A Basic Guide on Pattern Alterations for Beginners

Fitting is an important part that makes a garment perfect. The art of garment fitting requires skill and patience. When standard fit is done, garments will look better and feel more comfortable. Making apparel which really fits is one of garment making’s greatest challenges and crucial successes. No matter how lovely the fabric, how fine the garment design, or how expert the sewing, the results are disappointing if the garment fits poorly. Perfect measurements are the key of good fit.

Good fit are influenced by many things such as:

  • The current fashion look,
  • The hang and stretch of the fabric,
  • The amount of ease preferred and
  • Figure size and type.

Pattern Alteration:
Pattern alteration means customize patterns to fit according to body shape. For example, shortening arms or lengthening a top. Patterns are prepared according to standard measurement chart which are based on average sizes. After measuring the human body and adding needed ease, compare this measurement to the pattern’s measurement.

All commercial patterns are made to standard average body measurements for each figure type or size. Companies spend a lot of time and money inviting the public to take part in measurement surveys, eager for their patterns to fit as many people as possible. In reality, of course, we are all different – but standardizing measurements is a necessary process for the industry.

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Of course, if your measurements are correct, you are ready for the next step. If not, you will need to customize your pattern to create a more personalized fit – and choosing the correct size will help enormously. It is best to purchase the size that most closely fits your bust and hip measurements. This is because, as a general rule, size alterations are easier to make in other areas. Creating and altering patterns is a vast subject area with varying degrees of simple and complex methods involved.

Pattern Alteration
Fig: Pattern adjustment or alteration

Pattern adjustment or alteration is often necessary to achieve good fit in a garment. Once the fabric is cut, however, fitting adjustments are limited to existing darts and seam allowances. Before cutting the garment, check the pattern fit and alterations according to the correct body measurement that will eliminate many problems form fabric. Therefore, fitting problems should be solved before the garment is cut by making needed changes in the pattern.

In pattern alteration, sustain the pattern outline wherever possible. To get the best result, using slash and spread or fold method and the result is a permanently altered pattern that can be used over and over again.

A pattern can be altered and adjusted three ways:

  1. By folding out excess fullness to make an area smaller.
  2. By slashing and spreading to increase dimensions, or slashing and overlapping to decrease dimensions.
  3. By redrawing darts or seamlines.

Importance of Pattern Alterations:

  1. To get a perfect fit on your figure, garment is cut after the pattern is altered.
  2. If the pattern is altered before the fabric is cut, there will be no adjusting in the final fitting.
  3. There is no danger of wasting expensive fabric and spoiling the garment.
  4. Each adjustment necessary in the flat pattern for saving time and avoid ripping later.
  5. Sometimes alterations are essential to get perfect pattern.

Keep the records of pattern alterations and their effectiveness; it is the way to perfect individual requirements.

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Patterns Alteration Standards:

  1. Original grain-lines are saved.
  2. Patterns are kept in balance and proportion.
  3. Change is created only where needed and is not obvious.
  4. Designer’s lines are protected.

Basic Rules or Techniques of Pattern Alteration:
Traditionally, alteration of garment patterns is an essential step in producing attractive and accurately fitting clothing from patterns which already exist. There have been numerous publications by tailoring experts on how to alter garment patterns for different figure forms. Alterations can be done by using measurements, taken by a tape measure and incorporating them onto a paper pattern using the slash, seam or pivot methods.

Basic pattern alteration techniques are given below:

  1. All similar pieces must be altered to correspond with the alterations on the major piece.
  2. Additions or extensions must be made by taping an extension strip to the edge involved.
  3. Altered patterns must have the same character as the original pattern piece.
  4. Correct movement on altered pattern to give the altered line the same character as the original line.
  5. The altered pattern must be properly flat, as like the original pattern piece.

There are also some methods for pattern alteration:

  • Pattern alteration for flattering the figure
  • Pattern alteration for non-standard figures
  • Pattern alteration with experimental methods
  • Pattern alteration using computer-aided design (CAD) programs

Principles of Pattern Alteration:

1. A far as possible make changes within the pattern by slashing and spreading or slashing and lapping. Patterns can also be altered by redrawing the edges of the pattern. (This is the method adopted for altering garments at the time of fitting.) But the first method is by far the best in altering paper patterns.

2. To preserve the original grain line, make all slashes and folds parallel or perpendicular to the grain line (to center front line, center back line etc.).

3. Where there are darts, make changes between the tip of the dart and the outside edge.

4. If an alteration in length is made along one edge of the pattern, take care to make an identical alteration in the adjoining edge. For example, if back shoulder seam is shortened the front shoulder seam should also be shortened.

5. When tucks or darts are used for making a pattern smaller, remember that the width of these should be just half the amount to be removed.

6. When decreasing or increasing the width of pattern pieces, if only half the pattern (half back or half front) is used, subtract or add only one fourth of the total adjustment to be made. For example, if waist measurement has to be increased by one inch, add ¼” to the half back pattern and the same amount to the front pattern. If only a front or back section needs adjustment, add or minus half the amount of the adjustment to the respective section.

7. When the pattern alteration involves slashing and spreading, it is necessary to keep a sheet of paper beneath and to pin or stick to it the spread-out parts so that they will thereafter remain in position. On spreading or lapping after slashing, some edges of the pattern become jagged. These must be trimmed after drawing the new seam lines.

Pattern Alterations for Basic Fit Problems:
Most of common fitting problems are increase or decrease in height and width. Alterations help to increase the life of the garment.

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How to Check the Altered Fit?
Before cut the fashion fabric check the pattern fit, only the basic parts of the garment together. Take a helping person who helps you to check the fit of the garment. Otherwise you stand in front of a full-length mirror. Use the following checklist that helps you, if further alterations or minor fitting is needed for a good fit.

  1. Adequate wearing ease is available for sitting, mov­ing and bending.
  2. Armhole seams curve smoothly over the end of shoul­der.
  3. Crosswise grain lines are parallel to floor.
  4. Crotch depth is right, neither too low and baggy nor too tight and binding.
  5. Darts point to the fullest part of the curve.
  6. Hemline is even.
  7. Hipline fits smoothly.
  8. Lengthwise grain lines, side seams, center front and center back seams hang straight or at right angles to the floor.
  9. Pant legs hang smoothly and do not restrict any part of the legs.
  10. Pants hang smoothly from the waist. The waistband fits the body comfortably and stays in place when bending and sitting.
  11. Pants have no pulls or excess fabric across the front or back crotch level.
  12. Shoulder seam length comes to end of shoulders.
  13. Sleeves are comfortable with no wrinkles.
  14. The length of the garment is becoming.

Body contour, posture, body proportion and symmetry affect the fit of clothing. Patterns are designed for an average symmetrical body shape, with standard posture and body proportions. Very few individuals are the same size and shape as this standard model; therefore, pattern alterations need to be made before garment pieces are cut and fitting adjustments are also made during the assembly process.


  1. Clothing Appearance and Fit: Science and Technology by J. Fan, W. Yu and L. Hunter
  2. How to Use, Adapt, and Design Sewing Patterns by Lee Hollahan
  3. Dressmaking: The Complete Step by Step Guide to Making Your Own Clothes by Alison Smith
  4. http://oaktrust.library.tamu.edu/bitstream/handle/1969.1/87404/pdf_2272.pdf
  5. https://archive.org/stream/std12voctddem2006tnbooks/std12voctddem2006tnbooks_djvu.txt
  6. http://fashionelongation.com/importance-principles-pattern-alteration/

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  7. What is Pattern Engineering | Components of Pattern Engineering
  8. Grading and Pattern Making: Job Interview Questions
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