Pregnancy weight gain calculator

Compare your weight gain to recommended ranges based on pre-pregnancy BMI, gestational week and singleton/twin pregnancy. Informational estimate.

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Indicative estimate

Compare your current pregnancy weight gain with the recommended ranges based on your pre-pregnancy BMI, gestational week and pregnancy type. The calculator follows Institute of Medicine (IOM) guidance for singleton and twin pregnancies.

Step 1 · Baseline measurements

Enter a value between 120 and 210 cm.

Step 2 · Current situation

You can add decimals to reflect extra days.

Recommendations come from IOM guidance for uncomplicated pregnancies.

No data is stored. Results are indicative only.

No result yet

Enter your data to see where you stand.

This tool is informational only and does not replace medical advice.

  • Pre-pregnancy BMI -- --
  • Week used --
  • Current gain --
  • Recommended range today --
  • Total target -- —
  • Suggested pace to stay on track --

How much weight should I gain during pregnancy?

Institute of Medicine (IOM) guidelines show that the ideal gain depends on your starting BMI. This pregnancy weight gain calculator summarizes the singleton targets and flags when you leave the recommended range.

Total goals for singleton pregnancies:

  • Underweight (< 18.5): 12.5 – 18 kg.
  • Healthy weight (18.5–24.9): 11.5 – 16 kg.
  • Overweight (25–29.9): 7 – 11.5 kg.
  • Obesity (≥ 30): 5 – 9 kg.

The total includes roughly 0.5 to 2 kg in the first trimester plus a steady pace from week 14 onwards.

Pregnancy weight gain calculator by BMI

The tool combines your height, starting weight, current weight and gestational week to estimate pre-pregnancy BMI and place you in the right category. It then compares your real gain with the IOM tables and labels it as below, within or above range.

This customizable pregnancy weight gain calculator lets you switch metric or imperial units, choose singleton or twin pregnancies and instantly see how many kilos you need to reach the goal. All calculations happen locally in your browser.

Recommended week-by-week weight gain

To provide a week-by-week view, the system adds the baseline first-trimester gain and, from week 14, applies indicative weekly rates for each BMI category. That way you can track your pregnancy weight by week without manual math.

  • Underweight: 0.45 – 0.59 kg/week.
  • Healthy weight: 0.36 – 0.45 kg/week.
  • Overweight: 0.23 – 0.32 kg/week.
  • Obesity: 0.18 – 0.27 kg/week.

The results panel highlights the ideal cumulative gain for your exact week and suggests a pace to stay within range.

Twin pregnancy: recommended weight gain

Selecting the twin pregnancy mode widens the range because of extra blood volume, amniotic fluid and fetal mass. The algorithm applies the dedicated IOM guidance for twin gestations so your twin pregnancy weight gain calculator remains accurate.

  • Underweight: 16.8 – 24.5 kg total.
  • Healthy weight: 16.8 – 24.5 kg.
  • Overweight: 14 – 23 kg.
  • Obesity: 11 – 19 kg.

The panel shows how far you are from the lower and upper limits and reminds you to discuss any deviation with your care team.

Frequently asked questions

What is the recommended pregnancy weight gain?

It depends on BMI: 12.5–18 kg if you started underweight, 11.5–16 kg for a healthy BMI, 7–11.5 kg for overweight and 5–9 kg for obesity. The calculator returns the exact target for your profile.

How can I calculate my ideal pregnancy weight gain?

Enter your height, pre-pregnancy weight, current weight and gestational week. The tool estimates your starting BMI and compares your gain with the appropriate IOM range.

Is weight gain different with a twin pregnancy?

Yes. Twin pregnancies call for roughly 11 to 24.5 kg depending on BMI. Switch to “twin pregnancy” to see the adjusted range and suggested pace.

How many kilos should I have at week X of pregnancy?

The calculator provides a personalized week-by-week range, showing whether your cumulative gain for that week is below, within or above the target interval.

How do I calculate pregnancy weight by BMI?

We classify your starting BMI (underweight, healthy, overweight or obesity) and apply the IOM goals for that tier to estimate both the total gain and the suggested weekly pace.

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