Why does pre-pregnancy weight matter?

Your starting BMI determines how much reserve you have and what rate of gain best supports both maternal and fetal health throughout pregnancy.

Is it safe to diet during pregnancy?

Intentional calorie restriction during pregnancy is not recommended. Focus on nutrient-dense foods. Consult your OB or midwife for personalized guidance.

What if I gain more than recommended?

Excessive weight gain increases risks of gestational diabetes, hypertension, cesarean delivery, and postpartum weight retention. Talk to your provider if you're concerned.

What if I gain less than recommended?

Insufficient weight gain can lead to low birth weight and preterm delivery. If you're struggling to gain enough, speak with a registered dietitian.

Do these guidelines apply to twins?

No. The IOM has separate recommendations for twin pregnancies. Consult your healthcare provider for guidance specific to multiples.

Health

↵ to calculate

Pregnancy Weight Gain Calculator — BMI Weekly Gain

Find your recommended weight gain during pregnancy based on your pre-pregnancy BMI and IOM guidelines.

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How to use this calculator

👉 Fill in the boxes below and your answer appears instantly — no maths needed, we do it all for you! 🎉

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In plain English — what does this do?

🏋️ Your body needs food to move, breathe, and grow — just like a car needs petrol. This tool helps you find out how much food your body needs in a day to feel good and stay healthy!

📌 Direct Answer & Summary

The pregnancy weight gain calculator uses your pre-pregnancy Body Mass Index (BMI) to recommend a healthy total weight gain range based on guidelines from the Institute of Medicine (IOM). Gaining the right amount of weight during pregnancy supports your baby's development while reducing risks for both mother and child.

Height (cm)

Pre-pregnancy Weight (kg)

What is Pregnancy Weight Gain Calculator — BMI Weekly Gain?

How to use it

1️⃣ Enter your pre-pregnancy height and weight.
2️⃣ Choose metric (cm/kg) or imperial (in/lbs) units.
3️⃣ Your pre-pregnancy BMI and recommended total weight gain range appear instantly.

Formula

Pre-pregnancy BMI = weight(kg) / height(m)². IOM guidelines: Underweight (BMI<18.5): 12.5–18 kg. Normal (18.5–24.9): 11.5–16 kg. Overweight (25–29.9): 7–11.5 kg. Obese (≥30): 5–9 kg.

💡 See it in action — a real example

A woman who is 165 cm tall and weighs 60 kg has a pre-pregnancy BMI of 22.0 (normal weight). Her recommended total weight gain is 11.5–16 kg (25–35 lbs).

❓ Common questions

Why does pre-pregnancy weight matter?: Your starting BMI determines how much reserve you have and what rate of gain best supports both maternal and fetal health throughout pregnancy.
Is it safe to diet during pregnancy?: Intentional calorie restriction during pregnancy is not recommended. Focus on nutrient-dense foods. Consult your OB or midwife for personalized guidance.
What if I gain more than recommended?: Excessive weight gain increases risks of gestational diabetes, hypertension, cesarean delivery, and postpartum weight retention. Talk to your provider if you're concerned.
What if I gain less than recommended?: Insufficient weight gain can lead to low birth weight and preterm delivery. If you're struggling to gain enough, speak with a registered dietitian.
Do these guidelines apply to twins?: No. The IOM has separate recommendations for twin pregnancies. Consult your healthcare provider for guidance specific to multiples.

⚡ Related Health Tools & Calculators

BMI Calculator Due Date Calculator Pregnancy Calculator