Breastfeeding Calorie Calculator

This breastfeeding calorie calculator estimates how many calories you need each day while you are nursing or pumping. Enter your age, height, weight and activity level, then tell it how old your baby is and how much of their milk comes from you. You get three numbers: what your body would need without breastfeeding, the extra energy that making milk costs, and a sensible target if you want to lose weight slowly.

Treat the result as a starting point, not a rule. Your appetite, energy levels and milk supply are better guides than any formula. To understand where the extra energy goes, read how many calories breastfeeding burns, and for what to put on your plate, see our breastfeeding nutrition and health guide.

How the calculator works

The calculation has three steps.

1. Your resting energy (BMR). We use the Mifflin-St Jeor equation for women, a widely used formula based on measurements in 498 healthy adults (Mifflin, 1990):

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

2. Your activity. The BMR is multiplied by an activity factor: 1.2 if you mostly sit, 1.375 if you are lightly active, 1.55 if you exercise 3 to 5 days a week and 1.725 if you are very active. These are commonly used multipliers, not official values, and our choice for this calculator. The result is what you would need to maintain your weight if you weren’t breastfeeding.

3. The energy cost of making milk. We use the National Academies’ 2023 Dietary Reference Intakes for Energy (energy cost of milk production minus the energy mobilized from body stores):

Baby’s age	Energy cost of making milk	Energy from your body’s stores	Extra calories from food
0–6 months, exclusive breastfeeding	540 kcal/day	140 kcal/day	+400 kcal/day
7–12 months (with solid foods)	380 kcal/day	none counted	+380 kcal/day

The older 2005 figures (+330 and +400 kcal a day) are still quoted by the CDC and the Dietary Guidelines for Americans, so you may see them elsewhere.

If your baby also gets formula, the calculator scales the milk energy by the share of breast milk you choose (all, about three quarters, half or a quarter). That scaling is our own simplification.

Gradual weight loss. The weight-loss figure is your total minus 500 kcal a day, which works out to roughly 1 pound (0.5 kg) a week, the pace the Academy of Nutrition and Dietetics calls a safe goal. It never goes below 1,800 kcal a day, because eating less may reduce your milk supply.

Worked examples

Example	Inputs	Result
First months, light activity	30 years, 5 ft 5 in, 150 lb, lightly active, baby 0–6 months, all breast milk	BMR ≈ 1,400 · without breastfeeding ≈ 1,930 · total ≈ 2,330 kcal/day · weight loss ≈ 1,830
More active	Same, but exercising 3–5 days a week	Without breastfeeding ≈ 2,170 · total ≈ 2,570 kcal/day · weight loss ≈ 2,070
Older baby, partly breastfed	Same as the first example, baby 7–12 months, about half breast milk	Extra ≈ +190 · total ≈ 2,120 kcal/day · weight loss: 1,800 (minimum)

How to read your result

• It’s an estimate. Formulas like this can be off for an individual. If you are always hungry, eat more; if you are steadily gaining weight you didn’t want to gain, eat a little less.
• Hunger is normal. Many people feel hungrier while breastfeeding, especially in the first months. Keep easy, nourishing snacks within reach.
• Quality matters as much as quantity. Protein, whole grains, fruit, vegetables and enough fluids help you feel well. Many parents are advised to keep taking a prenatal or breastfeeding vitamin; ask your provider what’s right for you.
• Don’t rush weight loss. Wait until breastfeeding is going well and aim for slow, steady loss. A sudden drop in calories can leave you exhausted.

Who this calculator is not for

The formula is designed for healthy adults. It is not accurate if you are under 18, have a medical condition that affects your metabolism (such as a thyroid condition), are breastfeeding twins or more, are pregnant again, or are recovering from a complicated birth. In those cases, ask your doctor or a registered dietitian for a personal plan.

If you are worried that low calories might be affecting your milk, see our guide on how to increase milk supply, and talk to a lactation consultant.