimester, then steady weekly gains in the 2nd & 3rd, forming a realistic curve. Weekly ranges ensure total gain meets IOM targets by week 40.

Reading the Chart

The pink shaded area between the blue and red lines shows the recommended range; the orange dot is your current weight.

💡 Understanding Results
🟢
Within Range

Your weight is on track. Keep balanced meals, hydration, and moderate activity. Small weekly fluctuations are normal—focus on the overall trend.

🔴
Below Range

Can happen in the 1st trimester due to nausea. Discuss with your provider to ensure fetal growth and get tips for healthy gain.

🔴
Above Range

Slight overshoot is common, but steady rapid gain may raise risks of GDM or hypertension. Review diet & lifestyle with your provider—small adjustments can bring you back to target.

Note: This calculator is for screening only, not a diagnosis. Always discuss results with your healthcare provider.
Evidence

The Institute of Medicine (IOM) provides the most widely accepted framework for gestational weight gain. These recommendations balance maternal nutrition, optimal fetal development, and long-term health.

Guidelines are derived from studies of >120 000 pregnancies, analyzing links between maternal gain and outcomes such as preterm birth, fetal growth, and postpartum recovery.

Tips
  • • Weigh 1–2 times per week, same time (morning, fasting)
  • • Focus on trend, not daily fluctuation
  • • Balanced diet, moderate exercise
  • • Consult your provider with any concerns

Authority Standards Comparison

Chinese NHC vs IOM 2009 Guidelines

Pre-pregnancy BMI Single Gain (kg) Twin Gain (kg) 2nd/3rd Tri Weekly Gain (kg/w) China IOM
Underweight
<18.5
12.5–18.0 n/a 0.44–0.58
Normal
18.5–23.9
11.5–16.0 17–25 0.35–0.50
Overweight
24.0–27.9
7.0–11.5 14–23 0.23–0.33
Obese
≥28.0
5.0–9.0 11–19 0.17–0.27
Tip: No Chinese national standard for multiples; IOM ranges recommended. For GDM, GH or other high-risk conditions, individualized management under your provider is required.

IOM 2009 Gestational Weight Gain Guidelines

Single Pregnancy
Pre-pregnancy BMI Category Recommended Total Gain 1st Trimester 2nd & 3rd Trimester (per week)
< 18.5 Underweight 28–40 lb
(12.5–18 kg)
2–5 lb
(1–2 kg)
1.0 lb/wk
(0.45 kg/wk)
18.5–24.9 Normal 25–35 lb
(11.5–16 kg)
1–4.5 lb
(0.5–2 kg)
1.0 lb/wk
(0.45 kg/wk)
25–29.9 Overweight 15–25 lb
(7–11.5 kg)
0.5–2 lb
(0.2–1 kg)
0.6 lb/wk
(0.27 kg/wk)
≥ 30 Obese 11–20 lb
(5–9 kg)
0.5–1.5 lb
(0.2–0.7 kg)
0.5 lb/wk
(0.22 kg/wk)
Twin Pregnancy
Pre-pregnancy BMI Category Recommended Total Gain
< 18.5 Underweight 50–62 lb
(22.5–28 kg)
18.5–24.9 Normal 37–54 lb
(17–25 kg)
25–29.9 Overweight 31–50 lb
(14–23 kg)
≥ 30 Obese 25–42 lb
(11–19 kg)
Data source: Institute of Medicine (IOM) 2009 guidelines, based on analysis of >120 000 pregnancy outcomes.

Friendly Reminders

Important: The following standards are for reference only; always consult your provider for individual advice.
1
Pre-pregnancy Standard Weight

Standard weight (kg) = (height in m)² × 21 (ideal 22). Example: 160 cm → 1.6² × 21 = 53.76 kg.

2
Obesity Degree

Degree = (actual − standard) / standard × 100 %. >20 % warrants attention.

3
Obesity BMI Categories

BMI = kg / m². <20 underweight, 20–24 normal, 24–26.4 mildly overweight, >26.4 obese.

4
Ideal Delivery Weight

Ideal = (pre-BMI × 0.88 + 6.65) × (height m)². Usually 7–10 kg above pre-weight.

5
Short Stature Alert

<150 cm mothers need extra care—narrow pelvis↑ delivery difficulty risk; avoid excessive fetal/macronutrient gain.

6
Post-Morning-Sickness Management

After nausea resolves, prevent rebound overeating. Limit weekly gain to ≤0.5 kg; if >0.5 kg or edema appears, consult promptly.

Why Choose PreMami Weight Gain Calculator?

Dual Standards

Follows both Chinese NHC & IOM 2009 guidelines, auto-selects the best range for Asian moms.

Real-time Curve

Visual line/bar charts, weekly & cumulative gains at a glance, export high-res images.

AI Advice

Auto-generates diet & exercise plans and alerts based on BMI, week and gain speed.

Multiple Mode

Switch among single/twin/triplet in one click; IOM ranges auto-applied for accuracy.

One-click Export

PDF report, Excel table, HD curve—hand them to your doctor at visits for efficient communication.

Social Share

Generate beautiful long images for WeChat, Weibo, Xiaohongshu—show your self-discipline and earn likes.

Step-by-Step User Guide

Learn to record, interpret and intervene in 3 min—stay away from GDM & hypertension

Steps
  1. Enter pre-pregnancy weight & height—BMI is auto-calculated and classified (underweight/normal/overweight/obese).
  2. Select fetus count—single uses Chinese standard; twins/triplets auto-load IOM ranges.
  3. Fill current week & weight—supports one-time assessment or continuous tracking.
  4. View results—real-time curve, health grade, AI diet & exercise advice.
  5. Record & export—add weight weekly/daily, export PDF/Excel, bring report to visits.
Gain too fast/slow?
  • Too fast: cut refined carbs & sugary drinks; 30 min brisk walk + prenatal yoga daily; monitor BP & glucose.
  • Too slow: add quality protein, nuts, full-fat milk; small frequent meals; rule out hyperemesis or hyperthyroidism.
Alert Thresholds
>0.7 kg weekly for 2 weeks
<0.1 kg weekly for 2 weeks
Total gain >90 % of upper limit
Weight drop ≥1 kg/week
Best Weighing Practice
  • ✅ Same time daily (morning, fasting)
  • ✅ Same scale, same spot
  • ✅ No shoes, light clothes
  • ✅ Average weekly values to reduce noise