How To Draft A Back Bodice Sloper: Update

slopermain image How To Draft A Back Bodice Sloper: Update

I cannot express the importance of a sloper. A sloper, or a block, is a basic pattern (bodice, sleeve, skirt, pant, or dress) that is made to fit a particular individual, size, or mannequin exactly and perfectly. It’s like a second skin with just a tad of wiggle room. It has minimal darts and is usually sewn with muslin or some other light-weight cotton fabric. From this pattern, other patterns can be drafted by manipulating the pattern (unless the design requires draping, in which case the pattern is made by draping and then trueing). A sloper is also a tool to use throughout the design process because when patterns are manipulated, shapes can become distorted and it’s a good habit to compare the shapes of the manipulated pattern to the shapes of the sloper pattern so that the original pattern shapes are maintained as much as possible. Throughout the design process, I’m constantly going back to see that the armhole depth/length/shape is as close to my sloper as I can get it. A sloper is also a tool to use when dealing with commercial patterns – you can compare specs and pattern shapes and adjust the commercial pattern as needed so that it is as close to your sloper as possible.

My method differs from a textbook’s sloper drafting method in the amount of ease that is built into the pattern. If a sloper is supposed to be the closest approximation of your body in fabric form, why add 2” of ease (this is what every textbook I have read suggests)? A sloper should be form fitting but also moveable and the amount of ease I build into the sloper pattern gives just enough wiggle room to allow easy movement while still being fitted.

Assuming that you used my tutorial on how to draft a front bodice sloper, then you’re ready to draft the back. Let’s get started.

measurements2 How To Draft A Back Bodice Sloper: Update

First, we must measure and record a couple of measurements. Just like I cannot express the importance of a sloper, I cannot express the importance of accurate measuring. Ninety-nine percent of the time, reader’s questions are answered by correcting their measurements. It’s not the drafting method that is incorrect – it is their measurements.

The first steps to measuring are determining who will take the measurements and time. I highly recommend that someone measures you but measuring solo is not impossible. If measuring solo, be sure to stand in front of a full length mirror while measuring and be sure that the measuring tape is level while measuring. I also recommend setting an hour aside to take all of your measurements. Spend one hour to get accurate measurements or spend six hours remeasuring yourself and redrafting your sloper because accurate measuring was not done on the first go.

The second step to measuring is wearing the correct clothing. Wearing only undergarments will yield the most accurate measurements but if someone will be taking your measurements, it is okay to wear workout/exercise clothes such as leggings and a tight tank top. Also, make sure that you wear the same bra while measuring and throughout the sloper fitting process.

Whether you wear undergarments or exercise clothes while measuring, I also recommend that you mark your CB line, shoulder line, shoulder tip, neckline, armhole depth, side seam, and waist line with a marker, pen, chalk, or pins. You can eyeball all of these measurements except for shoulder tip, armhole depth, and waist line, which I will show you how to find below. This will keep measuring points consistent throughout the measuring process.

Stance and breath is also important while measuring. Be sure to stand upright, on a flat surface, with feet slightly apart, and with weight distributed evenly. Also, breath normally while measuring as any large inhales or exhales can distort measurements.

Before taking any measurements, a waistline must be defined. To find the waist line, tie a string, shoelace, or tie around your waist – don’t tie it too tight or too loose; tie it just right – and wiggle around to let the string fall to your natural waist.

Now we can measure! Measure and record the following measurements anduse the diagram where applicable (for very simple measurements, I did not include a diagram).

{CB LINE} line perpendicular to prominent bone at nape of neck (TOP of back neck)

{FULL LENGTH} shoulder at neck to waist line

{CB (CENTER BACK) LENGTH} prominent bone at nape of neck to waist line

{SHOULDER TIP} ¼” from the end of shoulder (if you start to raise your arm, a hollow will form at the shoulder joint. This is shoulder tip – approximately)

{SHOULDER LENGTH}  shoulder at neck to shoulder tip

{ACROSS SHOULDER} shoulder tip to shoulder tip – MEASURED on back – and DIVIDED by 2 (across shoulders for both front and back bodice sloper is taken on back)

{SHOULDER SLOPE} CB waist line to shoulder tip. Be sure to keep measuring tape taut and to extend it straight from waist to shoulder tip

