Why Bottle Size Isn't Just About Volume

September 6, 2026

Bottle size isn't only about how much milk it holds. It also reflects how the bottle is meant to be held and used at that stage. A bigger bottle isn't automatically better if your baby isn't at the stage where that size actually makes sense yet.

150ml: The Caregiver-Fed Stage

The smaller 150ml size is built for the early stage, when a parent or caregiver is holding and giving the bottle during most feeds. It's lighter and easier to manage for whoever is doing the feeding, especially during longer feeding sessions.

This size also naturally matches the smaller feed volumes typical of the early months, so you're not left with a bottle that always looks half empty.

250ml: The Bigger Appetite, More Independent Stage

As your baby grows and starts drinking more per feed, the 250ml size becomes the better fit. It's not just a bigger container though. This size is shaped with an ergonomic design meant to be held by your baby themselves, supporting the stage where they're starting to want more independence during feeding time.

How to Know When to Size Up

Rather than going by a fixed age, it helps to watch for a few signs:

Your baby finishes a 150ml bottle quickly and still seems hungry
Feeds are becoming noticeably larger and more frequent
Your baby is starting to reach for and hold the bottle themselves

If you're noticing these, it's usually a good sign that the 250ml size will serve your baby better going forward.

The Common Mistake: Buying Big Too Early

It's easy to think a bigger bottle means less shopping later, but sizing up too early doesn't actually help. If your baby isn't ready to hold a bigger bottle, or isn't drinking that much yet, the extra size just becomes awkward rather than useful. Starting with the 150ml size and moving up later is a completely normal path, not something to rush.

Two Sizes, Two Stages

Mubsie's bottles come in both 150ml and 250ml sizes, each designed around a specific stage rather than just being a smaller or larger version of the same bottle. The 150ml is built for easy caregiver holding during early feeds, while the 250ml's ergonomic shape supports your baby as they grow toward feeding more independently.

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