Sewing Tips

Sloper, Block, or Pattern?

What is the difference between a Sloper, a Block,  and a Pattern?


You may have heard any of the following terms: “pattern sloper”, “sloper pattern”, “pattern block”,  “block pattern”, “sewing block” ,“sewing pattern block”….and wondered “What’s the difference?”    Wikipedia explains the difference by stating that slopers are for home sewing and blocks are for industry (  I would restate that by explaining that slopers are useful for one-offs, while blocks are better for repeat sewing. More on that later.

I can understand why these terms get used together….and confused.  “Block” is a common word, and you want to let people know you’re talking about sewing, not a child’s building toy…but not a sewing patchwork “block” either. “Sloper” is an un-common word in general language.  A “pattern” could be any design that you copy. So the terminology can get twisted around in the sewing world, and what people are trying to clarify just gets more mixed up. You can cut through the confusion by understanding this:

A basic fitted SLOPER

is used to make multiple silhouette BLOCKS,

which are used to create endless design PATTERNS.

(Please note: I am only familiar with U.S. terminology; it may very well differ in other English-speaking countries.  For example designer Thomas Pink in London offers  “free basic sewing blocks” online, which would be considered “slopers” in the U.S. (:  Noted British patternmaker and author Winifred Aldrich uses “block” for what we in the U.S. call “sloper” in her “Metric Pattern Cutting” series ( ) So very likely this is equivalent to American “French  fries” = British “chips”,  American “potato chips” = British “crisps”, etc.  If that’s the case, then apologies to my family in Europe, South Africa, and Australia for this very American blog post!)

So in the U.S., what are Slopers, Blocks, and Patterns?

SLOPER: this is a paper representation of the human  body,  essentially a “body double” or “second skin”.   Adele Margolis, in her book  Make Your Own Dress Patterns, describes a sloper this way:  ” It is used as the basis for creating new designs..It has no fullness, design details, or seam allowances.”  The sloper can be made by draping muslin fabric on a dressform and pinning into shape, or by drafting onto paper (or computer) from body measurements. A  sloper has no “ease” or wiggle-room. It’s not yet a pattern, it’s a tool you can use as the first step towards making a block, which is used to make the pattern.

There are 6 basic slopers: front  and back bodice,  front and back skirt, sleeve, and pant:.


(from”Designing Apparel Through the Flat Pattern”, Fairchild Publishing

The bodice slopers are used to make blocks for  shirts, blouses, jackets, coats .  Bodice slopers together with skirt slopers are used to make dress blocks. Bodice slopers together with pant slopers are used to make jumpsuit blocks. Larger apparel manufacturers  make blocks starting from  slopers based on the measurements of dressforms that are specifically made for their firm ( the dressforms are sometimes named for the company’s favorite fit model). Smaller companies use ready-made dressforms.

If you are having a couture one-of-a-kind outfit made, the design assistant will begin by making you a personal sloper.  Likewise if you are making an outfit for a customer, you would start with taking their measurements to create their sloper.  If you sew occasionally for yourself, it is helpful to have a personal sloper. Drafting a sloper is fairly straightforward. There are plenty of sloper-drafting websites and videos online to help you with this. Your library may have sloper drafting textbooks books that you can borrow; I recommend “How to Draft Basic Patterns” and “Patternmaking for Fashion Design”


Services such as  StringCodes ( )  and Kosher Patterns ( ) will create a personal sloper for you based on measurements you supply.

In design school, pattern manipulation (learning how to create fashion silhouettes) is generally done using slopers , without seam allowance, because it’s easier to illustrate the design process this way.  Adding the minimal wearing ease to turn it into a second-skin fitting shell is not difficult because there are fairly standard guidelines:



BLOCK: this is a basic garment design made by using the sloper and adding  seam allowance, plus wearing ease needed for comfort, plus the design ease needed for the particular silhouette.

Ease is the difference between body measurements and garment measurements

Wearing ease (also called Fitting Ease) is the measurement of fabric in a garment needed for body movement: breathing, walking, bending, stretching, etc.  There are degrees of wearing ease, depending on  the fullness/fit/volume desired: whether the patternmaker is aiming for a garment to be close-fitting, semi-fitted, loose-fitting, or extra-loose fitting.

Design ease is the additional measurement of fabric added to a garment above and beyond the wearing ease to create a certain silhouette/shape/style: pencil skirt versus A-line skirt, set-in fitted sleeve versus puffed sleeve, boot-leg pant versus flared.

