DU 305: How to Alter Raw Denim
Summary
Denim alterations are their own discipline — more demanding than standard tailoring, more dependent on specialist equipment, and governed by one overriding principle: it is almost always easier to make a large garment smaller than a small garment larger. When in doubt, err bigger. The waist is best taken in at the center back seam, not the side seams. Rise should almost never be altered. On selvedge denim, leg narrowing should go through the inseam to preserve the selvedge edge. A well-timed alteration extends the life of a pair of jeans by years — and is always better done sooner, before fades establish.
Q&A
Why should the waist be taken in at the center back seam rather than the side seams?
Gapping at the center back means the waistband is too large at that specific point. Taking in the side seams moves the back pockets closer together — changing the visual proportions of the rear panel without addressing the problem at its source. Taking in the center back seam addresses the issue directly, preserving pocket placement and rear panel proportions while removing the excess exactly where it exists. The center back is sewn on a flat felling machine, so the alteration requires specialist equipment to fully replicate the original seam character.
Can the rise be altered on a pair of raw denim jeans?
Almost never, and this is why getting the rise right at purchase matters so much. The front rise cannot be raised without changing the total height of the waistband — there is no additional fabric above it. It can be lowered, but fly construction makes this genuinely complex. The back rise can be reduced by working at the yoke junction, or theoretically raised by replacing the yoke entirely — but this requires access to matching original fabric and involves disassembling much of the top block. The labor is substantial, the result is rarely perfect, and the cost reflects both. Rise is the one dimension that cannot be meaningfully corrected after the fact.
Why should leg narrowing on selvedge denim go through the inseam rather than the outseam?
On selvedge jeans, the self-finished edge of the fabric runs along the outseam. When jeans are cuffed, this edge is visible — and the train track fade that develops along it over years of wear is one of the distinctive pleasures of owning selvedge denim. Any alteration to the outseam disrupts that edge and potentially that fade. Narrowing through the inseam preserves the selvedge edge exactly as it was, though it requires a specialist machine and the knowledge to sew through the cylinder of a completed leg opening.
How much can a waist be let out?
Approximately 1 inch maximum — sometimes 1.5 inches on selvedge denim where seam allowances tend to be more generous. Most jeans have approximately ¼ inch of seam allowance per panel at the side seams. Four panels at a side seam means approximately 1 inch of total let-out. Beyond that, additional fabric is required, which typically can't be sourced to match faded denim. This is why erring on the side of larger when buying is always the right call — taking in is far more tractable than letting out.
What is the difference between an original hem and a standard hem on altered jeans?
An original hem preserves the chain stitch roping effect of the factory hem — the characteristic puckering that develops over years of wear. This requires a chain stitch machine (Union Special or equivalent) and specific skill. A standard hem is sewn on a lockstitch machine, which produces a clean, functional result but without the roping character. The difference is visible to anyone who knows what they're looking at. For raw denim enthusiasts, it's worth requesting an original chain stitch hem specifically and confirming the tailor has the machine to do it.
Test Your Knowledge
Click each answer to reveal whether it's correct.
1. Where should a waist be taken in on a pair of jeans, and why?
A. At the side seams — they are the most accessible and easiest to open
❌ Incorrect. While side seams are accessible, taking in the waist there moves the back pockets closer together and changes rear panel proportions without addressing the gapping at its actual source.
B. At the center back seam — it addresses gapping at its source while preserving pocket placement and rear panel proportions
✓ Correct. Gapping at the center back means the waistband is too large at that specific point. Taking in the center back seam addresses it directly, preserving pocket placement and rear panel proportions. It requires a flat felling machine to replicate the original seam character — which is why most general tailors produce a different-looking result than a specialist denim alteration shop.
C. At the waistband itself — by removing and re-sewing the waistband at a smaller circumference
❌ Incorrect. Removing and re-sewing the entire waistband is a much more invasive approach than necessary. Taking in the center back seam and, if needed, the side seams addresses the problem with less disruption to the garment.
D. At the yoke seam — to preserve the shape of the rear panel
❌ Incorrect. The yoke seam is relevant for rise adjustments, not waist taking-in. The correct location for a waist alteration is the center back seam.
2. How much can a pair of jeans typically be let out at the waist?
A. Up to 3 inches — by opening the center back and both side seams
❌ Incorrect. 3 inches is the approximate range for taking in, not letting out. Letting out is constrained by seam allowance — approximately 1 inch total, sometimes 1.5 inches on selvedge denim.
B. Approximately 1 inch — sometimes 1.5 inches on selvedge denim — constrained by the available seam allowance
✓ Correct. Most jeans have approximately ¼ inch of seam allowance per panel at the side seams. Four panels at a side seam means approximately 1 inch of total let-out — sometimes 1.5 inches on selvedge where allowances tend to be more generous. Beyond that, additional fabric is required, which typically cannot be sourced to match faded denim.
C. Up to 2 inches — by letting out both side seams fully
❌ Incorrect. 2 inches would require more seam allowance than most jeans carry. The practical limit without adding new fabric is approximately 1 inch, or 1.5 inches on selvedge denim.