{SIDE SEAM LENGTH} armhole depth to waist line

{BACK NECK} tie a chain/tie/elastic loosely around the neck and allow it to rest at the neck base. Then measure from CB neck (prominent bone at the nape of the neck) to shoulder seam along curve

{BACK ARC} CB to side seam/AH (ensure that measuring tape in level and perpendicular to armhole base/CB line)

{ACROSS BACK} CB line to armhole at approximately 5” DOWN from shoulder seam/neckline (remember to mark armhole line with marker, pen, pins, etc). A way to cross check this measurement is to subtract ½” from across shoulders. Example: If your across shoulders is 14,” is your across back in the range of 13 ¼ – 13 ½”? Across back and across shoulders have a standard relationship that ensures the armhole is a smooth curve from shoulder seam to the base of the armhole on both front and back. I posted about this relationship here.

{WAIST ARC} CB line to side seam along waist line
sloper1  How To Draft A Back Bodice Sloper: Update

STEP 1:

A-B: Full length

A-C: Across shoulders, squared from A

Square a line down 7” from C. This will be a guideline for drawing armhole

B-D: Center back length

Square a line out 4” from D. This will be a guideline for drawing neckline

sloper22 How To Draft A Back Bodice Sloper: Update

STEP 2:

B-E: Square a line out from B equal to waist arc plus 1 ½” (for dart)

B-G: dart placement, measured out from B

G-H: 1 ½”

G-I: ½” G-H

B-J: Side seam length (on B-D line)

J-K: Square a line out from J equal to back arc plus 1/8” for ease. It may not seem like a lot but 1/8” on front and back pattern will be ½” in the round.

J-L: B-I

L-M: ¾” squared down from L. This will become dart point

Draw dart legs by connecting point M with points G and H and extending line down 1/8” at each point. After, draw a curved line from point G to B and point H to E using a curved ruler. Ensure that waist line intersects side seam and CB at a 90 degree angle.

step 32 How To Draft A Back Bodice Sloper: Update

STEP 3:

B-N: Shoulder slope with N falling on C guideline

A-O: Back Neck

Draw a line from N to O. If this measurement does not equal shoulder length plus ½” for dart, it is okay to extend or shorten the line accordingly. Be sure to extend/shorten the line near the C guideline (do not extend or shorten the line at the neck). You do not want to change back neck width because just as with across shoulders and across back, front and back neck width have a ‘standard’ relationship which I’ve posted about here.

Square a line down from O to D guideline and label P. O-P line should be perpendicular to O-N line

P-Q: ½” diagonal line (45 degrees) from P

Using a curved ruler, draw neckline with line touching points D, Q, and O. It is okay if line does not follow O-P line exactly near the intersection of the shoulder seam at neck. Back neckline connects with front neckline and it’s more important that the neckline is a smooth curve from CB to CF or vice versa. But it is important that necklines intersects CB at a 90 degree angle.

O-R: ½ O-N

With a ruler touching points R and M, draw a line 3” down from R and label S. This will be shoulder dart point

Mark T by measuring ¼” out from R (on O-N line towards neck) and square up 1/8”

Connect T with points O and S

Mark U by measuring ¼” out from R (on O-N line towards AH) and square up ¼”

Making sure T-S and U-S are of equal lengths (adjust as needed) and connect U with points S and N

sloper 41 How To Draft A Back Bodice Sloper: Update

STEP 4:

Draw a line from K to E

K-V: ½” down from K on K-E line (this will become bottom of armhole)

D-W: ½ of D-J plus ¾”

W-X: Across back plus 3/16” for ease (plenty of room to raise arm up and in front of you)

Using a curved ruler, draw armhole. First, draw the top of the armhole with curved ruler touching points N and X and then draw the bottom of the armhole with curved ruler touching points V and X. After, eyeball and true the shape. The armhole should curve slightly inward from shoulder seam to mid-armhole and then scoop to meet the side seam. The armhole should intersect side seam at a 90 degree angle. This will ensure that back armhole transitions well to front armhole and that the base of the armhole is flat. But it is okay if armhole does not intersect shoulder seam at a 90 degree angle. Just like neckline, back armhole will connect with front armhole at the shoulder seam and it is important that it transitions well. 

