Tutorial: Box the Bottom Corners of a Bag

Lazies, I’ve put together a picture tutorial on how to easily and accurately box the bottom of a bag. 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 which you can use on lots of designs.

Lazy Girl Designs ‘With Love Tote’ with a 4″ deep boxed bottom.

Last week I announced our Make2/Give2 event for September which features our With Love Tote bag. You can get the pattern at this post. The pattern has been updated to include directions to make a flat bottom bag by ‘boxing’ the bottom corners.

Click the picture to enlarge. This is a view of the bottom of the bag.
The side seam (left) and bottom seam (right) meet and a seam is stitched across these seams to give the bag dimension.

– Cut a square from each bottom corner.
This is a 2″ square which will result in a 4″ deep boxed bottom.
The size of the cut square will determine the depth of the bag when boxed.

– Separate the layers of the bag at the cut corner.
– Pull the side seam and the bottom seam together, matching the seams, as shown here.
– Stitch closed.
– For extra strength, reinforce by stitching again.

The bottom of the bag takes shape as two corners are boxed.

Lay bag flat

Things to keep in mind
Cutting the corners will affect the width and height of the bag. The result will be a bag that is narrower across the bottom, and shorter top to bottom.
– Width of the bag across the bottom: 19″ minus 4″ (2″ for each corner), leaves the width at 15″ wide.
– Height of the bag at the side: 16″ minus 2″, leaves a height of 14″.

If you take too big of a cut at the corner, your bag might have odd finished dimensions. The larger the corner cut, the narrower and shallower the finished bag will be.

Some examples of corner cut sizes and finished bag sizes for this project
1″ corner cuts = 17″ wide x 15″ high x 2″ deep (wide, tall and skinny depth)
3″ corner cuts = 13″ wide x 13″ high x 6″ deep (square and deep)
4″ corner cuts = 11″ wide x 12″ high x 8″ deep (taller than wide and too deep)

Check our Craftsy pattern store for more projects!

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

Remember to box the cover and the lining so everything matches nicely. Refer to the With Love Tote pattern to see where and when in the project to do this.








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71 Responses to “Tutorial: Box the Bottom Corners of a Bag”

  1. Debbie — April 17, 2015 @ 2:19 pm

    I’ve been wondering about leaving the triangle of the corner and folding it so that it actually SHOWS on the outside of the bag.. Wd you know how to pull that off?

  2. benta — May 27, 2015 @ 5:50 am

    Thanks for this, hope it’s ok to link to rather than reinventing the how to for a bag post I’m writing

  3. Stacia Blau — August 3, 2015 @ 10:49 pm

    How do I finish off a large oval hole with another material? Want to use a different fabric and it seams to pucker and be weak at the oval edge.. Oval hole is about 6 inches.

  4. Vanessa Towns — October 19, 2015 @ 11:35 am

    Are there any tutorial for any of your bags.. with pictures?

    • Joan Hawley replied: — October 19th, 2015 @ 11:43 am

      Hi Vanessa, All of the designs are available as patterns with complete step-by-step instructions and photos!

  5. Rhonda — December 25, 2015 @ 11:50 pm

    Thank you for this fabulous tutorial. I was going to simply crochet around some fleece for a little blanket, but now I’m quickly putting together some messy navy stripe/my little pony fleece totebags for a pile of girls and I’m so excited to try these box bottoms. If I fail, the girls won’t know and if I succeed, wow, so many applications. Your pictures are amazing and I DID IT!!!!!!!!

  6. Cheryl — February 27, 2016 @ 3:23 pm

    Thank you for this. For whatever reason when I try to do it the “pinch, sew, and then cut” way my lines are never straight.

  7. Barbra — April 5, 2016 @ 3:37 pm

    I am in search of a pattern or directions for making a box bottom pouch that isn’t narrow at the bottom and wide at the top. I believe this happens when you “cut out” the little squares at the bottom as opposed to sewing across the triangle (you know, the other way to make the box bottom). I noticed your picture looks like the sides are straight all the way down, but it’s kind of hard to tell. Can you give me a little insight?

