Alppi Baby Diaper Size Calculator

A Better Fit Starts Here

Diaper Size Calculator and Baby Diaper Size Guide

Find a helpful starting size using your baby's current weight. Then check the fit around the waist and legs, because every baby is built differently.

7 Alppi sizesWeight-first guidanceInstant results
Quick TIP

Choose diaper size mainly by weight, not age. A good fit feels snug without deep marks, gaps, leaks, or blowouts.

Simple Two-Step Check

Find Your Baby's Diaper Size

Enter a recent weight for the best starting recommendation. Age is optional and only helps add context.

1. Enter Your Baby's Current Weight
Use a recent weight when possible.
Unit
2. Add Fit Details Optional

Are you seeing any of these signs?

♡

Your Fit Guide Will Appear Here

Enter your baby's weight to see a starting size and useful fit checks.

Why Diaper Size Is Based on Weight

Babies of the same age can have very different builds. Weight gives a better starting point because diapers must fit the waist, hips, and legs. Age can help with context, but it should not replace a fit check.

Parent tip:

Use a recent weight. Weigh yourself alone, then while holding your baby. Subtract the first number from the second.

All Seven Sizes

Alppi Diaper Size Chart by Weight and Age

Weight ranges can overlap. This gives growing babies more room to find a comfortable fit.

Size Weight Range Typical Age
Newborn 6-10 lb 2.7-4.5 kg 0-1 month
Size 1 8-17 lb 3.6-7.7 kg 0-4 months
Size 2 13-22 lb 5.9-10 kg 2-6 months
Size 3 Longest stage 19-30 lb 8.6-13.6 kg 6-18 months
Size 4 26-37 lb 11.7-16.8 kg 12-36 months
Size 5 33 lb and up 15 kg+ 24-36+ months
Size 6 35 lb and up 15.9 kg+ Potty-training age
Size 7 Extended 35-41 lb 15.9-18.6 kg Large or older toddlers

Typical ages are estimates. Your baby's current weight, shape, and fit matter more.

Check the Fit

Signs It May Be Time to Size Up

Your baby may need a larger diaper even while still inside the listed weight range.

  • Leaks or blowouts happen more often.
  • Deep marks remain on the waist or thighs.
  • The tabs stretch or barely reach the fastening area.
  • The diaper looks low or does not fully cover the bottom.
  • Your baby seems uncomfortable after fastening.

Stay With the Current Size When

  • The waist feels comfortable.
  • Leg cuffs sit flat without gaps.
  • There are no deep red marks.
  • Leaks and blowouts are uncommon.

If your baby is between sizes, try a small pack before buying a full box.

Four Easy Steps

How to Put on an Alppi Diaper

The right size can still leak when the leg guards or tabs are not positioned correctly.

  1. 1

    Open the Tabs

    Separate the soft hook tabs if they are stuck together.

  2. 2

    Fasten Evenly

    Secure both tabs at the marked area without overlapping them.

  3. 3

    Release the Guards

    Pull the leg leak guards outward to help prevent leaks.

  4. 4

    Check the Waist

    Leave enough room for two fingers at the back of the diaper.

Helpful Answers

Diaper Size Calculator FAQs

How do I know what diaper size my baby needs?

Match a recent weight to the range on the size chart. Then check the waist and thighs. A good fit is snug and gap-free without deep marks.

Should I size up or down when my baby is between sizes?

Stay with the smaller size when it fits comfortably and does not leak. Try the larger size when tabs are tight, marks appear, or leaks increase. Some parents prefer the roomier option overnight.

What size diaper does a newborn wear?

Alppi Newborn fits 6-10 lb, or 2.7-4.5 kg. Size 1 begins at 8 lb, so there is some overlap as babies grow. Check the actual fit instead of relying only on age.

What are the clearest signs that my baby needs a bigger size?

Watch for deep red marks, tabs that barely reach, repeated leaks, or poor bottom coverage. These signs can matter even when your baby is still within the package weight range.

How often do babies change diaper sizes?

There is no fixed schedule. Growth is often fastest during the first year, so check weight and fit regularly. Buy smaller quantities when your baby is near the top of a range.

Soft, Secure, and Ready for Every Stage

Find the Alppi Fit for Your Baby

Explore Wispy Cloud diapers in sizes designed for growing babies and toddlers.

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Your Journey, Simplified

Because at Alppi, our ultimate purpose is to simplify your parenting journey. We handle the details with care and safety, so you are free to focus on what matters most: cherishing every precious cuddle and celebrating each milestone with your little explorer.