A breast milk calculator for bottles, storage and alcohol
This breast milk calculator answers the three questions pumping parents ask most. How much expressed milk should go in each bottle? How long can breast milk be kept at room temperature, in the fridge or in the freezer? And after a glass of wine, how long should I wait before breastfeeding? Pick a tab, fill in a few boxes and read the answer in mL or oz.
The amounts follow published guidance rather than a pump maker’s chart: an exclusively breastfed baby between one and six months takes about 750 mL (25 oz) a day, so you divide that by the number of feeds. Storage times come from the CDC and the NHS side by side, and the alcohol timing uses the CDC rule of about two hours per standard drink. It is general information for parents, not medical advice.
How to use the Breast Milk Calculator
- On Amount per bottle, choose your baby’s age and enter how many feeds they have in 24 hours.
- Enter Feeds you will miss to see how much milk to leave with a carer. A weight is optional.
- On Storage times, enter when the milk was expressed and where it is kept to get a use-by date and time from the CDC or NHS.
- On Alcohol timing, choose the drink, how many and when you started, to see the earliest time to breastfeed again.
- Switch between mL and oz, and kg and lb, at any time.
Breast Milk Calculator features
Per-bottle amount
Daily intake ÷ feeds, with the usual range and the total to leave for missed feeds.
First days to 12 months
Day-by-day amounts for days 1–3, the first-week limit, then the 1–6 month plateau.
Use-by calculator
CDC and NHS times for room, fridge, ice compartment, freezer, cool bag, thawed and leftover milk.
Alcohol wait time
Grams of alcohol for common drinks in US, UK and Indian measures, converted to standard drinks.
mL or oz
US fluid ounces; your unit choices are remembered on this device.
How much expressed breast milk per feed?
Sources: HSE (Ireland) “How much breast milk to express” (reviewed February 2026) and KellyMom’s summary of intake studies (updated August 2026). Worked example: a 3-month-old who feeds 8 times a day needs about 750 ÷ 8 = 94 mL, so about 95 mL (3.2 oz) per bottle; for three missed feeds, leave about 285 mL. Unlike formula, breast milk intake hardly changes with weight between one and six months, so weight-based charts tend to overestimate. After six months, milk stays important but the amount falls gradually as solid food increases.
| Age | Per feed | In 24 hours |
|---|---|---|
| Day 1 | a few drops to 5 mL | — |
| Day 2 | 5–15 mL | — |
| Day 3 | 15–30 mL | — |
| First week | no more than about 60 mL | about 475 mL (16 oz) at day 5 |
| After 4–5 weeks | about 90–120 mL (3–4 oz) | 700–900 mL |
| 1–6 months | 750 mL ÷ number of feeds | about 750 mL (25 oz); usually 570–900 mL |
Storing breast milk safely
- Label each container with the date and time, and use the oldest milk first.
- Store small portions (60–120 mL) so less is wasted; leave room at the top for milk to expand when frozen.
- Thaw in the fridge overnight or in a bowl of warm water — never in a microwave, which heats unevenly.
- Never refreeze milk that has thawed. Swirl, rather than shake, milk that has separated.
- The CDC and NHS differ on fridge time (4 days vs up to 8 days at 4 °C or colder): if your fridge temperature is unknown, use the shorter time.
Alcohol and breastfeeding
Alcohol passes into breast milk at about the same level as in your blood and peaks 30–60 minutes after a drink. The CDC says not drinking is safest, that up to one standard drink a day is not known to harm a baby, and that waiting about two hours per drink before breastfeeding reduces the baby’s exposure. A standard drink is 14 g of alcohol — so a 175 mL glass of 12% wine (16.6 g) counts as about 1.2 drinks and a UK pint of 4% beer as about 1.3.
Expressing and throwing milk away (“pump and dump”) does not speed up clearance; it only keeps you comfortable and protects supply. For bottle amounts of formula, see the baby feeding chart; to check feeds are going in, count nappies with the diaper calculator.
Breast Milk Calculator FAQ
How much breast milk per feed should I give in a bottle?
From one to six months, about 750 mL (25 oz) a day divided by the number of feeds: about 95 mL (3 oz) for 8 feeds, or 125 mL for 6 feeds. Start a little lower and add more if your baby is still hungry.
Does the breast milk calculator use mL per kg?
You can enter a weight, but only as a comparison. Formula guides use about 150 mL per kg a day; breastfed babies’ intake stays about the same from one to six months whatever their weight.
How long can breast milk sit out?
Up to 4 hours at room temperature (25 °C / 77 °F or colder) according to the CDC. Once a feed has started, use leftovers within 2 hours (CDC) or 1 hour (NHS).
How long does breast milk last in the fridge and freezer?
CDC: up to 4 days in the fridge, about 6 months in the freezer (up to 12 months acceptable). NHS: up to 8 days at 4 °C or colder, 2 weeks in the ice compartment and 6 months in a −18 °C freezer.
How long after drinking alcohol can I breastfeed?
The CDC suggests waiting about 2 hours per standard drink. The alcohol tab works out the time for common drinks.
Is this medical advice?
No. It is general information from published guidance, as of October 2026. Your midwife, health visitor, doctor or lactation consultant can advise on your own baby.