It depends on your pre-pregnancy BMI. ACOG guidelines: underweight (BMI under 18.5) should gain 28-40 lbs total. Normal weight (18.5-24.9) should gain 25-35 lbs. Overweight (25-29.9) should gain 15-25 lbs. Obese (BMI 30+) should gain 11-20 lbs. Twin pregnancies have significantly higher targets.

Gestational age is counted from the first day of your last menstrual period (LMP), not the date of conception. Count the days from your LMP to today, then divide by 7 for weeks. Our gestational age calculator does this automatically and also shows your estimated due date and trimester.

These calculators use established clinical guidelines (ACOG) and provide general estimates based on standard formulas. They are useful for understanding typical ranges and tracking progress. However, every pregnancy is different and no calculator replaces the advice of your midwife, obstetrician or GP who knows your specific situation.

In the first trimester (weeks 1-12), most women gain only 1-4.5 lbs total, sometimes less. From the second trimester onward, a normal-weight woman typically gains about 0.5-1 lb per week. The exact rate varies by pre-pregnancy BMI — lighter women gain more per week; heavier women gain less.

ACOG publishes guidelines in both pounds and kilograms. Normal weight: 25-35 lbs = 11-16 kg. Overweight: 15-25 lbs = 7-11 kg. Underweight: 28-40 lbs = 13-18 kg. Obese: 11-20 lbs = 5-9 kg. Our calculator supports both units and converts automatically.

If you are significantly above or below the recommended range for your BMI category and gestational week, discuss it with your healthcare provider. Excess weight gain increases risks of gestational diabetes and C-section. Insufficient gain can affect foetal growth. Never try to lose weight intentionally during pregnancy.