Find out exactly how many extra calories you need during each trimester of pregnancy, plus protein and key nutrient recommendations.
Calculate Now ↓Based on pre-pregnancy weight and activity. Calorie additions are based on NICE and WHO guidelines.
During the first trimester, calorie needs barely increase. The embryo is tiny and the energy demands are minimal. Focus on quality rather than quantity — folate, iron, and iodine are especially important.
The second trimester sees significant foetal growth. An additional 300 kcal per day is recommended. This is when the baby develops bones, muscles, and organs most rapidly.
Energy needs peak in the third trimester as the baby gains the most weight. An additional 450 kcal per day supports the final stages of development and prepares the body for birth.
Breastfeeding requires an additional 400–500 kcal per day above pre-pregnancy needs. Protein needs also remain elevated at around 1.1g/kg of body weight.
This calculator starts by estimating your pre-pregnancy TDEE (total daily energy expenditure) using standard calorie formulas, then adds trimester-specific calorie increases based on guidance from the American College of Obstetricians and Gynecologists (ACOG) and the WHO: roughly no increase in the first trimester, about 300 extra kcal/day in the second, and about 450 extra kcal/day in the third, since foetal growth accelerates significantly in the final months.
These are population averages, not individual medical guidance. Healthy weight gain during pregnancy also depends heavily on your pre-pregnancy BMI — the Institute of Medicine recommends higher total weight gain for those starting underweight and lower gain for those starting with a higher BMI. Multiple pregnancies (twins or more), pre-existing conditions like gestational diabetes, and morning sickness affecting intake all change these numbers substantially. This calculator is meant to support, not replace, your prenatal care team's individualised guidance.