Pen Seb & Rox: Boys Underwear Review


My son being the only potty trained child in the house made making boys underwear the default choice for this project. Seb is a slim little dude and that can prove tricky when kids clothes, and patterns, have a lot of width to them; which is why I appreciate good sizing guidelines because I like to know what I’m getting into. When making each pattern I used the instructions included as a guide for selecting what size I made and if it was suggested to blend sizes I did. The guidelines for fabric were similar enough that I was able to use the same fabric to keep variations in fit not the fault of fabric choices but I am NOT comparing the patterns to each other.

The following chart contains information that may help you decide which pattern is right for you. If your child does not follow my own son’s build then your mileage may vary on the fit. After the chart is a summary of my own experiences making each pattern including my favorite and least favorite feature. The views expressed in the summaries are 100% my own.

undies table boys


All the patterns were sewn to fit Seb who currently measures 19 1/2″ waist, 21″ hips, 43″ height.

Pattern: Classic Briefs & Boxer Briefs by Peekaboo Patterns
Options sewn: classic briefs, faux fly
Size made: 18 months (hips), increased rise to 3t/4t


The Classic Briefs & Boxer Briefs by Peekaboo Patterns includes both a classic brief and boxer brief style. For the classic brief style that I made options included a faux or functional fly, accent trim, and instructions for “quick” and enclosed seem leg bands. For size selection I followed the instructions to use hips and to add rise. I went by the chart when cutting the band pieces and did not customize the fit further though it is suggested in the pattern to do such if needed.

Something sweet: I thought the information regarding fabric choices, cut pieces needed, etc. were laid out in a very clear and organized fashion in the tutorial. No fuss with the content or layout made it very easy to refer back to.

Something sour: I found the colors used for the pattern lines to be hard to see and would of been difficult to trace.

About the fit:I followed the information given in each size chart and even blended sizes when mentioned in the instructions. Fabric was chosen according to the pattern requirements and sizes made were chosen according to the included information.   The fit was amazingly close to Seb’s ready to wear undies and the pattern gets brownie points for including stretch percentage. I always second guess myself into oblivion when I don’t have numbers.

Pattern: Kiwiana Undies by Little Kiwis Closet
Options sewn: n/a
Size made: 54cm 21 ¼” (hips)


Kiwiana Undies by Little Kiwis Closet is a no-frills unisex brief with a liner. I chose the size according to the hip measurement

Something sweet: I thought the assembly method, which created the lining from the back and front pieces, was pretty snazzy.

Something sour: Since inches were included with the size chart I would have also liked to have seen them on the pattern pieces along-side the sizes in centimeters.

About the fit: Seb fell between two measurements and in accordance with the instructions, I sized up. After seeing the fit I would have personally sized down with the width and kept the rise the same since I felt that while they did fit, there was plenty of “room to grow” width-wise. I think Seb would outgrow the rise before he got wide enough to completely fill out the briefs without modifications.

Pattern: Lil Bug Undies by A Sparkly Baby
Options sewn: Did not use the optional liner.
Size made: 2 (ready to wear)


Lil Bug Undies by A Sparkly Baby come with an optional liner and knit fabric primer at the end of the tutorial. Size is picked according to ready to wear numbers and approximate finished waist.

Something sweet: I really liked the note about checking the pattern position so “Mickey does not appear to be sniffing your armpit”. Pattern positioning is something that I don’t always seen mentioned in patterns and can be a big deal.

Something sour: I would of liked to have seen hip size included on the chart for what size to make. Ready to wear numbers and possible finished waist size that weighs heavily on fabric used can be confusing if you do not have existing garments to use as a guide or previous experience working with the style.

About the fit: Seb’s store undies are marked 2T/3T and I pretty much guessed which way to swing since there was no 2T/3T on the chart.

Pattern: Pirates Booty Boxer Briefs by Patterns for Pirates
Options sewn: knit waistband, banded legs, functioning fly
Sizes made: 18 months (waist), 2t (hips), 4t (rise/length)


Pirates Booty Boxer Briefs by Patterns for Pirates is featured loaded with a functional fly, plain front, elastic waist, hemming, knit bands, and no-exposed seems. Most options can mixed and matched. For my pair I selected the function fly, knit bands for both the waist and legs. Using the size chart and instructions as a guide I blended between 18 months, 2T, and 4T.

Something sweet: Love all the pattern options! I’d like to see a similar pattern in brief style.

Something sour: Even with colors, specialized lines, and a pattern key – I still like size numbers at major points on the pattern pieces.

About the fit: I missed the step where you trimmed the main pieces down to compensate for the addition of the knit bands so I had to re-do the steps with the bands once I noticed that the rise was way too high. The width is great and the adjusted rise is fine but I wonder if I should have gone with a 3T for the rise. Might just be Seb’s proportions since he fell within the 4T range using the height chart.

Seb had no complaints about the fit of any of the pairs. He did disagreed with me over the boxer briefs counting as underwear (he said that they were for sleeping) but that is less about the pattern and more about the whims of a 4 year-old!

Roxanne is quite the fan of hat wearing and one of her favorite hats is her "sewing" hat. She learned from her mother who learned from her grandmother. Currently Roxanne is the official "Pattern Mistress" of the Pattern Exam. She lives in Massachusetts with her husband, son Sebastian, daughter Penelope, and two cats.