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, one of the most accurate everyday formulas:

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. This is what you would need to maintain your weight if you weren’t breastfeeding.

3. The energy cost of making milk. The Institute of Medicine’s energy requirements for lactation are:

Baby’s age	Energy in the milk you make	Energy from pregnancy fat stores	Extra calories from food
0–6 months, exclusive breastfeeding	about 500 kcal/day	about 170 kcal/day	+330 kcal/day
7–12 months (with solid foods)	about 400 kcal/day	none counted	+400 kcal/day

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).

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. It never goes below 1,800 kcal a day.

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 ≈ 2,260 kcal/day · weight loss: 1,800 (minimum)
More active	Same, but exercising 3–5 days a week	Without breastfeeding ≈ 2,170 · total ≈ 2,500 kcal/day · weight loss ≈ 2,000
Older baby, partly breastfed	Same as the first example, baby 7–12 months, about half breast milk	Extra ≈ +200 · total ≈ 2,130 kcal/day

How to read your result

• It’s an estimate. Formulas can be off by 10% or more 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, usually around 6 to 8 weeks after birth, 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.