Manufacturers develop blocks for all of their garment silhouettes, and use them as “shorthand” in the design process, to simplify communication between the Designer, the Technical Designer , and the Patternmaker. If you’ve ever shopped from mail-order catalogs for apparel basics, you’ve probably noticed pages like these, that explain a manufacturer’s different blocks:


Establishing a manufacturer’s block takes dozens of fittings and tweaks.  Adding a new block to an apparel assortment is a big undertaking.  Apparel production guru Kathleen Fasanella  calls a block a “parent pattern” , from which multiple offspring designs may be born:  Manufacturers  use those same blocks season after  season,  changing the fabric plus possibly the pockets or trims, etc., to design a new style that still fits the same. Chances are that if you are hired as a designer, tech designer, or patternmaker by an established manufacturing firm, you might never see a sloper; they may be well into blocks already.

It’s important to understand that a block is not the same as a sloper. If you Google “garment pattern block“unfortunately you’ll get mostly slopers:


There are countless websites titled “how to draft a block” however  what they are really explaining is “how to draft a sloper”.  Or possibly how to take a sloper and add seam allowance and hem allowance, and minimal wearing ease  to make a  fitting shell.  Yet a fitting shell is still not a block.

I have yet to find a website that tells you how to go from sloper to block, probably because there is no  formula for  adding the additional wearing ease  necessary for the volume and fit desired, plus design ease for a specific silhouette or style. Blocks are completely subjective to personal taste.  What one person calls “fitted”, another might feel is too constricting.  How much “hook” a pants crotch block has is different from designer to designer, which is why certain jeans might fit you perfectly, and other brands not at all.

Learning how to make well-fitting blocks is an art form. Developing blocks takes trial-and-error, and is learned more commonly on the job, in the apparel industry, than in design school or Home Economics class.  So in that sense, Wikipedia is right: the home sewer making a single garment probably goes  straight from drafting a personal sloper, to manipulating that sloper for silhouette and design ease, then adding wearing ease to create a usable sewing pattern.  Similarly, if you order a custom-made couture dress, the design assistant will measure you for your personal sloper, develop the fashion design from there, and then add the wearing ease. This makes sense for sewing single items.

Compare that to bulk manufacturing: the  pattern-maker takes  the fitted sloper, adds seam allowance plus wearing ease (volume) plus design ease (shape) to create standard silhouette blocks, and from there manipulates the design to create the seasonal sewing patterns. Reason for the difference?  The mass manufacturer is planning on using the blocks over and over again, whereas in couture (or in home-sewing) you are generally getting that dress made for you one time.

And once the manufacturer has developed a block library, the initial slopers aren’t much needed.  New variations of blocks are tweaked from successful existing blocks.  No need to reinvent the wheel!

But there is nothing keeping the independent sewer from making her own blocks, and it is immensely helpful to have them:

  1.  for use as basic sewing patterns
  2.  as a “master pattern” or “working pattern”, for development into fresh patterns
  3.  to check against the measurements of commercial patterns quickly

If you sew from home, whether you are interested in making your wardrobe, or sewing for a small business, you should have more than slopers: you should have a collection of blocks.


PATTERN: (also called a  “production pattern”) this is a paper design ready to be duplicated in fabric for sewing. It is drafted from the block and adjusted for fashion design, such as adding collars or pockets, changing necklines or sleeve details, etc.  In industry, it is  tested by sewing up a muslin, fitted on the house fit-model (because the dressform can’t tell you how the sample feels, and can’t move anyway). It gets  pinned and marked and sent back to the pattern-maker for adjustments.  This process is repeated until the fit is approved in muslin, then the corrected pattern is used to remake the sample in the actual fashion fabric.

When that sample is fit-approved, the  final pattern is “trued” or corrected for smooth lines where darts are closed and connecting pieces stitched together,  the grain-lines are  checked for correct placement, notches are checked for correct joining of seams, then the entire pattern is graded up and down for the size range indicated. After all that, each graded size pattern is printed out and the pattern pieces that will be stitched together are “walked” to make sure they line up in length, to ensure smooth factory performance.  Just as in home-sewing, a great pattern is a joy to work with, while an error-filled pattern will slow you down and be frustrating to use.


Next Post: more about Blocks and how to use them.

Happy Sewing!


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