Track week-by-week weight gain against IOM 2009 guidelines. Pre-pregnancy BMI decides target: 25–35 lb normal, 15–25 overweight, 11–20 obese.
Direct answers for the most-searched pregnancy BMI queries, using the standard pre-pregnancy BMI formula (BMI = 703 × lb / in²) and IOM 2009 category cutoffs:
Direct answers for the most-searched pregnancy weight gain queries, using Institute of Medicine (IOM) 2009 guidelines:
Pre-pregnancy BMI for typical height/weight pairs (BMI = 703 × lb / in²). Click “Use this” to pre-fill the calculator with that scenario.
| Height | Pre-pregnancy weight | Pre-pregnancy BMI | IOM category | Recommended gain | Apply |
|---|---|---|---|---|---|
| 5'4" | 110 lb | 18.9 | Normal weight | 25–35 lb | Use this → |
| 5'4" | 130 lb | 22.3 | Normal weight | 25–35 lb | Use this → |
| 5'4" | 150 lb | 25.7 | Overweight | 15–25 lb | Use this → |
| 5'4" | 175 lb | 30.0 | Obese | 11–20 lb | Use this → |
| 5'7" | 125 lb | 19.6 | Normal weight | 25–35 lb | Use this → |
| 5'7" | 145 lb | 22.7 | Normal weight | 25–35 lb | Use this → |
| 5'7" | 165 lb | 25.8 | Overweight | 15–25 lb | Use this → |
| 5'7" | 185 lb | 29.0 | Overweight | 15–25 lb | Use this → |
| 5'10" | 140 lb | 20.1 | Normal weight | 25–35 lb | Use this → |
| 5'10" | 170 lb | 24.4 | Normal weight | 25–35 lb | Use this → |
| 5'10" | 200 lb | 28.7 | Overweight | 15–25 lb | Use this → |
| 5'10" | 230 lb | 33.0 | Obese | 11–20 lb | Use this → |
IOM 2009 guidelines (reaffirmed by ACOG 2023). Singleton pregnancy; twin targets are higher.
Institute of Medicine recommendations vary by pre-pregnancy BMI and whether the pregnancy involves twins. Click “Use this” on any row to pre-fill the calculator below for that scenario.
| BMI category | Total gain | 1st trimester | Weekly after | Apply |
|---|---|---|---|---|
| Underweight (<18.5) | 28–40 lb | 1–4 lb | 1.0–1.3 lb/wk | Use this → |
| Normal (18.5–24.9) | 25–35 lb | 1–4 lb | 0.8–1.0 lb/wk | Use this → |
| Overweight (25–29.9) | 15–25 lb | 1–4 lb | 0.5–0.7 lb/wk | Use this → |
| Obese (≥30) | 11–20 lb | 1–4 lb | 0.4–0.6 lb/wk | Use this → |
| Twins (normal BMI) | 37–54 lb | 3–6 lb | 1.5 lb/wk | Use this → |
| Twins (overweight) | 31–50 lb | 3–6 lb | 1.25 lb/wk | Use this → |
IOM / NIH 2009 guidelines. Use pre-pregnancy BMI.
feet
inches
4-42 weeks
24.0
Normal weight (BMI 18.5-24.9)
25–35 lbs
~1 lb/wk in 2nd & 3rd trimester
+10.0 lbs
20.0 lbs
16 weeks left
| Pre-pregnancy BMI | Total gain (singleton) | Total gain (twins) | Weekly (2nd/3rd) |
|---|---|---|---|
| Underweight (BMI < 18.5) | 28–40 lbs | — | 1 lb/wk |
| Normal weight (BMI 18.5-24.9) | 25–35 lbs | 37–54 lbs | 1 lb/wk |
| Overweight (BMI 25-29.9) | 15–25 lbs | 31–50 lbs | 0.6 lb/wk |
| Obese (BMI ≥ 30) | 11–20 lbs | 25–42 lbs | 0.5 lb/wk |
10.0 lbs gained by week 24 — expected ~13.0 lbs
Source: Institute of Medicine, "Weight Gain During Pregnancy: Reexamining the Guidelines" (2009). This calculator is educational; individual recommendations from your OB provider may differ based on health history, multiples, or complications.
A pregnancy weight gain calculator tracks week-by-week weight gain against Institute of Medicine (IOM) 2009 guidelines for healthy total weight gain during pregnancy. Recommendations differ by pre-pregnancy BMI category (underweight, normal weight, overweight, or obese) and whether the pregnancy is singleton or twins. Our pregnancy weight gain calculator computes your pre-pregnancy BMI, classifies you into the correct IOM category, shows the recommended total gain range and weekly rate, and tracks whether your current gain is on track for where you are in your pregnancy.
Peer-reviewed studies and authoritative guidelines underlying the IOM 2009 BMI-stratified weight-gain recommendations.
Cross-checked against authoritative formulas (IRS, NIST, ACSM) and updated for 2025/2026 tax years and rates.
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Each calculator includes the formula, plain-English explanation, and FAQs so you understand the result.
Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.
FAQ
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A pregnancy weight gain calculator is a free prenatal tracking tool that compares your current weight gain to Institute of Medicine (IOM) 2009 guidelines for healthy total weight gain during pregnancy. Our pregnancy weight gain calculator takes your height, pre-pregnancy weight, current weight, current week, and singleton vs twin pregnancy, then classifies you into one of four BMI categories (underweight, normal, overweight, or obese) and shows the recommended total gain range, weekly rate, and remaining pounds needed.
How it works
Our pregnancy weight gain calculator uses your pre-pregnancy BMI to classify you into the correct IOM 2009 category and shows recommended weekly gain throughout pregnancy.
Type your height in feet and inches. The pregnancy weight gain calculator uses your height plus pre-pregnancy weight to compute pre-pregnancy BMI (kg/m²) and classify you into the correct IOM category.
Type the weight you were at before becoming pregnant (in pounds) and your current weight. The pregnancy weight gain calculator shows how many pounds you've gained so far and the IOM-recommended total gain range for your category.
Type the current week (4-42). The pregnancy weight gain calculator shows where you should be on the IOM-recommended trajectory and how many pounds remain to reach the target.
Select Singleton or Twins. IOM 2009 provides higher weight gain recommendations for twin pregnancies to support two babies. The pregnancy weight gain calculator switches to the twin guidelines table automatically.
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