D. There is no limit — any size can be let out with enough effort
❌ Incorrect. The limit is real and hard — it is set by how much seam allowance the garment carries. Without additional fabric that matches the faded denim, meaningful let-out beyond 1–1.5 inches is not possible.
3. Why should leg narrowing on selvedge denim go through the inseam rather than the outseam?
A. The outseam carries more seam allowance and narrowing it would remove too much fabric
❌ Incorrect. Seam allowance distribution isn't the reason. On selvedge denim the outseam carries the self-finished edge of the fabric — altering it disrupts the selvedge and the train track fade that develops along it.
B. To preserve the selvedge edge and the train track fade that develops along it when jeans are cuffed
✓ Correct. The self-finished edge of selvedge fabric runs along the outseam. When jeans are cuffed, this edge is visible — and the train track fade that develops along it over years of wear is one of the distinctive pleasures of selvedge denim. Any alteration to the outseam disrupts that edge and that fade. Narrowing through the inseam preserves it completely.
C. The outseam construction is too complex to alter on a flat felling machine
❌ Incorrect. The reason is about preserving the selvedge edge and its associated fade, not about construction complexity. If you don't plan to cuff your jeans, an outseam adjustment is simpler and the selvedge concern is less critical.
D. The inseam is always easier to access than the outseam on finished jeans
❌ Incorrect. Narrowing through the inseam on a finished pair of jeans actually requires sewing through the cylinder of a completed leg opening — a specialty operation that most general tailors cannot do well. The reason to use the inseam is to preserve the selvedge edge, not for ease of access.
4. Why is rise the one alteration that should almost never be attempted?
A. It affects the fit of the waist and hip simultaneously, making proportional adjustment impossible
❌ Incorrect. Rise and waist/hip are related but the issue with altering rise isn't about proportional cascading — it's about the structural complexity and fabric constraints of the alteration itself.
B. The front rise cannot be raised without changing the total waistband height; the back rise requires disassembling much of the top block and access to matching original fabric
✓ Correct. The front rise cannot be raised because there is no additional fabric above the waistband. The back rise can theoretically be raised by replacing the yoke, but this requires matching original fabric and disassembling much of the top block — belt loops, yoke seam, waistband — each presenting serious obstacles. The labor is substantial, the result rarely perfect, and the cost reflects both. This is why rise must be gotten right at purchase.
C. The flat felling machine required for rise alterations is too expensive for most tailors to own
❌ Incorrect. Equipment cost isn't the reason. The problem with rise alterations is structural and material — there is simply no extra fabric to raise the front rise, and raising the back rise requires a complete top block disassembly with matching original fabric.
D. Rise alterations permanently change the fit of the waist and hip
❌ Incorrect. Rise alterations don't necessarily change the waist or hip — they are separate dimensions. The reason rise shouldn't be altered is about structural complexity and the absence of additional fabric to work with.
← Previous: DU 304 | ↑ Denim University | Next: DU 306 →
By Eric Steffen
Founder / Maker
FITTED Underground
When I started FITTED Underground, I partnered with a good friend — a Brooklyn based seamstress — who was excellent. She was genuinely skilled, with years of experience on a range of garments. But three months into our project, it became clear that she didn't want to learn the 10 machines or so required to build a proper pair of jeans. Not because she lacked ability, but because denim is its own discipline; its own mountain to climb. The flat felling machine. The chain stitch hemmer. The waistband machine with the folder and the roller. The specific seam sequences and construction logic of a five-pocket jean. These aren't extensions of standard tailoring knowledge — they're a largely separate craft that takes real time and real commitment to learn.
Denim alterations are no different. Most tailors can make some version of the adjustments described in this article using a single-needle lockstitch and a serger — the standard equipment of a competent tailoring shop. But the results vary significantly depending on whether the person doing the work understands denim construction specifically. And some alterations — particularly on the center back seam and the hem — require machines that most tailors simply don't have.
Denim is its own discipline — its own mountain to climb. The same is true of denim alterations. The right equipment matters almost as much as the skill.
This article covers what can be altered, what can't, and what to look for when you're choosing someone to do the work. It follows the same eight measurements we use for fittings at FITTED Underground, organized from the top block down through the leg taper.
Before any specific alteration, one governing principle:
It is almost always easier to make a large garment smaller than a small garment larger.
Removing fabric is a technical challenge. Adding fabric requires either seam allowance (which most jeans have very little of) or original fabric (which most people don't have). This is why we consistently advise clients who are debating between sizes to err on the side of larger rather than smaller, longer rather than shorter. The correction is almost always more tractable in that direction.
1. What Separates a Good Denim Alteration From a Great One
Three things determine the quality of a denim alteration: equipment, knowledge, and access to original fabric.
Equipment. The center back seam on a pair of jeans — the seam that runs from the waistband down through the seat — is sewn on a flat felling machine. This is a specialty machine with a specialty folder that produces a specific, very flat, very strong seam. It is not the same as a regular lockstitch seam. When this seam needs to be altered, doing it correctly requires either a flat felling machine or a very skilled hand on a standard machine who understands how to approximate the result. Most tailors don't have one. We do, which is one reason our waist alterations produce better results than most.
