Sizing inconsistency is one of the most common complaints in clothing brand production, and one of the most preventable. A customer orders a medium, receives it, washes it once, and finds it fits like a small.
They may not return the garment, but they will not order again. Understanding what pre-shrinking is and what it actually guarantees matters more than most founders realise when evaluating suppliers.
Why Cotton Fabrics Shrink
Cotton is a natural fibre. Unlike synthetic yarns, which are thermally stabilised during production, cotton fibres retain a degree of internal tension from the spinning and knitting process. When heat and moisture are introduced in a washing machine, the fibres relax and contract. The fabric pulls in toward its natural state.
The amount of shrinkage depends on the construction of the fabric, the yarn type, and how much tension was applied during the knitting process. A standard untreated cotton fabric can shrink anywhere from 3% to 8% in the first wash. For a t-shirt cut at 70 cm body length, a 6% shrink brings it to 65.8 cm, a loss that crosses over into the next size bracket.
What Pre-Shrinking Does
Pre-shrinking, or sanforizing, is a mechanical finishing process applied to the finished fabric before cutting and sewing.
The fabric is fed through a machine that applies controlled steam and compression in the warp direction (along the length of the fabric), then through a shrinkage reduction sequence. This forces the relaxation and contraction to happen in the factory, before the garment is sewn.
After pre-shrinking, the fabric is measured. A properly executed process will bring residual shrinkage down to 0 to 3%. A well-specced blank that leaves the factory pre-shrunk will arrive at its stable size. The medium will wash and remain a medium.
There is also a version of pre-shrinking that happens at the garment level: finished pieces are washed before shipping. This is less precise than fabric-level sanforizing but achieves a similar result. Some manufacturers use one, some the other, and some use both.
What It Does Not Do
Pre-shrinking is not a permanent treatment that makes fabric shrink-proof forever. It reduces the residual shrinkage to within a controlled tolerance. A well-pre-shrunk garment should change no more than 1 to 2% after subsequent washes, well within what a customer would notice as a change in fit.
It also does not compensate for poor pattern grading or inconsistent cut-and-sew. A garment can be pre-shrunk correctly and still fit inconsistently across a batch if the cutting tolerances are loose. Pre-shrinking solves the textile problem. Quality control in production solves the construction problem.
Why This Matters When Ordering Blanks
When you source blanks for your brand, you are buying garments that your customers will receive, wear, and wash. The sizing they experience on the first wear needs to match what they experience on the tenth. That is a function of pre-shrinking.
Not all blanks on the market are pre-shrunk to the same standard. Some suppliers declare a shrinkage tolerance of 5%, which sounds small until it translates to a medium that fits like a small after three washes.
When comparing options, ask specifically what the declared residual shrinkage is and how it is tested. A supplier who cannot answer that question with a specific number is not controlling for it.
René Bassett blanks, the 300 GSM t-shirts and 480 GSM hoodies, are pre-shrunk in-house as part of the finishing process. Shrinkage tolerance is maintained at 0 to 3% across batches, and measurements are tested for consistency before stock is released.
For a brand where repeat customers are part of the business model, and the economics of clothing brands require that they are, sizing reliability is not a secondary concern. It is one of the few things that is entirely within the supplier's control, which makes it a reasonable thing to hold them to.
Pre-Shrinking and Garment Dyeing
One related detail worth knowing: garment dyeing, by nature, functions as a pre-shrink step. When a finished garment is submerged in dye, it undergoes the same exposure to heat and moisture that a domestic wash produces. The shrinkage happens in the dye bath. Garments that go through the garment dyeing process arrive pre-shrunk as a direct result of that process.
This is also one reason the dyeing process requires blanks that are already properly constructed. Any instability in the fabric will be amplified when it relaxes in the bath. A blank with inconsistent knit tension or untreated shrinkage will come out of the dye bath at an unpredictable size. The quality of the blank determines the quality of the dyed piece.
Frequently Asked Questions
What does pre-shrunk mean on a clothing label?
It means the fabric or finished garment was treated before shipping to remove the majority of its natural shrinkage potential. Cotton fibres contract when exposed to heat and moisture. Pre-shrinking forces that contraction to happen in the factory, so the garment you receive is already at or close to its stable size.
Does pre-shrunk fabric still shrink?
Yes, slightly. Pre-shrinking reduces residual shrinkage to a controlled tolerance, typically 0 to 3%, but does not eliminate it entirely. A well-pre-shrunk garment may lose 1 to 2% of its dimensions after the first wash. That is generally not perceptible as a change in fit.
What is sanforizing?
