Pregnancy calories calculator
Enter your height, weight and week: get the calories per day now and the extra over before pregnancy.
For general information only — not medical advice. This is a population estimate for a single pregnancy; it does not replace the advice of your prenatal provider or a registered dietitian, especially if you have diabetes, a multiple pregnancy, an eating disorder or a high-risk pregnancy. How we check our calculators.
Use the weight you had before pregnancy to find your BMI category. Leave “weight now” empty to use that weight (the estimate is then slightly low after the first trimester).
What the number means
The result is an estimated energy requirement (EER): the average number of calories per day that keeps a healthy woman of your age, height, weight and activity level in energy balance, including, during pregnancy, the energy to build the baby, placenta and your own tissues, and, while breastfeeding, the energy in the milk. It is an average for people like you. The report is plain that individual needs vary considerably around it, which is why it pairs the estimate with advice to watch your weight over time. The extra shown is the difference between the estimate now and the estimate for the same woman before pregnancy.
The method
Before pregnancy and in the first trimester (up to 13 completed weeks), the National Academies equation for a woman 19 or older is EER = a − b₁ × age + b₂ × height (cm) + b₃ × weight (kg), where the four constants depend on the activity level; for “active” it is 710.25 − 7.01 × age + 6.54 × height + 12.34 × weight. From week 14 the pregnancy equation applies: for “active”, EER = −223.84 − 2.04 × age + 13.23 × height + 8.15 × weight + 9.16 × weeks + a tissue allowance of +300 (BMI under 18.5), +200 (18.5 to under 25), +150 (25 to under 30) or -50 (30 and over), using your weight before pregnancy to find the BMI and your weight now in the equation. Each activity level has its own constants. While breastfeeding the non-pregnant equation is used with your current weight, plus 540 − 140 = 400 kcal for exclusive breastfeeding up to 6 months or plus 380 kcal for partial breastfeeding from 7 to 12 months.
A worked example
The report itself works out a woman aged 28, 170 cm tall (5 ft 7 in), active, weighing 65 kg (143 lb) before pregnancy, with a healthy BMI, and gaining weight at the recommended rate. In the first trimester her estimate is 2,428 kcal. At week 20 and 69 kg (152 lb) it is 2,914 kcal, which is 486 more; at week 32 and 75 kg (165 lb) it is 3,073 kcal, 645 more. (The report prints 2,428, 2,914 and 3,072: the same numbers to within a calorie of rounding.) Under the older rule she would add 340 and 452. Breastfeeding at 65 kg, the same woman’s estimate is 2,828 kcal at 3 months (2,428 + 400) and 2,808 kcal at 9 months.
Common mistakes
“Eating for two.” The extra need is a few hundred calories in the second and third trimesters and none in the first; it is nowhere near doubling. The report treats gaining the expected amount of weight as the sign that energy intake is adequate.
Using today’s weight to find the BMI category. The tissue allowance is chosen from the BMI before pregnancy. Using your current weight can put you in the wrong category and change the allowance by 50 to 200 kcal for each category you are off.
Adding the extra to a guess. The extra calories are added to your requirement, not to a generic 2,000 calories. A tall, active woman and a short, inactive one have very different baselines.
Limits of this method
It describes averages of studies of healthy women. The report says more measurements of pregnant women across all BMI categories are needed, particularly to learn the needs of women who gained within and outside the recommended range. Treat the result as a place to start.
It does not cover everyone. The equations on this page are for women 19 and older with a single pregnancy; pregnant teenagers have their own equations in the report, and we found nothing on twins. Women with diabetes, eating disorders, hyperemesis or other conditions have clinical plans that override a formula.
The activity categories are fuzzy. The report says that at present a valid, reliable tool to classify an individual’s activity category does not exist.
The older and newer numbers differ. If your provider or an app quotes +340 and +450, that is the 2005 IOM rule, which the table in the result shows for comparison.
How many extra calories do I need during pregnancy?
The widely quoted rule, from the 2005 Institute of Medicine energy report, is no extra calories in the first trimester, about 340 more per day in the second and about 452 more in the third, for a woman who started at a normal weight. The 2023 National Academies update, which this calculator follows, no longer gives one number: it adds an allowance for tissue growth that depends on your weight before pregnancy (+300 kcal if underweight, +200 if healthy weight, +150 if overweight and -50 if you have obesity) on top of the energy your own body now uses. For the example woman below that comes to about 486 more calories at week 20 and 645 more at week 32.
