Seam Allowances – How to Cut Them Properly?

Last Updated on October 13, 2022

What is Seam Allowances – How to Cut Seam Allowances Properly? When making products of complex shapes, sometimes difficulties arise after eversion: seams bristle, lines, and bends lie unevenly. To avoid such problems, you need to carve allowances properly.

Collars, pocket flaps, necklines, and armholes – all these figured parts of the product and all kinds of fabric crafts (toys, pillows, covers, etc. ), are not so difficult to sew. Remember to trim the allowances before handing in the final product or part. Then the seams will not wrinkle, and the fabric will bulge.

What Are Seam Allowances, and Why Use Seam Allowances?

Seam allowances are the amount added to the pattern details along all contours for assembling and processing the seams of the product.

 All products are interconnected in one way or another. Depending on the chosen method of connection, the type of fabric, and the type of technological operation, the seam allowances will be different. First, you need to decide what is called a seam allowance.

Seam Allowances

The seam allowance is the space left between the edge of the cuts and the stitching used to join them.

You should note that products sewn at the factory – mass production, and in the atelier – individual tailoring, will have different seam allowances.

With the factory sewing method, the cut goes directly to the sewing conveyor, the cuts are practically not subject to shedding, and the product is strictly designed for a standard figure according to a typical size table, so there is a minimum allowance. The machines used in the factory perform two operations simultaneously: grind parts and overcast them in one go.

A product made in an atelier or at home for a specific figure provides for fitting. At the fitting, the product may have to be “released” at the seams, so you need an additional fabric supply. 

In addition, during the fitting, the sections additionally crumble. If the fabric is sliding, then they crumble very much. After making changes, the product is tried on again. And only after that do they grind it at the seams and overcast the sections. Here universal machines and overlocks are used separately.

Types of Seam Allowances

A fundamental question remains what types of seam allowances are there and how to determine the correct width of allowances for a particular product?

Seam Allowances

Allowances are divided into:

  • Allowances for seams and hem. The nature of the product and the quality of the fabric used in its construction determine the price.
  • Allowances are made to fit the product according to the figure. Such allowances are used for individual tailoring of products. The sections for which additional allowances are added are determined by the master, taking into account the features of the customer’s figure. In case of errors in the design, with the help of such allowances, you can correct flaws. The size of the allowances is determined directly by the master when grinding parts on the material.

IMPORTANT! The standard width of the seam allowances in most cases is 1.5 cm. This width is very convenient because the process of basting and trying on the edges of the allowances can be slightly frayed, and this width allows you to cut the frayed threads with an overlock knife. At the same time, the allowances are reduced somewhat but remain convenient for ironing and fixing.

  • For knitwear, the seam allowance can be from 0.7 cm to 1.5 cm (depending on the material’s properties and the method of sewing the product). Allowances for the bottom of the jersey and sleeves are standard 3-4 cm.
  • For loose, bulky, or thick materials, the seam allowance should be increased and cut off during the sewing process.
  • Excess allowances in individual sections and nodes of the product (collars, edges of the sides, lapels, etc.) are also cut to the required width during processing.
  • Allowances along the bottom line of products can be from 1.5 cm (for skirts such as the sun, skirts, and tops made of transparent materials, etc.) up to 6 cm (for outerwear made of thick heavy fabrics).
  • The standard width of the allowances on the bottom of the sleeves varies depending on the sleeve style. For a sleeve without a cuff, the allowance is 4 cm.

When cutting sleeves with cuffs, allowances from 1 to 1.5 cm are added along the bottom of the sleeves (the standard width is 1.5 cm). Similar width of allowances is added along the contours of the cuff.

Size of Allowances

It is better to measure and recheck yourself seven times when building a pattern than to make too large allowances.

Seam Allowances
Credit: Wikipedia

The amount of allowances depends on several reasons:

  • Firstly – from the part section (side seam, shoulder, armhole, bottom of the product). Different parts of the product are provided with varying amounts of allowance.
  • Secondly, it depends on the type and properties of the fabric (thin, thick, easily crumbling, stretched). For example, allowances are increased when cutting products from easily crumbling fabrics. When cutting thick winter types of fabric, the size of the allowances is also increased.
  • Thirdly, on the type and intent of the seam.

There are tables of recommended seam allowances for various types of products. I suggest you familiarize yourself with the allowances for dresses, skirts, and trousers.

