Breastfeeding Calorie Calculator
Work out how many calories you need while breastfeeding and how much you can safely eat to lose weight without cutting milk supply. Built on the Mifflin-St Jeor equation plus the net energy cost of milk production, with the 1,800 calorie floor used in lactation guidance.
Quick answer
Maintenance is about 2,502 kcal/day, and a safe target is 2,002 kcal/day — about 125 g protein, 67 g fat and 225 g carbohydrate.
Milk production costs roughly 500 kcal/day in total, but only about 330 kcal/day has to come from food — the rest comes from fat stored during pregnancy, and you need about 32 oz of extra fluid per day.
Your details
Daily calorie target
2,002 kcal
Maintenance 2,502 kcal · deficit 500 kcal/day (~1 lb/week)
How your number is built
- Resting energy (Mifflin-St Jeor)
- 1,401 kcal
- Activity factor
- × 1.55
- Maintenance before milk
- 2,172 kcal
- Extra intake for milk
- + 330 kcal
- Maintenance while breastfeeding
- 2,502 kcal
Protein
125 g
Fat
67 g
Carbs
225 g
Macro split: 25% of calories from protein, 30% from fat, 45% from carbohydrate — a distribution that keeps protein high enough for milk production while you lose weight.
Not medical advice
This is a population estimate, not a prescription. Milk supply, postpartum recovery, medication and medical conditions all change what is right for you — confirm any calorie target with your OB, midwife or a registered dietitian, and raise intake if your supply drops. A sudden large cut can reduce supply even when the total stays above the floor, so taper rather than dropping all at once.
How this calculator works, and why the numbers differ between sites
- Resting energy uses the Mifflin-St Jeor equation for women: 10 × kg + 6.25 × cm − 5 × age − 161.
- That value is multiplied by an activity factor from 1.2 (sedentary) to 1.9 (very active).
- Producing milk costs about 500 kcal/day in total, but roughly 170 kcal/day of that comes from fat stored in pregnancy, so the extra food needed is about 330 kcal/day in the first six months and about 400 kcal/day from 7-12 months, when that credit no longer applies. That is why the CDC recommends 330-400 extra calories while other sources quote 500 — one is net intake, the other is gross milk production. Partial breastfeeding is pro-rated by the share of feeds that are breast milk.
- Your goal deficit (0, 300 or 500 kcal/day) is subtracted, then the result is raised to the 1,800 kcal/day floor whenever you are still producing milk. Below about 1,500 kcal/day milk volume can fall by roughly 15%, so that floor is a warning line rather than a target.
- Weight change is projected with the 3,500 kcal per pound approximation, and 250-500 kcal/day — about 1 lb per week — is the range most guidance treats as safe while nursing.
Your inputs: 30 years old, 68 kg, 5′5″, moderately active (moderate exercise 3-5 days/week), breastfeeding at the breast, 100% of feeds breast milk, 1 baby.
Sources for the constants used here: CDC maternal diet guidance (330-400 extra kcal/day), HHS/ODPHP MyHealthfinder, the Academy of Nutrition and Dietetics on weight loss while breastfeeding (1,800 kcal/day floor and 1 lb/week), and the Mifflin-St Jeor equation with its standard activity multipliers.
About This Calculator
Estimate how many calories you need while breastfeeding and how much you can safely eat to lose weight without cutting milk supply. Uses the Mifflin-St Jeor equation plus the energy cost of milk production, an 1,800 calorie floor while nursing, and a protein/target macro split.
Frequently Asked Questions
How many calories should a breastfeeding mom eat to lose weight?
Start from maintenance — your resting energy plus activity plus the extra energy milk production needs from food — then subtract a modest deficit of 300-500 calories a day.
The extra food energy is about 330 calories a day for exclusive breastfeeding in the first six months, rising to about 400 calories a day from 7-12 months once solids start. Aim to lose about one pound per week and never take the total below 1,800 calories while you are producing milk. A worked example: 30 years old, 165 cm, 68 kg, moderately active, exclusively breastfeeding gives maintenance of about 2,500 calories and a target of about 2,000 calories for one pound a week.
