How to Make a Backpack-Dufflebag Convertible

Wouldn't it be great if there were a backpack you could use for everything? Maybe a gym bag that converts into a purse or a backpack if you need more room? Well if that's what you're looking for, then look no farther, because the backpack-dufflebag convertible is exactly that! This is a backpack with movable straps and a duffle bag stowed in the compartment at the bottom. When you want to spice thing up, you can unzip the compartment and fold the backpack into the duffle! The straps are also movable, so you can tote this sack in 5 different ways. It is most spacious when in backpack form.

Simply unclip the straps and pull them out of the backpack, then unzip the bottom compartment to release the duffle bag. The backpack fits into the duffle, with room to spare. You can reattach the straps at each end to make a cross body bag or in the middle to make two handles. You can also put the straps diagonally across the backpack to make a cross body backpack.

I started designing this bag after reading about a fictional limitless bag that could hold anything. It may be impossible to have an infinite handbag, but what if there was a handbag that contained even more space??? And the design evolved into a 2 in 1 carrying container.

This is my first instructable, so it may have some bugs. That's why some pictures are upside down. If you have any suggestion or questions about anything, please leave a comment!

This project requires some sewing skills. I've included explanations for jargon in the instructions for ambitious beginners. Experienced sewers can skip these explanations.

Step 1: Materials and Equipment

The project demands:

  • 1.5 yards of sturdy, woven fabric. I used denim and canvas.
  • Some sort of paper on which to draw the pattern cuttouts
  • Strong thread
  • A 10"x 20" and a 2"x 38" piece of foam padding or some other support. I used double layered industrial bubble wrap.
  • Bias Tape
  • A 55 cm (22") zipper and two 80 cm (32") zippers, all separating.
  • 84 inches of webbing, one inch wide
  • 6 D rings with an inner diameter of one inch
  • Two swivel clasps on D rings with an inner diameter of one inch
  • a sewing machine and supplies

You might have noticed interfacing isn't included. That's because most high stress areas on the bag are already reinforced by another component of the bag. For example, the compacted duffle back helps support the bottom of the backpack, and the backpack distributes the weight of transport in the duffle.

Step 2: Cutting the Fabric

Below are the pattern pieces you need. They are all rectangles, measured in inches.

  • A Back 14X 22 cut two. You will sew these around the padding and then cut off the margin, so it ends up being the same size as piece B, the front.
  • B Front 21X 12
  • C Bottoms 12X7 cut 3. There will be one on the backpack, one on the duffle, and on the duffle-storing compartment
  • D Thicker Part of the Sides 31.5 X 5. This goes along the top and sides of the bag, zippered to piece E. Piece D has a fold that hangs over the zipper to hide it while the zipper is exposed on piece E.
  • E Thinner Part of the Side 31.5X4
  • F Lower Side 12 X 7, cut 2. This incidentally has the same dimensions as piece C, so you can use the same template
  • G Strap 6 X 39. This wraps around the foam in the strap. The bag has one long strap instead of two.
  • H Duffle body 39.5 x 22. One side of the duffle folds over the zipper to protect it, like piece D
  • I Compartment Cover 39X3 cut 2

I recommend drawing the patterns on paper and transferring that to fabric because I find it difficult to keep fabric from stretching while drawing on it.

I made pieces A,B, 2 of C, I and J out of canvas and the rest from denim.

Before you cut your fabric, make sure it is pressed flat! You may not be able to iron your finished product depending on what you use as padding.

Step 3: Assembling the Back of the Backpack

Once the padding is in place, the back of the backpack becomes less easy to maneuver while sewing.

  1. Sandwich your padding between the two piece A's, with the wrong sides together (picture 1). In other words, you have two pieces of fabric that will become that back of your backpack, along with the padding, and these fabric pieces probably look different on each side. The side we prefer looking at is called the right side, and so the other side would be the wrong side. You want the right side to face outwards on your final product, so people can see it, and the wrong side to be hidden on the inside. Lay one of these pieces on the ground (or table, if you are more sophisticated than me) with the right side facing down, and put your padding on top of that. Try to center it, but it's okay if the padding is slightly closer to one side that the other. Put the other fabric piece on top of that, with the right side facing up.
  2. Pin your sandwich so it doesn't wiggle. Start with one pin in the center that goes through all three layers, then pin to the edges of the padding. If you can't force a pin through the foam, pin it to each layer separately. In picture 2, I started at the edges, resulting in a wrinkly, loose back. Don't be like me and keep it taut while you pin!
  3. Sew around the padding (picture 3, results in picture 4). Go as close to it as possible. You don't want it to slide around.
  4. If you can, sew across the padding a couple times to steady it.
  5. Cut half an inch from the seam the padding (demarcated in picture 5).

Step 4: Sewing in Zippers

We're going to sew one zipper between pieces D &E, one between the pieces I, and one that spans both ends of piece H so you can zip it into a loop. Let's start with piece D and E.

