Buying baby clothes should be exciting, but for many parents, it turns into a guessing game. Will newborn size fit? Should you size up? And what about preemies or fast-growing little ones? With so many different size charts across brands, it’s no surprise that parents feel overwhelmed.
At Vincent Faith Baby, we know that getting the perfect fit is about more than just looking cute—it’s about comfort, practicality, and making sure your little one feels safe and snug. That’s why we’ve created this guide to take the guesswork out of baby clothing sizes.
Why Sizing Right Matters
Babies grow fast—sometimes up to 1 inch per month in the first 6 months. That’s why picking the right size is important, not just for comfort but also for:
• Safety – Clothing that’s too loose can bunch up and be a suffocation risk, while clothes that are too tight can restrict movement.
• Medical Needs – Preemies and NICU babies need clothing that works around feeding tubes and monitors without interfering with care.
• Practicality – The right size means fewer outfit changes due to discomfort or improper fit.
How to Measure Your Baby for Clothes
Instead of relying on age-based sizing, measuring your baby ensures the best fit. Here’s what you need:
• A soft measuring tape (or a piece of string and a ruler if you don’t have one)
• A calm, fed baby—measuring is easiest when they’re content
• The three key measurements:
1. Weight – Most baby clothing brands base their sizes on weight rather than age. A 3-month-old could still fit newborn sizes if they’re on the smaller side, while a chunky baby might need 6-month sizing early.
2. Length (Height) – Measure from the top of the head to the bottom of the feet while baby is lying flat. If they’re between sizes, size up.
3. Chest & Waist – For a snug but comfy fit, measure the widest part of their chest and waist. This is especially important for onesies and sleepers.
Baby Clothing Size Chart: General Guidelines
Every brand is slightly different, but here’s a basic breakdown of baby clothing sizes:
Preemie: Up to 5 lbs / 17 inches
Newborn: 5–8 lbs / 17–21 inches
0-3 Months: 8–12 lbs / 21–24 inches
3-6 Months: 12–16 lbs / 24–26 inches
6-9 Months: 16–20 lbs / 26–28 inches
9-12 Months: 20–24 lbs / 28–30 inches
Vincent Faith Baby’s micro-preemie and preemie sizes are designed specifically for the tiniest newborns, ensuring a perfect fit that doesn’t overwhelm them.
Choosing the Best Fit for NICU and Preemie Babies
If your baby was born prematurely, traditional newborn sizing won’t work. Standard newborn clothing can be too big, making it difficult to dress your little one comfortably, especially if they have medical equipment attached.
Vincent Faith Baby’s NICU-friendly onesies are made for micro-preemies and preemies, with:
• Crossbody openings that allow easy dressing without disturbing feeding tubes
• Soft, organic cotton fabric that won’t irritate delicate skin
• Perfectly fitted mittens that help prevent babies from pulling out medical equipment
Many hospitals recommend bringing a few preemie-sized outfits to ensure a proper fit once your baby is ready to wear clothing.
Should You Size Up or Stick to the Current Size?
• For everyday wear – If your baby is between sizes, sizing up allows more room to grow.
• For NICU or preemie babies – Stick to fitted sizes to avoid clothing bunching or interfering with medical care.
• For sleepwear – Choose a snug fit to prevent loose fabric from riding up.
Why Organic Cotton is Best for Baby Clothes
Fabric choice matters as much as fit. Since baby skin is thinner and more sensitive than adult skin, organic cotton is the best option. Unlike synthetic fabrics, it:
• Is free from harsh chemicals and dyes that can irritate baby skin
• Is breathable to prevent overheating
• Feels softer against delicate skin
At Vincent Faith Baby, all of our preemie and NICU clothing is made with 100% GOTS-certified organic cotton for the gentlest touch.
Making Baby Clothing Sizing Easier
Shopping for baby clothes doesn’t have to be stressful. By measuring your baby, checking weight guidelines, and choosing brands that cater to delicate newborns, you can confidently pick outfits that fit well and keep your little one comfortable.
At Vincent Faith Baby, we create clothing with inclusive sizing for the smallest miracles—because every baby deserves a perfect fit from day one.