Get personalized daily calorie targets for each trimester based on your body stats and activity level.
Enter your pre-pregnancy weight, height, age, and typical activity level, then select your current trimester. Click "Calculate My Caloric Needs" to see your personalized daily calorie target, macronutrient breakdown, and how your needs change across all three trimesters. You can switch between trimester tabs to compare nutritional requirements throughout your pregnancy journey.
Caloric needs during pregnancy aren't simply "eating for two" — the actual additional energy needed is more nuanced and varies significantly by trimester. Research from the Institute of Medicine shows that most women need zero extra calories in the first trimester, approximately 340 extra calories per day in the second trimester, and roughly 450 extra calories per day in the third trimester.
Undereating during pregnancy can limit fetal growth and brain development, increase risk of preterm birth, and deplete maternal nutrient stores. Overeating, on the other hand, raises gestational diabetes risk, increases likelihood of cesarean delivery, and can complicate postpartum weight management.
For example, a moderately active 28-year-old woman at 145 lbs and 5'6" has a baseline TDEE of roughly 2,050 calories/day. In her second trimester, that increases to ~2,390 calories/day. Getting those numbers right — and targeting the right mix of protein, carbs, and fats — is one of the most impactful things you can do for your baby's development.
This calculator uses the Mifflin–St Jeor equation, the most clinically validated formula for estimating resting metabolic rate (RMR) for women:
RMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
The RMR is then multiplied by an activity factor (1.2 for sedentary up to 1.9 for extra active) to get your Total Daily Energy Expenditure (TDEE). Trimester-specific calorie additions are then applied based on IOM guidelines: +0 kcal (1st), +340 kcal (2nd), +452 kcal (3rd).
Macronutrients are estimated using standard pregnancy nutrition guidelines: approximately 20–25% of calories from protein, 50–55% from carbohydrates, and 25–30% from healthy fats — with minimum floors for protein (71g/day recommended by IOM) and carbohydrates (175g/day) during pregnancy.
No — in the first trimester, most women need virtually no additional calories above their pre-pregnancy baseline. The fetus grows very little in weeks 1–12, and extra calorie demands are minimal. It's only from the second trimester onward that meaningful increases (340–452 kcal/day) are recommended by clinical guidelines.
This calculator is designed for singleton pregnancies. Twin pregnancies typically require an additional 300–500 calories per day on top of the standard trimester additions, bringing total increases to roughly 600–800 kcal/day in the second and third trimesters. If you're carrying multiples, please work directly with a maternal-fetal medicine specialist or registered dietitian.
Light to moderate exercise is generally encouraged during uncomplicated pregnancies — it can reduce gestational diabetes risk, ease back pain, and improve mood. However, during pregnancy you should not increase exercise intensity primarily to "offset" calorie intake. The additional calories you need are for fetal development, not to be burned off. Always consult your OB before starting or maintaining an exercise routine.
The Mifflin–St Jeor equation is accurate within ±10% for most individuals, which is the best available estimate without indirect calorimetry. Individual metabolic rates can vary based on genetics, thyroid function, sleep, and pregnancy-specific adaptations. Use these results as a starting point, then adjust based on actual weight gain trajectory (typically 1–2 lbs/week in the 2nd and 3rd trimesters for normal-weight women) in consultation with your healthcare provider.