Spill-Proof Milk Bags
Spill-Proof Milk Bags
Spill-Proof Milk Bags
Spill-Proof Milk Bags
Spill-Proof Milk Bags

Spill-Proof Milk Bags

All-In-One Milk Collection and Storage (48-Pack)

Meet the only disposable, spill-proof collection and storage Milk Bag. Our patented, no-spill technology lets you pump directly into self-sealing storage bags.

  • Essential to pumping with Willow (24 bags included in Pump Kit)
  • Offer truly spill-proof mobility - pump in any position (even lying down or doing yoga)
  • Pump on the go and toss into your purse or cooler bag - totally hygienic, no need to seal or transfer
  • Unique one-way valve so milk goes in and doesn’t come out
  • Pump and store milk in the same collection and storage bag
  • Fridge and freezer safe
  • Holds up to 4 oz.
  • BPA free
  • Recyclable


Free Shipping on Orders Over $70
Free Shipping on Orders Over $70

Find Your Flange Size

with a ruler app on your phone

    Your flange size is based on your nipple measurement in millimeters. Use an app ruler for easy and accurate sizing

    • Download "Ruler 2.0" for iOS or "Millimeter" for Android phones.
    • In iOS app settings, set measurement to “mm”. For Android, select default calibration.
    • Stimulate nipple to perk it up
    • Place phone screen perpendicular to nipple. (Figure 1)
    • Nipple base should line up with the zero points in the corner of app screen (Figure 2)
    • Slide measurement bar on screen to opposite nipple base - that’s your nipple measurement. (Figure 3)
    • Use a flange that’s 2-4 mm larger than your nipple measurement. (Figure 4)
      • Willow Size Guide

        Hold phone
        perpendicular to nipple.

        Willow Size Guide

        Use your finger to slide the ruler line to measure nipple.

        Flange Size Chart 4

        Find the right flange sized based on
        your measurements.

        Flange Size Chart