Lastly, true the shoulder seam by folding the dart closed (making sure dart intake is pressed towards CB) and redrawing shoulder seam so that it is a smooth line from neck to shoulder tip.

tags: Pattern Making Comments: 30

30 Comments
  1. Cynthia Pyatt

    Thank you for these posts! I’ve been wanting to draft a sloper to help me get a better fit!

    Reply
  2. sallieforrer

    Thanks again Maddie! This is on my New Years Resolution list!

    Reply
  3. Maggie

    I attempted to do this a few years back from a book I have with not much success. After reading this, I will have to give this another whirl using your instructions. Thanks for doing this series, I think it will help a lot!

    Reply
    • Natasha Estrada

      The books are terrible aren’t they. The author of one of the most widely used books teaches locally and I’ve often thought about taking her class to see why she wrote what she did. I took sketching by the lady that wrote 9 heads and one look at her and you can understand why her drawings look like they do so was hoping there might be some ahhah moments to be found.

      Reply
  4. Miranda

    When I get a bit of time I’m going to make this happen. I drape more often than pattern making from a block, because I’m often sewing for others. But making myself a sloper will definitely save me some time in the future!

    Reply
  5. Kerry (Kestrel)

    Wow this is so thorough and I really need to do this as I’ve been having such problems fitting for a broad upper back. Thanks for sharing all this information.

    Reply
  6. Hazel

    I really love these posts Maddie, your instructions are so clear and easy to follow. I’m hoping to start drafting my sloper in the next couple of weeks to use as a base for lots of projects! Thanks for sharing :)

    Reply
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  8. Theresa

    Thanks for this post. I’m really excited about trying this later today. One question. B-G is listed as “dart placement, measured out from B”, but I don’t see how I know where to place the dart. I’m sure there is something simple I am missing, so would be grateful if you could clarify.

    Reply
    • Maddie

      Theresa, dart placement is a standard measurement – 3/4″ less bust span. Does this make sense?

      Reply
      • Theresa

        Yes. I noticed it as soon as I got to that point on the front. Thanks for the quick reply!

        Reply
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  10. Jonnytsunami

    “Draw a line from N to O. If this measurement does not equal shoulder length plus ½” for dart, it is okay to extend or shorten the line accordingly. Be sure to extend/shorten the line near the C guideline (do not extend or shorten the line at the neck)”

    My N-O measurement was shorter than my shoulder length measurement+1/2″ . So I moved point N down ON the C guideline and marked where my tape hit the shoulder measurement. Is that what you meant by extending or shortening the line accordingly?

    So if I was holding one end of my measuring tape on O, would I just move N down the C guideline until my tape hit the shoulder measurement?

    Can’t figure it out for the life of me :-/ would appreciate your clarification. Thanks in advance for your help.

    Reply
    • Maddie Flanigan

      If your N-O line was shorter than your shoulder length + 1/2″, then you would shorten the line as shown in the diagram (red line). When making this change, be sure that the length of B-N is maintained (shown by blue line on diagram) so that you don’t change the shoulder slope. Does this make sense?

      Reply
      • Jonnytsunami

        Thank you SO much! Yes, it totally makes sense with the diagrams-they’re great! However, im really dyslexic and will probably have more issues when I get home to work on it.

        Thank You!

        Reply
      • judy

        Hi Maddie – this is a really great place to learn; thanks for all the wonderful posts! – I did quite OK on the front sloper (the paper thing feels like it might fit), but N-O on the back is driving me crazy…I really think my measurements are correct (full back 18.5, shoulder slope 17.7, back neck 3.6), but N-O is just ridiculously short on my pattern, and when I try to lengthen it to fit my shoulder measurement + 1/2″ (I figure that’s what I need to do, or am I wrong there?), I can’t get it anywhere near that line down from C…
        Actually, I didn’t quite get what you mean in the diagram above, because the new B-N isn’t the same length as before. The thing that has remained the same is the distance from A-C. But even if I try to maintain THAT distance, my new N would be pretty far right from the line down from C (about 2 inches or so). What to do???

        Reply
        • Maddie Flanigan

          Judy – I’m glad the front sloper turned out well, at least from what it seems.

