Flange Fit Guide: Why One Size Doesn’t Fit All

Let’s talk about flange fit!

When it comes to pumping, one of the most common challenges parents face is flange sizing. Many pumps come with a “standard” size, but the truth is: there’s no such thing as a one-size-fits-all flange.

A flange is the part of a pump that the breast/nipple goes into. They can sometimes be called different names such as breast shield, horn, tunnel, or funnel. They often come as a size 24mm as the standard diameter, but flanges aren’t “one size fits all”. If you think about how everyone has different shoe sizes, then it makes sense that everyone would have different nipple sizes too. If you are wearing the wrong shoe size, it can be uncomfortable and not feel right. Same thing applies to your pump flange size.

Why Flange Fit Matters

A flange that’s too large can pull in excess areola, causing pain, swelling, and poor milk removal. Too small, and the nipple may rub or become pinched. Both scenarios can reduce milk output and make pumping uncomfortable.

The right flange size:

• Supports comfortable pumping sessions
• Helps protect nipple health

• Improves milk flow and efficiency

Measuring at Home: A Helpful Starting Point

One way to get a sense of your flange size is by measuring the tip of your nipple (not including the areola).

Here’s how you can try it at home:

1. Use a ruler or measuring tool marked in millimetres.

2. Measure the diameter of your nipple at the tip, when it is not swollen or engorged.

3. Use this as a starting point for choosing flange size.

Important note: Measuring is just a guideline.

• Nipples shouldn't swell during pumping
• Comfort matters more than numbers. A technically “correct” size that hurts isn’t the right fit.
• Sometimes parents need one size on each breast, or find their size changes over time.

This is why trial, adjustment, and support make such a difference — measuring gives you a starting place, but not always the full answer.

Finding Your Best Fit

It’s normal to try a couple of sizes before finding what works best. Comfort, not just “fit,” is the biggest factor.

If you’re unsure where to start, a lactation consultant can help guide you through sizing and pump setup. At Flow & Flourish, we offer personalised pumping consults to take the guesswork out of flange fitting and help you pump with confidence.

Supportive Tools and Products

To make pumping more effective and comfortable, we’ve carefully selected products that support the right flange fit:

• Breast pump parts and accessories – keep your pump working at its best
• Flange accessory kits – use your pump’s motor with our kits for a perfect fit
• Maymom flanges – available in a wide range of sizes and shapes to help you find your match

Each item is chosen with parents in mind, so you can focus on feeding, not fussing with gear.

You Don’t Have to Figure It Out Alone

If pumping feels uncomfortable or your output isn’t what you expect, don’t assume it’s “just how it is.” More often than not, it’s a flange fit issue that can be solved with the right support.

💡 Book a 1:1 pumping consult with Flow & Flourish to find your ideal flange size, optimise your pump, and learn practical tips that make a difference.

👉 Whether you’re new to pumping or looking to make it more comfortable, remember: one size doesn’t fit all — and you deserve to pump without pain.