Breast storage capacity

Breasts come in a variety of different shapes and sizes (isn’t that nice?). But what you may not know is that the inside of our breasts vary just as much as the outside. We have differing amounts of fatty tissue and milk-secreting glands, our ducts and glands may be larger or smaller and we don’t all have the same number of pores opening on the nipple. But the most interesting and relevant difference is in out breast storage capacity.

Breast storage capacity title

What is breast storage capacity?

Breast storage capacity is literally what the name says: the amount of milk that your breasts are physically capable of holding. Some women’s breasts can store a lot of milk and others only a smaller volume. The interesting thing is that you can’t tell just by looking – large breasts don’t necessarily store more milk than small ones. Your breast storage capacity is determined by how many glands and ducts there are in the breast and how large they are; and larger breasts typically contain more fatty tissue rather than more glandular tissue.Breast storage capacity anatomy


Why does breast storage capacity matter?

While your breast storage capacity affects how much milk you can have available at one time, it doesn’t affect how much milk you are able to produce. Studies have consistently shown that women with any size of breasts can produce enough milk on a daily basis, as long as the breasts are emptied often enough to stimulate continuing milk production.

Because the breast storage capacity influences how much milk is available at one time, it has certain predictable effects on baby’s feeding patterns:

If the breast has a small storage capacity… If the breast has a large storage capacity…
·         There is less milk available per feed, so

·         Baby will need to feed more times per 24 hours to get enough milk and

·         Baby will probably continue to need night feeds until he is much older

·         Baby will usually want both breasts at every feed

·         And, unfortunately, the breasts fill up more quickly, so you will be more prone to blocked ducts, engorgement and the like if baby misses a feed(sorry!)

·         There is more milk available per feed, so

·         Baby may need to feed fewer times per 24 hours to get enough milk and

·         Baby may start to drop night feeds sooner (although this is by no means guaranteed…)

·         Baby will usually be satisfied with only one breast per feed

·         Because it takes longer for the breasts to become full, you will be able to go longer between feeds without risking blocked ducts, engorgement and the like

I should add an important caveat though: this is just a typical behaviour, not a guarantee of how your baby will behave. Specifically, having a large storage capacity doesn’t guarantee that your baby will necessarily feed less frequently or sleep through the night at a younger age. Remember: breastfeeding is about a lot more than the milk, and babies enjoy frequent feeds for a variety of reasons. Let me use myself as an example: based on the amount I could pump in one session, I have an enormous storage capacity – and yet, both my boys continued with frequent feeds, day and night, well into their second or third years of life. They simply loved the breast for reasons that went beyond nutrition.

Breast storage capacity infographic

An illustration of how breast storage capacity works

Let’s look at a practical example. I’m oversimplifying things and making up some imaginary numbers here just to get the point across, but please bear with me:

Let’s say Mom S, with a small storage capacity, has 80 ml of milk available per feed. Mom L, with a large storage capacity, has 120 ml available per feed. Their babies both need around 960 ml of milk per day. So (assuming that their babies drink all the milk that’s available at each feed – just to keep things simple), ten seconds with a calculator will tell you that Baby S will need 12 feeds per day and Baby L only 8 feeds per day. If both moms are feeding on demand, they will likely see that Baby S simply asks for a feed more often than Baby L; and as long as Mom S responds to baby’s cues, all will be well and both babies will thrive.

But let’s say Mom S starts to worry – why is her baby drinking every two hours and while mom L’s baby only drinks every three hours? Thinking that she is spoiling her baby (because that’s what her mom-in-law thinks) or perhaps overfeeding him (because that’s what the nurse at the clinic said), she starts using all kinds of techniques to stretch baby to three-hourly feeds. But can you see the problem? She still only has 80 ml of milk available at every feed! So now poor baby S only has access to 640 ml (80 ml x 8 feds) per day. Predictably, baby S doesn’t gain weight very well over this time, because he’s been underfed. And who gets the blame? The breast milk, of course: “I knew your milk wasn’t strong enough when that baby wanted to drink so often; now you see, it’s not even nutritious enough to let him grow normally!” And just like that, the breastfeeding journey breaks down.

I’m sure you’ve heard Mom S’s story, or one very like it, if you’ve had anything to do with moms and babies in your life. It just makes you want to cry. If poor Mom S (or her healthcare team!) had only understood that breasts differ in their storage capacity, and the best thing she could do was to keep following her baby’s lead, the whole mess would have been avoided.

And now the million-dollar question:

How do I know whether I have a small or large storage capacity? In all honesty, it doesn’t matter. The only reason why it helps to be aware of this is so that you will remember not to compare yourself and your baby to anyone else. Just because your friend’s baby feeds every 4 hours and sleeps though the night doesn’t mean that it’s normal or better, or that your baby should be doing the same thing. In fact, if a woman with a small storage capacity were to attempt a 4-hourly schedule, she would have three predictable outcomes: poor weight gain in baby, blocked ducts and engorgement (perhaps even mastitis), and a reduction in her milk supply. So it just provides another illustration of why it’s best to follow your own baby and your own body’s lead with breastfeeding, and not try to fit some arbitrary pattern.

