Pregnancy Weight Gain Calculator
Determine healthy, evidence-based weight gain target ranges and weekly rates based on pre-pregnancy BMI guidelines.
Calculate Recommended Weight Gain
Enter your height, pre-pregnancy weight, and pregnancy type.
IOM Clinical Weight Gain Reference Table
| Pre-Pregnancy BMI Category | BMI Range | Singleton Total Gain | Twins Total Gain |
|---|---|---|---|
| Underweight | < 18.5 | 12.5 – 18.0 kg (28–40 lbs) | Clinical consultation |
| Normal Weight | 18.5 – 24.9 | 11.5 – 16.0 kg (25–35 lbs) | 17.0 – 25.0 kg (37–54 lbs) |
| Overweight | 25.0 – 29.9 | 7.0 – 11.5 kg (15–25 lbs) | 14.0 – 23.0 kg (31–50 lbs) |
| Obese | ≥ 30.0 | 5.0 – 9.0 kg (11–20 lbs) | 11.0 – 19.0 kg (25–42 lbs) |
When to See a Doctor
Online calculators provide general estimates based on biological averages. Consult a healthcare provider (such as an OB/GYN or general practitioner) if you notice:
- Your periods suddenly become irregular after being consistent
- Your cycle is consistently shorter than 21 days or longer than 35 days
- Your period bleeding lasts longer than 7 days or is unusually heavy (soaking through a pad/tampon every hour)
- You experience severe, debilitating pelvic pain or cramping that disrupts daily life
- You experience bleeding between periods or after intercourse
- You are under 35 and have been trying to conceive for 12 months (or 6 months if 35+)
- Your period has stopped completely for 90 days or more (and you are not pregnant)
Frequently Asked Questions
Evidence-based answers to common questions about your cycle and fertility.
How much weight should I gain during pregnancy?
Per IOM/ACOG guidelines for singleton pregnancies: Underweight (BMI <18.5): 28–40 lbs (12.5–18 kg); Normal weight (BMI 18.5–24.9): 25–35 lbs (11.5–16 kg); Overweight (BMI 25–29.9): 15–25 lbs (7–11.5 kg); Obese (BMI ≥30): 11–20 lbs (5–9 kg).
How is weight gained across trimesters?
In the first trimester, total weight gain is typically small (1 to 4.5 lbs / 0.5 to 2 kg). In the second and third trimesters, weight gain progresses at a steady weekly rate (approximately 0.5 to 1 lb / 0.2 to 0.5 kg per week depending on BMI).
Pregnancy Calorie Calculator
Calculate your daily energy and calorie needs by trimester using the Mifflin-St Jeor formula and activity level guidelines. 100% private.
Due Date Calculator
Calculate your estimated baby due date, current gestational age, trimester, and weekly milestones from your LMP, conception, or ultrasound date.
Pregnancy Week Calculator
Calculate how many weeks and days pregnant you are today, identify your current trimester, and view baby developmental milestones.
Medical & Scientific Sources
- Institute of Medicine (IOM) / National Academies(2009). "Weight Gain During Pregnancy: Reexamining the Guidelines"
- American College of Obstetricians and Gynecologists (ACOG)(2016). "ACOG Practice Bulletin No. 156: Obesity in Pregnancy"