What this calculator does
Producing milk costs energy, and the standard allowance is an extra 330 kcal a day for the first six months and 400 after that. That increment sits on top of whatever the baseline requirement already is.
The baseline does most of the work. A 30 year old at 65 kg and 165 cm with light activity has a baseline of 1,884 kcal, and the lactation increment brings the total to 2,214.
The formula
Basal metabolic rate is calculated with the Mifflin-St Jeor equation and multiplied by an activity factor to give the baseline requirement. The lactation increment for the chosen stage is then added.
| Term | Meaning |
|---|---|
| Lactation increment | The extra energy for milk production: 330 kcal in the first six months, 400 after. |
| TDEE | Total daily energy expenditure, being the baseline before the increment. |
| Mifflin-St Jeor | The equation used for the basal rate. |
The inputs explained
| Field | What to enter |
|---|---|
| Age (years) | Age in years. |
| Weight (kg) | Body weight in kilograms. |
| Height (cm) | Height in centimetres. |
| Activity level | Activity level, which multiplies the basal rate. |
| Breastfeeding stage | Breastfeeding stage, which selects the increment. |
When to use it
Planning nutrition while breastfeeding
The requirement is meaningfully higher than before pregnancy.
Understanding increased hunger
An extra 330 kcal a day is a real physiological demand.
Discussing intake with a professional
A baseline figure makes the conversation more concrete.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does activity level change the total?
The same person at four activity levels.
| Activity level | Daily calorie needs while breastfeeding | Baseline TDEE (no lactation) |
|---|---|---|
| Sedentary | 1,974 kcal/day | 1,644 kcal/day |
| Light | 2,214 kcal/day | 1,884 kcal/day |
| Moderate | 2,454 kcal/day | 2,124 kcal/day |
| Very active | 2,694 kcal/day | 2,364 kcal/day |
Questions
Where do 330 and 400 come from?
They are the standard dietary reference intake increments for lactation, based on the energy content of milk produced and adjusted for the energy mobilised from stores laid down in pregnancy. The second figure is higher because that mobilisation has largely finished.
Should I eat to this figure exactly?
No. It is a population estimate, and actual needs vary with milk supply, body composition and activity. Appetite is usually a reasonable guide, and a dietitian or health professional can advise on anything more specific.
Does restricting calories affect milk supply?
It can, particularly with sharp restriction. Gradual change is generally advised while breastfeeding, and anyone planning to lose weight during this period should discuss it with their healthcare provider first.
Does this apply to partial breastfeeding?
Not directly. The increment assumes exclusive breastfeeding. Mixed feeding produces less milk and therefore needs less additional energy, roughly in proportion.
For the baseline calculation on its own, see the TDEE calculator. For infant formula volumes, see the baby formula intake calculator.