Sanforizing is a specific mechanical pre-shrinking process applied to fabric before it is cut and sewn. The fabric passes through a machine that applies controlled steam and compression, forcing the fibres to relax and contract under controlled conditions. The Sanforized trademark was the original commercial standard for this process, and the term is now commonly used to describe fabric-level pre-shrinking in general.
How much does cotton shrink if it is not pre-shrunk?
An untreated cotton fabric can shrink between 3% and 8% in the first wash, depending on the yarn type, GSM, and knit structure. At the higher end of that range, a garment can effectively drop an entire size. This is the problem pre-shrinking exists to prevent.
Is pre-shrunk the same as preshrunk or pre shrunk?
All three refer to the same thing: a garment or fabric that has been treated to reduce residual shrinkage before sale. The hyphenated form is the most common in technical writing, but the meaning is identical across all three spellings.
Does pre-shrinking affect the hand feel of the fabric?
The mechanical process can slightly soften the fabric surface, but the change is minimal on a well-constructed blank. Garment-level pre-shrinking (washing the finished piece before shipping) tends to produce a slightly softer result than fabric-level sanforizing. Neither process meaningfully degrades the hand feel of a quality blank.
Why do some brands use cotton/poly blends instead of pre-shrinking?
Polyester fibres do not shrink the way cotton does, so adding polyester to a blend naturally reduces overall shrinkage without a separate pre-shrink step. This is a lower-cost approach to the same problem. The tradeoff is a different hand feel, reduced print quality on DTG, and the inability to garment dye consistently. Pre-shrinking achieves the same sizing stability while keeping the fabric at 100% cotton.
How do I know if a blank supplier pre-shrinks their garments?
Ask for the declared residual shrinkage tolerance and how it is measured. A supplier with a controlled process will give a specific figure, typically 0 to 3%. Vague answers, or tolerances above 4%, indicate the process is not being tightly controlled. You can also test it yourself by measuring a blank before and after two washes at 30°C.
Related Reading
What Is Pre-Shrunk Fabric? Why It Matters for Consistent Sizing Across Orders
Sizing inconsistency is one of the most common complaints in clothing brand production, and one of the most preventable. A customer orders a medium, receives it, washes it once, and finds it fits like a small.
They may not return the garment, but they will not order again. Understanding what pre-shrinking is and what it actually guarantees matters more than most founders realise when evaluating suppliers.
Why Cotton Fabrics Shrink
Cotton is a natural fibre. Unlike synthetic yarns, which are thermally stabilised during production, cotton fibres retain a degree of internal tension from the spinning and knitting process. When heat and moisture are introduced in a washing machine, the fibres relax and contract. The fabric pulls in toward its natural state.
The amount of shrinkage depends on the construction of the fabric, the yarn type, and how much tension was applied during the knitting process. A standard untreated cotton fabric can shrink anywhere from 3% to 8% in the first wash. For a t-shirt cut at 70 cm body length, a 6% shrink brings it to 65.8 cm, a loss that crosses over into the next size bracket.
What Pre-Shrinking Does
Pre-shrinking, or sanforizing, is a mechanical finishing process applied to the finished fabric before cutting and sewing.
The fabric is fed through a machine that applies controlled steam and compression in the warp direction (along the length of the fabric), then through a shrinkage reduction sequence. This forces the relaxation and contraction to happen in the factory, before the garment is sewn.
After pre-shrinking, the fabric is measured. A properly executed process will bring residual shrinkage down to 0 to 3%. A well-specced blank that leaves the factory pre-shrunk will arrive at its stable size. The medium will wash and remain a medium.
There is also a version of pre-shrinking that happens at the garment level: finished pieces are washed before shipping. This is less precise than fabric-level sanforizing but achieves a similar result. Some manufacturers use one, some the other, and some use both.
What It Does Not Do
Pre-shrinking is not a permanent treatment that makes fabric shrink-proof forever. It reduces the residual shrinkage to within a controlled tolerance. A well-pre-shrunk garment should change no more than 1 to 2% after subsequent washes, well within what a customer would notice as a change in fit.
It also does not compensate for poor pattern grading or inconsistent cut-and-sew. A garment can be pre-shrunk correctly and still fit inconsistently across a batch if the cutting tolerances are loose. Pre-shrinking solves the textile problem. Quality control in production solves the construction problem.
Why This Matters When Ordering Blanks
When you source blanks for your brand, you are buying garments that your customers will receive, wear, and wash. The sizing they experience on the first wear needs to match what they experience on the tenth. That is a function of pre-shrinking.