On a related note, a discussion of breast storage capacities makes a very good, scientifically valid answer for all the doubters and nay-sayers who want to convince you that you need to “stretch baby’s feeds”.

In conclusion

Big ones, small ones, thin and fat and tall ones… Remember, the insides of your breasts are as unique as every other part of you. So follow the feeding patterns that your breasts and your baby need, because trying to squeeze into any other pattern may just spell disaster for you.

I’m curious – who out there can relate to this illustration? Do you have a “typical” large or small storage capacity, or do you have something mixed up like I do? Tell me in the comments section!


  1. Krysta Wolfangel

    I have donated around 90 gallons of breastmilk to babies. I believe women are misinformed about how much breastmilk they make and store. I think women with small storage capacity often think and are told that they do not produce enough milk and therefore stop breastfeeding and or supplement. It is such a shame because at this point the women lose supply and then theor milk dries up. I here this story over and over again

  2. Taylar

    Sometimes my right breast gets engorged, mostly in the early morning, hardly ever in the evening. It seems that my son (almost 2 months) likes to graze eat all afternoon but he fully eats at night before bed and in the morning. I’m not sure why my right breast keeps getting engorged.

    1. Sanja (Post author)

      Might be that your right breast produces more than your left. It’s pretty common for that to happen. Best thing I can think of is to let baby drink the right one dry before bed, and then give it first when he wakes up again. If you have one breast that produces noticeably more milk, it’s fine to feed on that one more often than the other one.

  3. Sophie

    I probably have a small capacity. Both my kids feed frequently and I can’t pump more than 40-50ml per session whether they’re an hour apart or five hours apart. It’s frustrating as I have a very fussy eater who doesn’t settle at the breast and I try and pump for him to feed with a bottle but I can’t pump fast enough to keep up with him.

  4. Cassandra

    Thanks for this post. I think I have a small capacity which I had always assumed was just low supply. I was able to pump around 60-80 mls in about 15 mins, and 90 mls at most in 20 mins. After 1-2 hours I’d get the same amount. I’ve had clogged ducts so many times now as well. I ended up supplementing with formula because I thought I should have been able to feed every 3 hours. It sucks that none of my healthcare providers, midwives, or even lactation consultants were able to give me this information- they all just told me it was low supply. Guess I shall try again with my next baby!

    1. Sanja (Post author)

      Yep, that sounds like a small capacity. Shame no one told you that it’s okay to feed more often if that’s what your baby needs. The blocked ducts should have clued them in that it’s not a supply issue. At least now you know better for next time. And – good news – your capacity tends to increase with each baby 🙂

  5. Chelsea

    Thank you for this post! I am home on maternity leave after delivering twins and am trying to exclusively breast feed. When speaking about capacity and pumped amounts, is the amount discussed per breast or total amount?

    1. Sanja (Post author)

      In this particular article, the amounts are totally made up just to illustrate the concept, so please don’t use them to compare yourself to!

  6. Penny

    Your blog is so helpful thank you but I am really stuck in how to get this breastfeeding thing to work for me, I think I have extremely low capacity and low supply since my breasts never feel engorged. I have been feeding my baby every three hours but after slow weight gain and then weight loss have had to supplement my seven week old boy after each breastfeed. My goal is to avoid all supplementing and pumping. I only pump 25-30 mls after feeding, and get 50-60 mls if I miss a three hourly feed, so it looks like I would need to breastfeed him every hour or two? He already spends a whole hour on the breast before the bottle, so that seems impossible! Should he be feeding for less time? He has an arched palate which probably complicates things. I can’t help but feel doomed about it all which I’m sure doesn’t help either.

    1. Sanja (Post author)

      Wow Penny, sounds like you’re really struggling. It’s difficult to give an assessment without seeing your baby feed. From the long feeds, it sounds to me like he is not suckling effectively, so not removing much milk. This has probably impacted your supply. My best advice to you would be to see a lactation consultant to assess what exactly the sucking problem is and come up with a plan to address it; and also to rule out other reasons for low supply on your side.

  7. Eva

    Does the storage capacity change from pregnancy to pregnancy?
    With my first I definitely know that I had a small storage because my son was feeding every two hours for the first 6 months and needed two night feedings until he was 10 months old.
    I’m worried that with the second baby this will also be the case. Just curious if perhaps the storage amounts might increase.

    1. Sanja (Post author)

      I don’t know about storage capacity specifically, but milk production definitely tends to increase with each pregnancy, so I think there’s a fair chance that things may go better the next time around. That said, needing 2 night feedings at 10 months is not at all unusual – I dare say it’s the norm for breast fed babies.


    Do you have any scientific article about this subject?

    1. Sanja (Post author)

      Unfortunately not, although it’s mentioned in most of the big lactation textbooks. I can’t even imagine how you would study it properly. But it’s a useful concept to explain what we observe in practice.


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