Piece D has a fold the covers the zipper. You make this by pressing under 1.5". In case you are new to sewing, here is the more comprehensive guide: lay piece D flat on its right side and fold one side of the long end overlaps by 1.5 inches (picture 2). Pin this in place and press it with an iron so the fold remains after the pins are removed (picture 3). Don't put pins so close together that you can't iron between them. Most people remove the pins as they press to avoid ironing directly on the pins. If you don't know what temperature your fabric needs or if it handles steam, check here.

Next you put an 80 cm zipper along the folded part so the teeth face the fold and the side of the zipper is flush with the raw edge and sew this in place with double fold bias tape. Have the top-stop be an inch from the end. In other words lay piece D on its right side and open the folds you just pressed. Making sure it's smooth, pin the zipper along the edge you've pressed, so the zipper tape is right against the fraying edge, and the teeth point to the middle of the fabric. The top of the zipper teeth should be an inch from the top of the fabric. It's okay if the zipper is longer than the fabric. Wrap the bias tape around the raw fabric edge and zipper tape (picture 5 and 6) then sew it all together (picture 7 and 8). This video shows you how to use bias tape. It starts using double fold tape at 4:35.

Now repeat this process on piece E, but fold over 0.5 inches instead of 1.5. Before you sew, place the pined zippers side by side to ensure you're sewing them in the right positions.

Nextt, do piece H. You'll fold one of the shorter sides (the sides that are 22" long) by 1.5" and the other by 0.5 inch (picture 9). Use the 50 cm zipper for this. Make sure the zipper heads are pointing the same way, so you can zip them together without twisting piece H. The loop formed when you zip them together will be your duffle bag.

Last you'll add a 50 cm zipper to the two piece I's. Fold both of these by 0.5 inches, as there is no overhang and this zipper is exposed. These two pieces are identical, so it's easy to sew the two halves of the zipper on in the same way, and be left with zipper teeth pointing to the same direction, which means they can't zip up. Before you sew, place the pieces next to each other and make sure the teeth point to each other.

Step 5: Putting It All Together

    This is where the fun really starts. We're going to put the bottom of the duffle bag in place, then stitch sides of the backpack together, attach that to the back, and then attach the front. After that, we can sew the two bags together.

    This involves sewing through several layers of fabric (at least 5) at once. Doing this with thick fabric is not easy and could knock the mechanics of your machine out of synchronization if you attempt to quickly sew through strong material. Getting it fixed isn't cheap, trust me. Read this advice on sewing through multiple layers before you attempt it. Use a thicker needle, like one made for denims, and heavy duty thread.

    The seam allowance is 1/2". You can use whichever seam you like. Bias tape would be a good choice, as it is how most seams in professional backpacks are made. I had to use plain seams due to time constraints, but would have preferred bias tape or French seams. Don't forget to attack both pieces F. You've now constructed the sides of the backpack.

    Lay piece H flat on its wrong side and cut notches in the fabric at 5, 11, 17, 23, and 29 inches from the fold (like in picture 1). These notches are straight snips into the fabric, less than 1/2" they will guide us when folding the bag together, help piece H contort around piece C, and will be entirely hidden in the seam allowance when you're done. On piece C I drew the 1/2" seam allowance and a marker in the middle of the long in pen (picture 2).

    Place the right side of piece C on the right side of piece H, so the seam allowance marks fall directly upon the 11" and 23" notches, and the middle-of-the-long-side mark is directly above the 17" mark. Pin these together, then rotate piece C so another drawn corner goes to the 19" notch. Pin that in place and rotate it the other way so the final corner fall on the 5" notch. Now place the two zippered ends of piece H along the long, unpinned side of piece C. They should overlap somewhat, and the side with the overhang will go between piece C and the other zipper. Once everything is secured by pins, you can sew along the drawn line (picture 3) to make the duffle bag.

    Now onto the sides of the backpack. Zip together pieces D and E. Place the right side of this on top of the right side of piece F (picture 4). Sew the short ends of these together.

    Make 2 notches on piece D, 20.5" from the end of each piece E. Pin these notches on top of the corners on the back (piece A) so the right side of D&E is against piece A. Continue pinning the sides together (picture 5). I drew the seam allowance on to the wrong side of D&E, but you don't have to. If the edges of A are flush with the edges of D&E, the seam allowance should fall directly over top of the seam on the back and you sew ontop of the old seam (pictures 6 and 7). If you turn this right side out, it should look like picture 8.

    Cut the notches on the other side of piece D and repeat the process with piece B. Turned right sides out, it should look like picture 9.

    Now it's time to attach the backpack to the bottom of the bag and the duffle. It's much easier to affix the first 2 and sew the duffle in place after than to put everything together at once, so that's how we'll do it.

