What This Calculator Does
The Pregnancy Calorie Needs Calculator estimates how many calories you may need per day during pregnancy. It first calculates your maintenance energy needs (TDEE) from your pre-pregnancy body stats and activity level, then adds the extra energy your body needs to support a healthy pregnancy based on your current trimester. This is general educational guidance and not medical advice — always follow the recommendations of your doctor, midwife, or registered dietitian, especially if you have a high-risk pregnancy, are carrying multiples, or have a condition such as gestational diabetes.
How to Use It
Choose your activity level, select your trimester, and enter your pre-pregnancy weight (kg), height (cm), and age. The calculator returns your estimated daily calorie target along with your BMR, maintenance TDEE, and the pregnancy add-on so you can see exactly how the number is built up.
The Formula Explained
We use the Mifflin-St Jeor equation for women: $$\text{BMR} = 10 \times \text{weight} + 6.25 \times \text{height} - 5 \times \text{age} - 161$$. BMR is multiplied by an activity factor (1.2 to 1.9) to get TDEE, your maintenance calories. Finally a trimester add-on is applied: +0 kcal in the first trimester, +340 kcal in the second, and +452 kcal in the third. These add-ons reflect widely cited estimates of the extra energy required to support fetal growth and maternal tissue changes.
Worked Example
A 30-year-old woman who is 165 cm tall and weighed 65 kg before pregnancy, lightly active (factor 1.375), in her second trimester: $$\text{BMR} = 10 \times 65 + 6.25 \times 165 - 5 \times 30 - 161 = 650 + 1031.25 - 150 - 161 = 1370.25 \text{ kcal}$$ $$\text{TDEE} = 1370.25 \times 1.375 \approx 1884.1 \text{ kcal}$$ Adding the second-trimester +340 gives about 2,224 calories/day.
FAQ
Do I really "eat for two"? No. Calorie needs increase only modestly — typically a few hundred extra calories per day in the second and third trimesters, not double.
Why is the first-trimester add-on zero? Energy needs change very little in early pregnancy, so most guidelines recommend no extra calories during the first trimester for most women.
Is this accurate for twins or underweight/overweight women? No — those situations need individualized advice. Use this only as a rough starting estimate and consult your healthcare provider.