What to Consider When Cutting Allowances?

Seam Allowances

What to consider when cutting and at what inputs should the allowances be increased:

  • If the fabric crumbles or has a separation in the seams, then the size of the allowances must be increased by 1.5-2 times;
  • If you use a type of seam that implies large allowances (the same stitching);
  • If the fabric is thicker and denser than recommended in the pattern;
  • If the figure is different from the typical one or you are sewing a product without a layout and trying it on will be carried out. Here you need to increase the allowances by 1.5-3 times because a margin of 1 cm does not imply changes to the design.
  • Too large allowances are also not very good because they can interfere with the fitting. So, an extra 2 cm along the sleeve and armhole will tighten the seam, dig into the armpit, and not allow you to see the fit with the neck. Do not forget to reduce the allowances after trying on because they will interfere with assembly.

If you cut the product with the allowances laid down in the patterns, then at the fitting, you can make adjustments only downwards due to the allowance for the freedom of fit taken into account.

How to Cut Seam Allowances

Seam Allowances

It would be best if you cut allowances according to the rules.

Step 1

Before turning the product inside out, trim the seam allowances close to the stitching, leaving no more than 5 mm. Leave only allowances along the turning hole uncut!

Step 2

Be sure to cut the seam cuts in the corners to 0.2 – 0.3 mm.

Step 3

On curved or rounded lines, score slightly at an angle to (or perpendicular to) the seam line. If the bend is very strong, then on the allowance, instead of the usual notch, cut out small triangles. Notches should not reach the line by 2-3 mm.

Step 4

If the fabric crumbles heavily, glue the parts with a thin adhesive cloth before sewing the parts so that the stitching does not spread later.

Tools for Marking and Cutting Allowances

There is a wide range of tools for transferring pattern details to the material and marking allowances. The most commonly used by craftsmen in their work are:

Wax Pencil

Leaves smooth, smooth lines and periodically need to be sharpened. Self-disappearing marker It is more convenient to use a self-disappearing marker to transfer pattern outlines to thin fabrics.

Cutting Allowances

Over time, the lines disappear and leave no trace. Water helps to speed up the process – moisten the area with a small amount of water or rinse the product in water – traces of the marker will completely disappear instantly.

Simple Pencil

Cutting Allowances

 With a simple pencil, it is convenient to transfer the contours of magazine patterns to tracing paper and mark the contours of parts on rigid cushioning materials.

Tailor’s Chalk

Cutting Allowances

They are also used to transfer pattern outlines to the fabric. Before tracing the pattern outlines, sharpen both edges of the chalk at a slight angle with a knife or scissors. The lines will be thin and clear.

Tailor’s Patterns

On many tailor’s patterns, made of transparent plastic, along the curved edges with thin lines that repeat the shape of the edge, seam allowances 0.6 cm – 1.2 cm – 1.5 cm wide are marked.

Cutting Allowances

With their help, you can draw neat allowances of the required width when cutting parts. It is a convenient option, especially for beginners in sewing.

Metric Ruler 

 Using the Madeira metric ruler, you can not only accurately mark allowances of different widths but also folds loops and buttonholes. The ruler is made of plastic and is very easy to use.

Cutting Allowances

It is also very convenient to draw circles with such a metric ruler. With the help of a ruler, you can design a “sun” skirt directly on the fabric. 

Fix the ruler through the hole in the corner of the material. (use an ordinary awl for this) Use carefully to draw an arc of a given radius with a disappearing marker. Allowances are marked similarly but with an arc of a smaller radius.

What Seam Allowances to Add When Cutting the Product

When working with patterns, beginner craftswomen often have a question: is it always necessary to add seam allowances when cutting products, and what width should the correct allowances be? In this lesson, we decided to focus on these crucial issues and consider the topic of seam allowances in detail.

How Do Allowances Differ From Allowances?

Sometimes craftswomen, especially beginners, confuse increases and allowances. However, these are completely different concepts. Increases in freedom of fitting allow you to achieve the necessary degree of fit of clothing to the body and are laid by the master at the stage of designing basic patterns. 

The increments can vary and are determined by the fashion designer depending on the product’s style, fabric type, and other parameters.


Stick to the golden mean in the choice of allowances. The more you cut and sew the more confidence you will have in the cutting technique you are working with. And the less often you will add extra centimeters of allowances “just in case.”

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