          It’s okay if when you lengthen the N-O line to equal shoulder length plus 1/2″ (for dart) that is doesn’t meet the C guideline and that B-N isn’t the same length as before. What’s important is that the front and back shoulder lengths are the same because if they aren’t one will be longer than the other when you sew them together. Does this make sense?

          Just curious, what is your across shoulder measurement (A-C)?

          Reply
  11. DoLo

    Thanks a lot for your tutorials, Maddie, they are really great! I can’t figure out how to draw the line B-G in step 2, because I only know the length of the line B-G, but G is not lying on the line B-E. Would you mind explaining it again? I would really appreciate your help. Thanks in advance!

    Reply
    • Maddie Flanigan

      I’m glad my tutorials are helping you!

      Maybe an example would answer your question best. Let me know if this makes more sense.

      Pretending that B-E is 6 inches, draw a line perpendicular from B that is 6 inches and mark the endpoint point E. Now pretend that B-G is 3 inches (B-G, or dart placement, is always 3/4″ less than bust span on both front). On that same line, mark where 2 inches is from B – that is point G.

      Reply
      • DoLo

        “On that same line, mark where 2 inches is from B – that is point G.” Do you mean on the line B-E? So G is actually lying on the line B-E? And why do you take 2 inches if B-G is 3 inches? Sorry for the many questions.

        Reply
        • DoLo

          Ok, I think I understand now. The points G and H are first on the B-E line. But then you fold the dart closed and redraw the waist line in order to make it smoothly. As a consequence the ‘new’ points G and H are no longer on the line B-E in your drawing.

          Reply
          • Maddie Flanigan

            Yes, points G and H are first on the B-E line but at the end of step 2, the tutorial states,

            “Draw dart legs by connecting point M with points G and H and extending line down 1/8” at each point. After, draw a curved line from point G to B and point H to E using a curved ruler. Ensure that waist line intersects side seam and CB at a 90 degree angle.”

            This is how you get the new points G and H that are no longer on the line. Does that make sense?

          • DoLo

            Thanks, Maddie, it makes perfect sense now!

  12. twiglet

    Hiya, Thanks for the pattern tutorial!

    I did the front sloper on paper and had to adjust it via the comments because i am petite. I then drew the back sloper on paper but the armhole looks huge compared to the front pattern, and there are no instructions to adjust the back pattern for petite…also the side seams don’t marry up in length, wondering if I have missed something somewhere that I should have done?….Thanks so much hope you can help!

    Reply
  13. pinkpassion

    Thanks for this!! wow, pretty much what I needed. But I really just want to make a very basic henley long sleeve tee and possibly with a placket in the front. Do I still need to add the dart?

    Reply
    • Maddie Flanigan

      I’m glad you found this tutorial helpful and I love the idea of making a Henley. But I have a couple of questions. Will your henley be a knit or a woven? This tutorial is for a woven and doesn’t factor in the stretch of the fabric henley’s are usually made with. Also, what dart are you referring to? The bust dart, the shoulder dart, or the back waist dart?

      Reply
  14. Guest

    “Making sure T-S and U-S are of equal lengths (adjust as needed) and connect U with points S and N”

    I got the U-S line shorter than T-S. How do I adjust this, please?

    Thanks!

    Reply
  15. Anahi

    “Making sure T-S and U-S are of equal lengths (adjust as needed) and connect U with points S and N”

    I got the U-S line shorter than T-S. How do I adjust this, please?

    Thank you so much!

    Reply
    • Maddie Flanigan

      you would extend line U-S up until it was the same measurement/length as T-S

      Reply
  16. Jill Justice

    First of all thank you for all of these incredible tutorials and resources. Secondly, if you’re still answering questions on here, maybe you can help me get past a problem. I’m finding that X comes out further than K making the armhole the wrong shape. I have remeasured everything and here are the numbers I am working with.

    J-K Bac Arc plus 1/8″ = 8 5/8″ (8.5+1/8″)
    W-X: Across back plus 3/16” = 8 15/16″

    I do believe that all these measurements are right I even double checked the relationship to the across shoulder.
    (Across shoulder 18″ -1/2″) = (17.5/2) = 8 3/4″ + 3/16″) = 8 15/16″

    Basically these lines are almost on top of each other. How would I deal with shaping the arm hole as far as how much I can deviate from the across back measurement.

    Thanks for your reply in advance.

    Reply

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