Fill in the details and click Calculate to see your results.
![Weight Gain formula: BMI = Weight (kg) ÷ [Height (m)]²; Set by your BMI category (see table below)](https://powercalculators.com/assets/img/calculators/pregnancy-weight-gain-calculator-1200x630.jpg?v=f3423a8712 "Pregnancy Weight Gain Calculator — formula explained")
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How much weight to gain in pregnancy depends on your BMI before you became pregnant. This calculator uses the Institute of Medicine's 2009 guidelines, the standard used by doctors and midwives, to show your healthy range.
Enter your pre-pregnancy weight, height and the first day of your last period to see your recommended total gain and how much you would be expected to have gained by now.
| Pre-Pregnancy Weight | 50 kg |
| Height | 160 cm |
| First Day of Last Menstrual Period | 1 May 2026 |
| Recommended total weight gain | 11.5 – 16 kg |
| Pre-pregnancy BMI | 19.5 (Normal weight) |
| Target weight at delivery | 61.5 – 66 kg |
| Weekly gain in 2nd & 3rd trimester | 0.35 – 0.5 kg a week |
| Healthy gain by now (week 25) | 6.2 – 8 kg |
| Your weight should be about | 56.2 – 58 kg now |
Recommended gain 11.5 – 16 kg; target weight 61.5 – 66 kg.
Try this example →| Pre-Pregnancy Weight | 85 kg |
| Height | 160 cm |
| First Day of Last Menstrual Period | 1 May 2026 |
| Recommended total weight gain | 5 – 9 kg |
| Pre-pregnancy BMI | 33.2 (Obese) |
| Target weight at delivery | 90 – 94 kg |
| Weekly gain in 2nd & 3rd trimester | 0.17 – 0.27 kg a week |
| Healthy gain by now (week 25) | 2.5 – 3.7 kg |
| Your weight should be about | 87.5 – 88.7 kg now |
Recommended gain 5 – 9 kg.
Try this example →A single week outside the range is not unusual — fluid retention and appetite vary. A consistent trend away from the range is worth discussing with your doctor.
No. Twin pregnancies have their own, higher recommended ranges. This calculator is for a single baby.
Weight gain in the first trimester is mostly maternal — the baby is still tiny. Growth accelerates in the second and third trimesters, which the weekly rate reflects.
11.5–16 kg if your BMI before pregnancy was normal; more if underweight, less if overweight.
Only about 0.5–2 kg in the first 13 weeks; most gain happens after that.