Not all blanks on the market are pre-shrunk to the same standard. Some suppliers declare a shrinkage tolerance of 5%, which sounds small until it translates to a medium that fits like a small after three washes.
When comparing options, ask specifically what the declared residual shrinkage is and how it is tested. A supplier who cannot answer that question with a specific number is not controlling for it.
René Bassett blanks, the 300 GSM t-shirts and 480 GSM hoodies, are pre-shrunk in-house as part of the finishing process. Shrinkage tolerance is maintained at 0 to 3% across batches, and measurements are tested for consistency before stock is released.
For a brand where repeat customers are part of the business model, and the economics of clothing brands require that they are, sizing reliability is not a secondary concern. It is one of the few things that is entirely within the supplier's control, which makes it a reasonable thing to hold them to.
Pre-Shrinking and Garment Dyeing
One related detail worth knowing: garment dyeing, by nature, functions as a pre-shrink step. When a finished garment is submerged in dye, it undergoes the same exposure to heat and moisture that a domestic wash produces. The shrinkage happens in the dye bath. Garments that go through the garment dyeing process arrive pre-shrunk as a direct result of that process.
This is also one reason the dyeing process requires blanks that are already properly constructed. Any instability in the fabric will be amplified when it relaxes in the bath. A blank with inconsistent knit tension or untreated shrinkage will come out of the dye bath at an unpredictable size. The quality of the blank determines the quality of the dyed piece.
Frequently Asked Questions
What does pre-shrunk mean on a clothing label?
It means the fabric or finished garment was treated before shipping to remove the majority of its natural shrinkage potential. Cotton fibres contract when exposed to heat and moisture. Pre-shrinking forces that contraction to happen in the factory, so the garment you receive is already at or close to its stable size.
Does pre-shrunk fabric still shrink?
Yes, slightly. Pre-shrinking reduces residual shrinkage to a controlled tolerance, typically 0 to 3%, but does not eliminate it entirely. A well-pre-shrunk garment may lose 1 to 2% of its dimensions after the first wash. That is generally not perceptible as a change in fit.
What is sanforizing?
Sanforizing is a specific mechanical pre-shrinking process applied to fabric before it is cut and sewn. The fabric passes through a machine that applies controlled steam and compression, forcing the fibres to relax and contract under controlled conditions. The Sanforized trademark was the original commercial standard for this process, and the term is now commonly used to describe fabric-level pre-shrinking in general.
How much does cotton shrink if it is not pre-shrunk?
An untreated cotton fabric can shrink between 3% and 8% in the first wash, depending on the yarn type, GSM, and knit structure. At the higher end of that range, a garment can effectively drop an entire size. This is the problem pre-shrinking exists to prevent.
Is pre-shrunk the same as preshrunk or pre shrunk?
All three refer to the same thing: a garment or fabric that has been treated to reduce residual shrinkage before sale. The hyphenated form is the most common in technical writing, but the meaning is identical across all three spellings.
Does pre-shrinking affect the hand feel of the fabric?
The mechanical process can slightly soften the fabric surface, but the change is minimal on a well-constructed blank. Garment-level pre-shrinking (washing the finished piece before shipping) tends to produce a slightly softer result than fabric-level sanforizing. Neither process meaningfully degrades the hand feel of a quality blank.
Why do some brands use cotton/poly blends instead of pre-shrinking?
Polyester fibres do not shrink the way cotton does, so adding polyester to a blend naturally reduces overall shrinkage without a separate pre-shrink step. This is a lower-cost approach to the same problem. The tradeoff is a different hand feel, reduced print quality on DTG, and the inability to garment dye consistently. Pre-shrinking achieves the same sizing stability while keeping the fabric at 100% cotton.
How do I know if a blank supplier pre-shrinks their garments?
Ask for the declared residual shrinkage tolerance and how it is measured. A supplier with a controlled process will give a specific figure, typically 0 to 3%. Vague answers, or tolerances above 4%, indicate the process is not being tightly controlled. You can also test it yourself by measuring a blank before and after two washes at 30°C.
Related Reading
What Does GSM Mean in Clothing? And Why It Matters More Than You Think
Ring-Spun vs Open-End Cotton: What the Difference Means for Your Brand
What Is French Terry? The Complete Fabric Guide for Clothing Brands
Written by
Ricardo Vieira
Ricardo Vieira is the founder of René Bassett and has worked in the Portuguese textile industry for over 10 years. He grew up close to garment production — his family's company operated in the sector — and developed a technical understanding of fabrics, fabric weights and customisation processes that shapes every product René Bassett brings to market. He writes about everything a clothing brand founder needs to understand about blanks, fabrics and production before launching — or scaling — a brand.