    Take one of the piece Cs and draw the seam allowance on the right side. Once again, this isn't necessary, but it helped me. Also, if you cut out the squares out of the seam allowance corners (as in picture 17), it will be much easier to sew everything together. I regretted not doing this. Pin the sides of piece C to the bag so that all right sides face out (picture 9). When you get to the seams of the backpack, point them towards the sides of the bag, like in pictures 9 and 10.

    Take your I pieces and cut markers at 3.5 14, 20, and 31.5". Fold each I piece in half with right sides together and sew the short ends (picture 11, which is upside down for some reason). Put one of the I pieces around the bottom of the backpack so the right sides are together and raw edges line up (pictures 13 and 14, which is of the next step). The seam on piece I should be in the middle of the side. When pinning these together, try to get the raw edges to line up and stack as perfectly as you can. Sew these layers together.

    Attaching the duffle to the backpack can be awkward. To make this easier, I did up the zipper on piece H and tied it together, as in picture 14. You're going to sew the right side of piece C (the bottom of the bag) to piece H. Start by pinning the 5" & 29" notches to the front corners of the backpack and the 11" & 23" to the back corners (picture 15). Secure everything well in place, especially the area with the zippers, before you sew this. I found it easiest to sew each side of the bag individually. I sewed the back, between the 11" and 23" notches, then the sides, between the 5" & 11" notches and the 23" & 29" notches then I sewed across the front. When you're done, it should look like picture 16. Don't sew over the zipper, as that could break your machine's needle.

    You've completed the hardest part! Next is the compartment cover. Get your final piece C ready by drawing the seam allowance on the wrong side and cutting squares out of the corners (picture 17), if you so wish. Mark a line in the middle of the short side of piece C and lay the seam on piece I directly above that, right sides together (picture 18). Pin the 3.5"& 31.5" notches to the corners of piece C, then the 14 & 20" notches to the other corners. Sew these pieces together and you should have something that looks like pictures 19 and 20.

    Step 6: Adding Attachments for the Strap

    Take the webbing and cut out six 8" segments and six 6" segments. Fold the 8" segments into loops by overlapping 1.5 inches, like in picture 1. Fold the 6" segments in half and slide a D ring onto each one (image 2).

    I had to sew the webbing by hand because it created to much resistance for my machine.

    Place one of the 6" segments in the bottom right corner of the backpack bag. Sew it in place by making a square around the edges of the webbing (look closely at picture 3. The thread is the same colour as the webbing). You only need to fasten the bottom part of the webbing, so the top can bend freely. For extra reinforcement, sew an X across square. Add another piece of webbing to the bottom left corner (image 4).

    Now sew the 8" loops on the top of the bag, like in pictures 4 and 5. Make sure you sew the square where the webbing overlaps, or one side of the webbing segment could come loose. The exact placement of the webbing is up to you. I put mine 2 inches middle the side of the bag and 1/2 inch from the back. Once you're done this, your bag will look like images 5-7.

    To add the webbing for the duffle bag, expand the duffle bag around the backpack. Get two 6" segments with D rings and pin them on bottoms (on the piece C's) so they stick up over the edge, as in pictures 8. Make sure they are in the middle of piece C so the bag does not tilt to one side. I sewed the on at the top of the zipper first (image 9). Sewing the one at the lower part of the zipper, closer to the backpack, involves reaching through the backpack and duffle bag. You can roll the front of the backpack up and temporarily pin it out of the way(pictures 10 & 11).

    The placement of the four side strap attachment sites is up to you again. I wanted mine to divide the bag into even thirds, so I attached the webbing 7 and 14 inches from the side seam, like in image 12. You want the webbing to be sewed onto the sides of the duffle, not the top, so make sure it is at least 6" from the zipper. Fix two 6" segments at the top end and two 8" segments at the bottom, so there is a loop and a D ring on each side of the zipper. If you put both loops on the same side of the zipper, the strap will not work properly.

    Step 7: Creating the Strap

    First, sew a seam finish along the short ends of piece G. The simplest way to do this is a zigzag stitch very close to the edge or to trim it with pinking shears, the scissors that make zigzag cuts. Fold the fabric in half along with short sides with the right side facing inwards (image 1). Sew along the long edges 1/2" in (image 2). Turn this inside out (image 3) and stuff it with the 2"x 38" padding. Slide the padding to the center of the fabric tube and rotate it so the seam is on the side (image 4). Stitch straight along the center of the padding (also image 4). Do this slowly and remember the guidance on sewing through thick materials. Once you are done, fold the circular edges of the fabric tube inwards 1/2".

    Put the remaining segments of webbing through swivel clasps rings and fold them in half (image 5). Place the ends of the webbing into the tube and pin in place. Sew across the folded tube, so you have something like image 6. Do this on both sides of the tube.

    Clip the strap to any D ring and you have your own convertible backpack-dufflebag. Go out and show off this awesome 2 in 1 bag!

    I hope you enjoy this instructable. If you make this project or have any questions, let me know.

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      Penolopy Bulnick

      4 months ago

      Fun idea making a convertible backpack :)