How many extra calories does breastfeeding burn?
Milk production costs roughly 500 calories a day in total, but you do not need to eat all of it: about 170 calories a day come from fat stored during pregnancy. The extra intake is therefore about 330 calories a day for exclusive breastfeeding at 0-6 months, which is exactly the 330-400 calories the CDC recommends for well-nourished breastfeeding mothers.
This is why sources disagree: 500 is the gross cost of making milk, while 330-400 is the net amount you need to eat. From 7-12 months the pregnancy fat credit is gone, so the extra intake is about 400 calories a day. Partial breastfeeding is pro-rated — at half breast milk and half formula, count about 165 calories a day.
Can I diet while breastfeeding without losing my milk supply?
A gradual deficit is considered safe: about one pound per week, which is a 300-500 calorie daily deficit, with a floor of 1,800 calories a day. A randomised trial of overweight exclusively breastfeeding mothers (Lovelady et al., New England Journal of Medicine, 2000) used a 500 calorie deficit with a minimum 1,800 calorie intake and found no effect on infant weight gain or length.
What does affect supply is going too low or cutting suddenly. Below roughly 1,500 calories a day milk volume can fall by about 15%, and a sudden large drop can reduce supply even if the weekly total stays above the floor — taper gradually. Watch diaper counts and weight gain rather than the scale alone.
Why does this calculator refuse to go below 1,800 calories?
The 1,800 calorie floor comes from the Academy of Nutrition and Dietetics guidance on losing weight while breastfeeding: eating less than 1,800 calories per day may reduce how much milk your body makes. It is not an ACOG figure — ACOG publishes no numeric calorie floor.
When your inputs would put the target below 1,800, the calculator holds it at 1,800 and shows the slower projected rate of loss instead of printing an unsafe number. If your estimated maintenance is itself below 1,800 calories a day, no deficit is applied at all. If your BMI is under 18.5, no deficit is applied either.
How much protein do I need while breastfeeding?
This calculator puts 25% of your calories into protein, which at a 2,000 calorie target is about 125 grams a day — roughly 1.8 grams per kilogram of body weight. That is comfortably above the 71 grams a day RDA for lactating women and is enough to support milk protein production while you lose fat rather than muscle.
The remaining calories are split 30% fat and 45% carbohydrate, a distribution close to the one used in the postpartum weight-loss trials. Spread protein across meals and snacks rather than trying to hit the number in one sitting.
How fast can I safely lose weight after giving birth?
About one pound (0.45 kg) per week, or no more than four pounds a month. Research on moderate weight loss during lactation (Dewey, Journal of Nutrition, 1998) found that losing no more than about 2 kg — 4.4 lb — per month does not adversely affect milk production in women who were not underweight to begin with.
Most guidance is also to wait until about two months postpartum before running any deficit, because that is when milk supply is still being established. This calculator applies no deficit when you tell it you are less than two months postpartum.
Does exclusive pumping burn the same calories as nursing?
Yes, essentially the same. The energy cost is driven by how much milk you produce, not by whether the milk leaves your breast or a bottle, so exclusive pumping costs about the same 330 calories a day as exclusive nursing in the first six months.
If your daily pump output is lower than a baby would take, your real cost is proportionally lower too — use the share-of-feeds selector to pro-rate it rather than assuming a full 330 calories.
How many extra calories do I need for twins?
As an estimate, double the single-baby figure: about 660 extra calories a day for exclusively breastfeeding twins. There is no authoritative measured calorie value for multiples, so treat this as an estimate rather than a guideline.
What matters more than the number is not dieting hard while feeding two babies. Keep intake at or above the 1,800 calorie floor, and if you are feeding triplets or more, ask a dietitian for a personal target instead of scaling a rule of thumb.
The SuperCalc Editorial Team maintains calculator interfaces, formula notes, examples, and supporting explanations. Methods, assumptions, source links, and review depth vary by calculator and are documented on the relevant page where available.