Pregnancy Calorie Calculator
Daily calorie target in pregnancy from pre-pregnancy weight, height, age, activity, and trimester.
What it does
Pregnancy changes energy needs, but not as much as the old advice about eating for two suggests. A person needs extra calories to build blood, placenta, and fetal tissue, and to carry the added weight. The total depends on the starting body size, age, activity, and how far along the pregnancy is.
This calculator starts with the Mifflin-St Jeor equation, the resting energy formula used in dietetics for adults. For women the equation is 10 times weight in kilograms plus 6.25 times height in centimeters minus 5 times age minus 161. That gives basal metabolic rate, the energy used at complete rest.
Basal rate is then multiplied by an activity factor between 1.2 and 1.725. The result is the maintenance calories the person would need outside pregnancy. The trimester addition goes on top: none in the first trimester, about 340 calories in the second, and about 450 in the third, following the federal dietary guidance for pregnancy.
A 30 year old who is 165 cm tall and weighed 68 kg before pregnancy, with moderate activity, has a resting rate near 1,400 and a maintenance level near 2,170. In the second trimester the estimate is about 2,510 calories a day. That is a target for planning meals, not a strict daily quota.
Weight gain guidance is a separate question. The Institute of Medicine ranges, summarized by ACOG, depend on pre-pregnancy body mass index: about 25 to 35 pounds for a normal BMI, less for a higher BMI, and more for a low BMI. Calorie counts and weight gain targets should be set together with a clinician.
How to use
- Choose metric or imperial units and enter height in the matching field.
- Enter the weight you had just before conception, not the current weight.
- Add your age in years and pick the activity level that matches a normal week.
- Select the trimester you are in now.
- Read the daily target, then check the maintenance figure and the trimester addition beside it.
- Recheck the estimate each trimester, since the addition rises as the pregnancy progresses.
Formula
- W
- Pre-pregnancy weight in kilograms.
- H
- Height in centimeters.
- A
- Age in years.
- activity
- Activity multiplier: 1.2, 1.375, 1.55, or 1.725.
- addition
- Extra calories for the trimester: 0, 340, or 450.
Imperial inputs are converted with 2.54 cm per inch and 0.45359237 kg per pound, so both systems return the same result. The equation is for adult women and does not apply to twins, teens, or people with thyroid disease or other conditions that change energy use. A clinician may adjust the target for pre-pregnancy BMI, weight gain so far, and medical history.
Worked example
Example: 30 years old, 165 cm, 68 kg, moderate activity, second trimester
Metric defaults: age 30, height 165 cm, pre-pregnancy weight 68 kg, activity 1.55, second trimester.
- Weight term: 10 x 68 = 680.
- Height term: 6.25 x 165 = 1,031.25.
- Age term: 5 x 30 = 150. Then subtract the constant: 680 + 1,031.25 - 150 - 161 = 1,400.25 kcal.
- Maintenance: 1,400.25 x 1.55 = 2,170.39 kcal.
- Second trimester addition: 340 kcal.
- Daily target: 2,170.39 + 340 = 2,510.39, shown as 2,510 kcal per day.
Reference table
| Activity level | Maintenance | Addition | Daily target |
|---|---|---|---|
| Sedentary (1.2) | 1,680 kcal | +340 | 2,020 kcal |
| Light (1.375) | 1,925 kcal | +340 | 2,265 kcal |
| Moderate (1.55) | 2,170 kcal | +340 | 2,510 kcal |
| Very active (1.725) | 2,415 kcal | +340 | 2,755 kcal |
Limits
- Built for one adult with a singleton pregnancy, not twins or higher order pregnancies.
- Uses pre-pregnancy weight and does not adjust for weight already gained.
- Assumes no medical condition that changes energy needs, such as thyroid disease or gestational diabetes.
- Activity multipliers are broad averages; actual energy use varies between people.
Common mistakes
- Entering the current pregnancy weight, which raises the estimate and hides the original baseline.
- Applying the third trimester addition for the whole pregnancy.
- Choosing a high activity level for a normal week that includes only light walks.
- Treating the calorie target as a minimum that must be eaten every day.
- Ignoring weight gain guidance and focusing on calories alone.
Try it yourself
Quick checks. Answers sit tucked under each question.
28 years old, 170 cm, 75 kg, moderate activity, third trimester?
BMR 1,512 kcal/day, maintenance 2,343 kcal/day, addition +450 kcal/day, target 2,793 kcal/day.
35 years old, 5 ft 4 in, 140 lb, light activity, first trimester?
BMR 1,315 kcal/day, maintenance 1,808 kcal/day, addition +0 kcal/day, target 1,808 kcal/day.
30 years old, 165 cm, 68 kg, sedentary, second trimester?
BMR 1,400 kcal/day, maintenance 1,680 kcal/day, addition +340 kcal/day, target 2,020 kcal/day.
Questions
How many extra calories do I need in pregnancy?
Federal guidance adds no extra calories in the first trimester, about 340 a day in the second, and about 450 a day in the third.
Should I eat for two?
No. The extra need is a few hundred calories, not a second adult portion. The second trimester addition is roughly a snack plus a small meal component.
Why use pre-pregnancy weight?
The equation predicts energy use for a stable body size. Using the current weight mixes in the pregnancy itself and overstates the baseline.
Does this work for twins?
No. Twin pregnancies need more energy and different weight gain targets, which a clinician should set.
Can I diet during pregnancy?
Restrictive dieting is not advised without medical supervision. Focus on food quality and appropriate weight gain rather than cutting calories.
How accurate is the estimate?
It is a population formula with a margin of error of roughly 10%. Use it as a starting point and adjust with your clinician based on weight gain and how you feel.
Sources
- Office of Disease Prevention and Health Promotion: Eat healthy during pregnancy
- ACOG: How much weight should I gain during pregnancy?
- PubMed: A new predictive equation for resting energy expenditure (Mifflin and St Jeor)