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Free pregnancy weight gain tool: we classify pre-pregnancy BMI, show recommended total gain (singleton or twin), and compare your gain so far. Pair with our pregnancy calculator for dating context—not a substitute for prenatal care.
Last updated: April 11, 2026
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Current gain
5.0 kg
Pre-pregnancy BMI
Underweight
BMI 18.4
Status
Below Recommended Range
Recommended total gain (IOM-style)
12.7 kg – 18.1 kg
~20 weeks to term (40 wk model)
Rough pace check: ~4.3 kg by week 20 (1 lb/wk model after first trimester — illustrative only)
Discuss nutrition and gain goals with your obstetric provider—this tool does not replace medical advice.
Bands
Underweight → Obese
Uses weight before pregnancy and height to mirror guideline tables.
Output
Min–max recommendation
Metric view converts pounds to kilograms with a fixed factor for consistency.
Status
Below / within / above
Compares your total gain to the full-pregnancy band for your BMI.
Toggle
Singleton vs twins
Underweight + twins uses a documented-style range where official tables are often blank.
Context
Rough pacing note
Includes an illustrative “~1 lb/week after first trimester” check—not a prescription.
Disclaimer
Clinician-led care
Comorbidities and fetal indications can change targets—always defer to your care team.
Week 20, singleton, height 165 cm, pre-pregnancy 50 kg, now 55 kg → BMI 18.4 (Underweight), gain so far 5 kg, recommended total roughly 12.7–18.1 kg, status Below Recommended Range.
We compute pre-pregnancy BMI from your entered height and pre-pregnancy weight, map it to Institute of Medicine total gestational gain ranges (in pounds), then convert to kilograms if you chose metric. Your “current gain” is simply current weight minus pre-pregnancy weight, compared to the recommended total band for your category—useful for big-picture tracking alongside fitness & lifestyle planning.
| BMI category | Recommended total |
|---|---|
| Underweight (<18.5) | 28–40 lb |
| Normal (18.5–24.9) | 25–35 lb |
| Overweight (25–29.9) | 15–25 lb |
| Obese (≥30) | 11–20 lb |
Twin pregnancies use higher totals; enable twin mode in the calculator for those bands.
Also explore due date and postpartum weight change tools when planning follow-up questions for your clinician.
Get a Custom Calculator for Your PlatformShare it with expecting parents or your care team (informational use).
Suggested hashtags: #Pregnancy #WeightGain #MaternalHealth #PregnancyHealth #Calculator