  8. Barbra — September 22, 2016 @ 5:15 pm

    Can you explain how the gusset or box bottom above reduces the height/width of the bag, based on a 16″ by 19″ bag…I am just not getting it, can you give more details please…thanks

  9. Barbra — September 29, 2016 @ 10:12 am

    Can someone please clear this up for me. I am getting conflicting info from different tutorials. When creating the “formula” for a tote, is the seam allowance part of the “square” that is cut out? Some sites say yes and some say no. Can someone please explain this in a simplified way for a beginner. I would like to know before I cut my fabric. Thanks so much.

  10. Barbra — September 29, 2016 @ 10:41 am

    Just to add what someone had written in regards to including/not including the seam allowances in the size of the cut out squares:
    “You would measure your one and a half box from the edge of the corner, including the seam in the box, because when you sew the new edge a half inch in you are adding the half inch seam allowance. So, while you are only cutting one inch into your bag, when you sew a half inch from the New edge it makes your seam one and a half inches, and your corner ends up a perfect three inches.”

    “you are absolutely right. If you want a 3 inch bottom the stitching line should be 1.5 inches from the original stitching, so I would only cut 1.25 inch square so you have .25 inch for the corner seam.”

    Thoughts anyone?

  11. Karen — October 1, 2016 @ 5:33 pm

    Thank you! I was just trying to figure this out for a bag to hang on the rail of a hospital bed. I never even thought of the width of the bag being affected, just the height. That would’ve been an epic fail.

  12. Andrea — October 3, 2016 @ 3:33 pm

    I have the pattern for the Becca Bags and am confused about the size to cut the material. It only gives one measurement, for example for Large Becca, it says Top Band 2 1/2″. What should the width be?

  13. Barbra — October 5, 2016 @ 7:50 am

    This is a wonderful tutorial. Does anyone know how to figure out a predetermined size of a tote? For example, if I want the finished size of my tote to be 18 width, 17 length, and a 5 inch box bottom, and using a 1/2 inch seam allowance with a 1 inch hem at the top., what size would I cut my fabric pieces, and what size square would I cut out for the bottom, based on the reductions that will take place as described above. I have searched and searched for this answer and can’t find it or help. It might be very simple, but I can’t figure it out. I made a tote the other day based on what I thought would be the correct formula, and it came out Gigantic. I would be ever so grateful if someone on here would respond. Thanks.

  14. Joanne — October 31, 2016 @ 5:08 am

    Now this was well explained. Thank you for these perfect illustrations, explanations and various examples. They will come sooooooo handy. Again ty 😉

  15. M — January 26, 2017 @ 10:39 am

    This is awesome! Makes perfect sense and will result in a much nicer finish that the ‘pinch the triangle’ method. I have no idea why I had not thought of this before or seen it anywhere. Love it! Thanks so much or sharing!

  16. Brenda — May 21, 2017 @ 9:45 pm

    Do you mean to measure on the stitch line to cut out for the corner?
    Cut a square from each bottom corner.
    This is a 2? square which will result in a 4? deep boxed bottom.
    The size of the cut square will determine the depth of the bag when boxed.
    Thank you B.

  17. Brenda — May 21, 2017 @ 10:07 pm

    I am a little confused. Do you measure
    the stitching line to cut out for the box corner or measure from the raw edge of the fabric? Thank you

  18. Gloria Baffrey — May 27, 2017 @ 5:34 pm

    I am sewing a purse with 12″ vynil bottom length. Everytime I sew the box, it comes out 8 inches and looks unproportional. What should I do.

  19. IDoreen — July 9, 2017 @ 2:40 am

    I would like to buy two patterns please .The Box the Bottom Corners of a bag.

  20. Keri horn — July 24, 2017 @ 8:08 am

    Well I wish I knew this last night. This is a whole lot easier than sticking your hand inside trying to feel for the seams and hoping and praying it works thank you so much!!!!!!!