Pregnancy Weight Gain Calculator
Check pregnancy weight gain against IOM guidelines using your pre-pregnancy BMI — week by week, trimester by trimester.
Recommended total gain
11.5–16 kg
For Normal weight (BMI 22.1)
Your gain so far
7 kg
Outside the recommended range
Remaining gain budget
4.5–9 kg
Recommended, not a target
2nd/3rd trimester pace
≈ 0.4 kg/week
Typical weekly gain guideline
Based on the IOM pregnancy weight-gain guidelines, which depend on pre-pregnancy BMI. Every pregnancy differs — follow your doctor's advice over any calculator output.
Last updated: June 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Use the pregnancy weight gain calculator at each antenatal milestone to see how your weight is tracking against the IOM guidelines for your pre-pregnancy BMI. It is most valuable around the second and third trimesters, when gain accelerates and the weekly pace becomes meaningful. Rather than chasing a number, treat the range as a conversation starter: if you are consistently above or below it, you have a clear point to raise with your doctor about diet, activity and what is typical in your situation. The tool is also useful before pregnancy, to see which BMI category you would start from and what the guidelines would expect. It is general educational guidance, not a prescription — multiple pregnancies, health conditions and individual advice always override a calculator range.
How to Use This Calculator
- Step 1: Enter your pre-pregnancy weight in kilograms.
- Step 2: Enter your height in centimetres so the calculator can work out your BMI category.
- Step 3: Add your current week of pregnancy and your weight today.
- Step 4: Compare your gain so far with the recommended range and weekly pace shown.
Worked Example
A woman in Pune weighed 58 kg before pregnancy and is 162 cm tall, giving a pre-pregnancy BMI of 22.1 — a normal starting weight. At week 20 she weighs 65 kg, a gain of 7 kg so far. The calculator shows the IOM range for her category is 11.5–16 kg total, with a typical second-half pace of about 0.42 kg per week, so her remaining gain budget is roughly 4.5–9 kg. Since 7 kg sits below 11.5 kg, she is currently outside the guideline range and her doctor will want to review her diet and weight at the next visit.
Tips and Common Mistakes
- •Tip 1: Weigh yourself on the same scale at the same time of day for consistent comparisons.
- •Tip 2: Focus on nutrient-dense foods — dal, eggs, paneer, fruits and vegetables — rather than eating for two in quantity.
- •Tip 3: Gain is naturally slow in the first trimester and faster later, so judge your trend over weeks, not days.
- ✗Mistake 1: Dieting to lose weight during pregnancy — it can harm the baby's growth and should never be done without medical advice.
- ✗Mistake 2: Panicking about being slightly over the range; hydration and weighing conditions easily explain 1–2 kg swings.
Frequently Asked Questions
What weight gain is recommended in pregnancy?
Under the IOM guidelines, women who start at a normal BMI (18.5–24.9) are advised to gain about 11.5–16 kg in total. Underweight women aim for 12.5–18 kg, overweight for 7–11.5 kg and obese for 5–9 kg.
Why does the recommendation depend on my pre-pregnancy BMI?
The mother's body reserves differ with BMI, so the extra energy and weight needed for a healthy baby differ too. The guidelines aim to balance the baby's growth with the mother's risk of complications like gestational diabetes.
My gain is above the range — should I diet?
No. Never diet or restrict food during pregnancy without medical advice. Weight gain is naturally uneven, with little gain in the first trimester and faster gain later. Discuss any concerns with your doctor.
What does the weekly pace in the second half mean?
From the second trimester onward, steady gain of roughly 0.4 kg per week is typical for normal-BMI women (0.5 for underweight, 0.3 for overweight, 0.2 for obese). It is a general guide, not a strict target.
Do twins or multiple pregnancy change the range?
Yes, recommended gains are higher for twins — about 17–25 kg for normal-BMI women. This calculator shows singleton-pregnancy guidance; your doctor will advise the right range for a multiple pregnancy.
Compare these tools
- BMI Calculator — Calculate your Body Mass Index instantly and see your WHO weight category
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