Do I need extra calories in the first trimester?
No. The National Academies use the non-pregnant equation for the first trimester, defined as conception through 13 completed weeks, because weight gain and tissue growth are small and the energy for them is considered negligible. The older IOM guidance says the same: no extra calories are usually needed in the first trimester. Nausea and food aversions can make eating enough the problem, not eating too much, and that is a reason to talk to your prenatal provider.
Why do the 2023 numbers differ from the 340 and 450 rule?
The 2005 report built its numbers from three pieces: the non-pregnant requirement, 8 kcal per week of pregnancy of extra energy expenditure (measured in four studies), and 180 kcal a day for growth of maternal and fetal tissue. At week 20 that is 160 + 180 = 340, and at week 34 it is 272 + 180 = 452. The 2023 committee rebuilt the equations from a database of doubly labeled water measurements of total energy expenditure, made the expenditure depend on your current weight and week, and made the tissue allowance depend on your pre-pregnancy BMI because the tissue deposited differs with BMI. As a result individual estimates can be larger or smaller than 340 and 452, which is why the table in the result shows both.
How many extra calories do I need while breastfeeding?
The National Academies equations add the energy cost of the milk and subtract the energy taken from the mother’s body stores. In the first 6 months of exclusive breastfeeding that is 540 kcal of milk minus 140 kcal from body stores, about +400 kcal a day (the report text rounds the net to 404). From 7 to 12 months of partial breastfeeding, with the baby also eating other foods, it is 380 kcal, which assumes your weight is stable. The older 2005 figures were +330 and +400. Your own need can be very different: the report stresses monitoring your weight and adjusting.
Does the calculator work for twins?
No. The National Academies equations were built from studies of women with a single baby, and we found no twin-specific energy figure in the report. If you are carrying twins or more, ask your prenatal provider or a registered dietitian for a plan; weight-gain targets for twins are on our pregnancy weight gain calculator.
I am overweight or have obesity. Do I still add calories?
The tissue allowance falls with BMI: +150 kcal for overweight and -50 kcal for obesity in the second and third trimesters, so your estimate rises less, or not at all, compared with a woman who started at a healthy weight. The old IOM statement says the same in words: if you are overweight or obese, you may need fewer extra calories. This is a planning estimate: the report’s own advice is to monitor weight gain against the recommended range for your BMI (see the pregnancy weight gain calculator) and adjust intake, together with your provider.
Should I count calories during pregnancy?
Not as a rule. The National Academies describe the estimate as the first step of a two-step process: calculate an estimate, then monitor your body weight over time and adjust. For growing children and pregnant women, they say, meeting the energy requirement is reflected by gaining the expected amount of weight over time. The estimate on this page is useful for knowing the scale of the change in needs; the weight-gain curve and your provider’s advice are the real feedback.
What activity level should I choose?
The report has four categories (inactive, low active, active, very active) set from roughly the quartiles of measured activity in the studies behind the equations, so they describe how much energy people actually used, not whether you meet exercise guidelines. “Inactive” does not mean fully sedentary: it means minimally active beyond daily living with little or no occupational activity. The report admits there is no reliable tool for putting one person into a category. Pick the closest, and judge the result against your weight and hunger.
More for pregnancy: the pregnancy weight gain calculator, the due date calculator, the pregnancy week calculator, the calorie calculator, the protein calculator and the BMI calculator.
Sources, read October 27–28, 2026: National Academies of Sciences, Engineering, and Medicine, Dietary Reference Intakes for Energy (2023), Summary, Tables S-3 to S-6, and chapter 7, “Applications of the Dietary Reference Intakes for Energy,” Box 7-1, doi 10.17226/26818 (equations, tissue allowance by BMI, lactation costs, activity categories); Redman L, “Energy Requirements to Support Pregnancy Weight Gain and Lactation at Varying BMIs,” National Academies workshop slides, March 31, 2022 (the 2005 IOM Dietary Reference Intakes, chapter 5, and the 2009 IOM Weight Gain During Pregnancy report: 0, +340 and +452 kcal; +330 and +400 kcal while breastfeeding). This calculator is not endorsed by or affiliated with the National Academies.
For general information only — not medical advice. Talk with your prenatal provider or a registered dietitian about how much you should eat. How we check our calculators.