Size Guides


My hope is that this Size Guide will help guide you to select the correct undergarment size for your child and take the guesswork out of it!

Main Points to Consider

  1. Sizing. Always size up from your baby’s current age (age 3 months? Get size 6 months.). If your 14 month toddler is large for his size (say, 75th percentile), you may want to get the 2T size. Check out the Size Charts, below, for more details on measurements and such.
  2. Measuring. See How to Measure, below, for details on how to measure your baby for the best fit.
  3. Size up. If in doubt, order the next size up. This is always the case with children’s clothing…if you aren’t sure, order the next size up so you’ll get many more months out of each size than if you order too snug. If your child runs tiny, you may not need to order a size up (my 5 year old can still wear Tiny Undies in 3T!). You know your child better than we do, so consider what you know when picking your sizes!
  4. Don't worry. If you order the wrong size, you can exchange them! We have a pretty easy exchange policy here. If you open your Tiny Undies and find they don’t fit quite right, you can return them so long as they’re not soiled, washed, or damaged by you, and if the packaging is in good shape. If the mistake was our fault, we pay for shipping back and forth. If the mistake or misguess was from your side, you pay for shipping back and forth. If it’s somewhere in the middle, we can split the difference.
  5. Shrinkage. We use preshrunk 100% cotton, but some shrinkage can be expected with repetitive washing. We recommend washing our products on cold and drying them on low, when possible.
  6. (Trainers) Fluffing. The absorbent core will “fluff up” after the first wash/dry. Just like any cloth diaper inserts or prefolds, Tiny Trainers will arrive somewhat flat and after a wash/dry or two, will fluff up so beautifully. This enhances the absorbency and also feels super cush to your babe.
  7. (TinyUps) Loose Fit. Keep in mind that our TinyUps cloth pull-up covers come in 3 simple sizes…they will be baggy so you can layer over our Trainers and Undies. Typically babies 0-6 mos wear size Small, 6-18 mos wear Medium, and 18 mos+ wear Large.

How to Measure

You’ll need either a flexible measuring tape (used for sewing) or a string and a ruler to measure your baby or toddler for our underwear to fit best. Here are some details on how to get your measurements for the above chart ranges. (Remember that the above ranges basically take your measurements and match them to our Undies, with the elastic in-mind. So, no further adjustments are needed once you’ve measured!)

Waist (below belly) – Do not measure your child at the belly button, but measure below the belly bulge at the top of the hips. Tiny Undies are anatomically-correct so the waistband sits right below the belly for a super-comfy fit. The elastic is not super-tight, but it is snug enough to not fall down. NOTE: Tiny Chaps also have velcro to further adjust the waist fit.

Low-rise (back waist to below belly) – Usually you’d measure a child’s rise from belly button to low back, via the crotch. In our case, you’ll still measure along the crotch but start at below the belly buldge (as with the waist, above) and end at the back of the waist. NOTE: Tiny Trainers have an extra few centimeters of “rise” to compensate for the lack of stretch in the absorbent core.

Thigh circumference (leg gussets) – Measure around the topmost part of your child’s thigh. Usually this part is narrower than the thigh itself.

(For Tiny Chaps ONLY) Height – Measure how tall your baby is from head to foot. Depending on your child's age it may be easier to lay them down on a flat surface to do this vs. trying to stand them tall. (Or taking a tip from my doctor's office: they mark lines head and foot on the exam table paper then measure that with more ease than a squirmy LO.)

Our Size Charts

Take your measurements and pop them into the Size Charts below. Remember, if in doubt, order the next size up.

Tiny Undies Size Chart

This size chart basically takes your measurements and matches them to our Undies, with the elastic already in mind. So, no further adjustments are needed once you’ve measured!

Tiny Trainers Size Chart

Use this size chart to match you baby's measurements to find the right size Tiny Trainers.

Tiny Boxers Size Guide

Boxers fit a little looser around the thigh, making them a favorite for many self dressers (both boys and girls). Follow the chart to find the right fit for your little one.

TinyUps Size Chart

TinyUps are designed to fit over Tiny Undies or Trainers. Typically babies 0-6 mos wear size Small, 6-18 mos wear Medium, and 18 mos+ wear Large.

Tiny Chaps Size Chart

Tiny Chaps are easy to fit, simply measure your child's height and waist according to the chart. The Velcro at the waist designed for quick removal also has the advantage of making them a little more adjustable.

Now that you know what size you need...let's get you some!