Breast milk stash calculator

Find out how much breast milk to freeze before you go back to work or stop pumping, and how much to store each day to get there.

How the calculator works

Going back to work. Your stash goal is the number of bottles your baby takes while you're away, times the amount in each bottle, times the days of backup you want. Most parents who pump at work use today's milk for tomorrow's bottles, so the freezer stash is a buffer for a missed session or a day you pump less, not every bottle you'll ever need.

Stopping pumping. Your stash goal is how much breast milk your baby drinks a day, times the number of days you want it to last. If your baby also has formula, enter only the breast milk part.

In both cases, the calculator takes away what's already in your freezer and spreads the rest over the days you have left.

How much breast milk does a baby drink?

Babies between 1 and 6 months old who only have breast milk drink about 25 oz (750 mL) a day on average, usually somewhere between 19 and 30 oz (570 to 900 mL). That amount stays fairly steady until solid foods start around 6 months.

To estimate a single bottle, divide the daily amount by how many times your baby usually feeds in 24 hours. A baby who feeds 8 times a day takes about 3 oz per bottle.

Every baby is different, so if you can, watch what yours actually drinks from a bottle for a few days and use that instead.

You don't need a huge stash

Photos of freezers packed with milk can make it seem like you need hundreds of ounces. Most parents going back to work need a few days' worth. If building a stash is adding stress, talk to your lactation consultant about a goal that works for you.

Freezing and storing your stash

These tips come from the CDC:

• Freeze small portions. Store 2 to 4 oz, or the amount your baby takes at one feeding, so less milk goes to waste.
• Label each bag with the date you pumped it.
• Leave about an inch of space at the top of the container, because milk expands as it freezes.
• Use the oldest milk first.
• Know how long it lasts. Frozen milk is best used within about 6 months, and is acceptable up to 12 months. Fresh milk keeps up to 4 days in the fridge.
• Don't refreeze thawed milk. Use milk thawed in the fridge within 24 hours.

Track your stash in Milk Diary

The calculator gets you a goal. Milk Diary helps you reach it:

• Set a daily storage goal using the amount from the calculator, and see how you're working toward building your stash each day.
• Set a daily pumping goal and watch it fill up with every session.
• Track fridge and freezer milk with automatic expiration dates.
• See how long your stash will last. The Freezer Timeline estimates how many days of milk you have.
• Spot trends week to week with daily totals and weekly insights.

Your data stays on your device and in your own iCloud. There's no account to create.

Sources

• Centers for Disease Control and Prevention. Breast Milk Storage and Preparation. Reviewed March 2026.
• Kelly Bonyata, IBCLC. How much expressed milk will my baby need? KellyMom.