How to Make Perfect Box Bottom Corners on a Bag Every Time

Easily box the bottom corners on every bag you make with this step-by-step free sewing tutorial.


Lazies, Easily and accurately box the bottom corners of your next bag creation with my step-by-step sewing tutorial. A box bottom means the bag has a flat bottom, making it easier to hold wide things or rest comfortably when you set it down. This is an easy technique to use on lots of designs. I incorporate this technique in a number of my Lazy Girl Designs sewing patterns, too. Be sure to grab a FREE (a $9.95 value) printable tutorial below

Close-up showing the finished boxed corner of a fabric bag.Lazy Girl Designs ‘With Love Tote’ with a 4″ deep boxed bottom.

Box Any Tote Bag or Purse Pattern Project

This tutorial uses our free With Love Tote bag pattern. Here are two totes showing boxed corners on the top tote and a flat tote on the bottom. You can grab the FREE Tote Bag pattern here.

With Two red batik fabric tote bags made from the With Love Tote Bag Free sewing pattern.

Here’s a close-up view of the boxed corner from the image above. The side seam (left) and bottom seam (right) meet and a seam is stitched across these seams to give the bag dimension.

View of the boxed bottom corner of a fabric bag showing where the side seam and bottom seam meet.

How Boxing the Bottom Corners Affects the Bag Size

Boxing the bottom corners to give a bag a flat bottom to stand on ‘steals’ from the width and height, changing the size of the finished bag. The result will be a bag that is narrower across the width of the bag at the bottom seam, and shorter in height along the side seam from top to bottom.

  • Bag size before boxing corners: 19″ W x 16″ H (flat bag has zero depth)
  • Bag size after boxing corners: 15″ W x 14″ H x 4″ D
  • Width is the length of the remaining seam across the bag bottom: 19″ – 4″ = 15″
  • Height is the length of the remaining side seam: 16″ – 2″ = 14″
  • Depth of the bag is the length of the boxed corner seam: 4″

Close up view of showing seam allowances meeting at the bottom of a fabric bag.

1. Determine Desired Size of the Boxed Corner

Small changes in the size of the corner cuts make a big difference in the finished size of the project. If you are unsure of how big to cut a square to box the bottom corners to give your bag depth, start with a smaller cut, sew, then see what you think. You can always cut more off and stitch again.

  • Our tutorial shows a 4″ deep boxed corner.
  • Divide the desired 4″ depth by 2 = 2″
  • 2″ is the size of the square that will be cut off of both bottom corners.

2. Mark and Cut Squares From The Bag Corners

  • Flatten project and align it with the grid on a cutting mat.
  • Mark a 2″ square on both bottom corners.
  • Cut the marked square from each bottom corner.

Close-up showing a corner cut out of a fabric bag.

For more free sewing tutorials, follow my Pinterest board Free Sewing Tutorials, Tips & Hacks

3. Open and Align Seams of the Bag at the Cut Corners

  • Reach into the corner and open.
  • Bring the side and bottom seams together, matching the seams.

Close-up showing how to bring side seam and bottom seam together to box the bottom corner of a fabric bag.

4. Stitch Closed to Box the Bottom Corners

  • Stitch through all layers along the cut edge to close the corner.
  • Backstitch at the beginning, where the seams match, and at the end.
  • If desired, reinforce by stitching again for extra strength.

Sew across the cut corner to box the bottom of a bag.

5. Finishing Details

Here’s a full view of the seams at the bottom of the bag after boxing the corners. Remember to box the bottom corners of the lining, too. Turn your project right side out and press. Improve your pressing skills with my Pressing Tips for Professional Results.

Close up view of sewn boxed corners showing seam allowances meeting.

Give your bag more support with my trick for Easy Sew-In Bag Support.

Need a better ironing board? Check out the IKEA Hack Pressing Station of my Dreams.

Boxed Corner Cut Sizes and Finished Bag Sizes for This Tote Bag Project

Here’s how different size corner squares affect the finished size of our sample project.

  • 1″ corner = 2″ deep. 17″ W x 15″ H x 2″ D (wide/tall/skinny, fits a large text book)
  • 3″ corner = 6″ deep. 13″ W x 13″ H x 6″ D (square/deep, fits a shoe box on its side)
  • 4″ corner = 8″ deep. 11″ W x 12″ H x 8″ D (short/deep, fits shoes without the box)

Close-up showing the finished boxed corner of a fabric bag.

Show Me Your Boxed Bag Creations!
Share pics of your bag projects in my Facebook Lazy Girl Group

That’s Pinterest-ing!
Follow me on Pinterest and pin this post to your Pinterest boards.

How to box the bottom corners of a bag.

Remember to grab the FREE printable tutorial below.

Subscribe to receive emails for my blog and newsletters about new patterns and project ideas.

Joan’s Sewing Group | Pinterest

Download this Freebie

Enter your email address below to instantly download this freebie now!

  • © Lazy Girl Designs. For personal use only. Please do not distribute these downloadable files. By clicking the button below you agree to these terms.

  • This field is for validation purposes and should be left unchanged.

Like and share this post with your stitchy friends.