Baby’s Milk Intake Calculator (breast milk per day and per bottle)

Understanding the baby's milk intake calculator — concept and principle

This calculator estimates how much breast milk an exclusively breastfed baby takes on average per day and per feed, from the baby's weight and age group. It also shows the rate used, the average daily total at that age and the high end of the normal range. Parents giving expressed milk in a bottle, and those returning to work, use it to plan amounts.

Weight × age-based rate — with the default inputs: 86 mL per feed.

How it is calculated

Daily intake = weight (kg) × average intake per kg for the age group
Rates (US EPA, 2011): birth–1 month 150; 1–3 months 140; 3–6 months 110; 6–12 months 83 mL/kg a day (with solids from about 6 months)
Per feed = daily intake ÷ feeds per day
Average daily totals by age: 510, 690, 770 and 620 mL; mean + 2 SD about 950–1,000 mL

The principle

The US Environmental Protection Agency's Exposure Factors Handbook pooled studies that weighed exclusively breastfed babies before and after feeds. Expressing intake per kilogram makes the figures usable for babies of different sizes. Breast-milk intake rises quickly in the first month and then stays fairly stable while the baby grows, so the rate per kilogram falls with age. In a study by Kent and colleagues (2006), healthy 1–6-month-old babies took roughly 460 to 1,320 mL a day over 6 to 18 feeds, so individual babies vary a lot.

Worked example

Defaults: 5.5 kg, 1–3 months, 9 feeds a day.

Rate used = 140 mL per kg a day.
Daily intake = 5.5 × 140 = 770 mL.
Per feed = 770 ÷ 9 = 86 mL = 2.9 fl oz.
Average at this age = 690 mL a day; high end = 980 mL.

How to read the result

Use the per-feed figure as a starting amount for bottles of expressed milk, then adjust to your baby's hunger and fullness cues. Signs that a baby is getting enough include steady weight gain, plenty of wet nappies and contentment after feeds. Bottle-fed babies sometimes take more than they would at the breast, so paced feeding can help.

Common mistakes

Using formula guidelines for breast milk.
Expecting the same amount at every feed; feeds vary through the day.
Comparing a single pumping session with a baby's intake.
Using the figure for a sick or premature baby without professional advice.

Keep in mind: Not medical advice. If you are concerned about your baby's feeding or weight gain, ask your midwife, health visitor, lactation consultant or doctor.

Frequently asked questions

How much breast milk does a 2-month-old need?

On average about 140 mL per kg a day; for 5.5 kg about 770 mL, spread over the day's feeds.

How often do breastfed babies feed?

Typically 6–18 times a day, about 11 on average in one study.

Does milk intake increase after 1 month?

Only slightly; it stays fairly stable from about 1 to 6 months.

Sources: US EPA, Exposure Factors Handbook 2011 Edition, Chapter 15 "Human Milk Intake", Table 15-1 · Kent JC et al., "Volume and frequency of breastfeedings and fat content of breast milk throughout the day", Pediatrics 2006;117(3):e387–e395

Checked 9 Nov 2026. US EPA, Exposure Factors Handbook 2011 Edition, Chapter 15 “Human Milk Intake”, Table 15-1 (recommended mean and upper-percentile intake rates for exclusively breastfed infants); Kent JC et al., “Volume and frequency of breastfeedings and fat content of breast milk throughout the day”, Pediatrics 2006;117(3):e387–e395.

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