Similarly, the hem on a quality raw denim jean is sewn on a chain stitch machine — a Union Special or equivalent. The chain stitch produces the characteristic roping and puckering that develops over years of wear. When a hem is let down and re-stitched on a standard lockstitch machine, that roping effect is gone. The hem looks different from every other hem detail on the garment. For people who care about these things — and if you're reading this curriculum, you probably do — preserving the original hem character is worth asking for specifically, and worth paying more for.
Knowledge. A tailor who understands denim construction approaches an alteration differently than one who doesn't. They know which seams were sewn in which sequence, which seams can be opened without compromising structural integrity, and how fading will affect the visibility of any new seam. Denim fades. A new seam sewn through fabric that has been worn for two years will be more visible than the original construction — this is unavoidable, but a skilled denim tailor knows how to minimize the visual disruption.
Access to original fabric. Several alterations — particularly lengthening the inseam or raising the rise — require additional fabric. If you're having a garment altered by the brand that made it, and they have remnants from your order, this is possible. If you're taking a pair of jeans to a third-party tailor, the fabric they add will likely not match. This isn't always a dealbreaker — an alteration at the inseam, hidden when the jeans are worn, is less visible than one at the outseam — but it's a real constraint worth understanding before you commit to an approach.
For alterations to FITTED Underground jeans, and for alterations to other brands where we can help, visit our alteration services page for details.
2. What Can and Can't Be Altered
The construction of a pair of jeans — flat-felled seams, chain stitch hems, specialty hardware, multiple fabric layers at critical junctions — makes alterations more technically demanding than standard tailoring. The key constraint is seam allowance.
Most jeans have approximately ¼ inch of seam allowance per panel at the side seams. This is the spare fabric tucked inside the seam that can be released to let a garment out. Four panels at a side seam (two per seam) means approximately 1 inch of total let-out — sometimes 1.5 inches on selvedge denim where the seam allowance tends to be more generous. Beyond that, there is no fabric to work with without sourcing additional material.
Taking in, by contrast, has more room. The fabric can be folded and trimmed rather than released, and the limit is more about proportion and aesthetics than about available material. The governing rule holds: bigger to smaller is always the more tractable direction.
3. The Eight Measurements
The Top Block
1. Waist
The most common alteration request — almost always because there is gapping at the center back when the wearer sits or bends forward. The instinct is to take in the side seams, because they're accessible. The correct approach is to work from the center back seam.
Here's why. Gapping at the center back means the waistband is too large relative to the body at that point. Taking in the side seams moves the back pockets closer together, which changes the visual proportions of the rear panel without actually solving the gapping problem at its source. Taking in the center back seam addresses the issue directly, preserving pocket placement and rear panel proportions while removing the excess at the precise location where it exists.
The center back is sewn on a flat felling machine. A tailor without one can still make this alteration — but the result may look different from the original construction, because the seam character changes. At FITTED Underground, we have the original machine, which produces an alteration that closely preserves the character of the original seam.
If additional inches need to be removed beyond what the center back seam can handle, the side seams can be opened as well. In total, you can safely reduce a waist approximately 3 inches — center back plus both side seams — and push to 4 inches if necessary. Beyond this, the alteration becomes structurally complex and the visual impact on pocket placement becomes significant.
For letting the waist out: the side seam allowance is the only source of additional fabric. Approximately ¼ inch per panel, four panels total — 1 inch maximum, or 1.5 inches on a selvedge pair with more generous allowance. This is the hard limit without adding new fabric. Remember: err on the side of larger. It's much easier to take in than to let out.
2. Hip
The hip alteration is more straightforward than the waist. Side seam adjustments work cleanly here — the hip seam is accessible and the flat felling machine is less critical at this location.
The same seam allowance constraints apply: approximately 1 inch of let-out is possible, sometimes 1.5 inches on selvedge. Taking in is more generous — both side seams plus the center back seam can be used, allowing reductions of up to approximately 3 inches.
One important caveat: the waist and hip are proportionally related. If you take in the waist substantially without adjusting the hip — or vice versa — you create a new fit problem at the transition between the two. The garment will pull or gap where the proportions no longer match. A good denim alteration tailor will flag this before proceeding and suggest addressing both dimensions together when one requires significant adjustment.
3 & 4. Front Rise and Back Rise
The rise is the one dimension that should, in almost all cases, be left alone.
The front rise cannot be raised without changing the total height of the waistband — there is simply no additional fabric to work with above the waistband top. It can be lowered, but the fly construction makes this genuinely complex, especially on a button fly where the buttons must be repositioned. The cost and effort rarely justify the result.
The back rise can be reduced by removing the waistband and taking in at the yoke junction. It can theoretically be raised by replacing the yoke entirely with a new, higher yoke — but this requires access to the original fabric to match the denim, and involves disassembling and reassembling a significant portion of the top block. Belt loops alone present a serious obstacle: each loop is attached with multiple bartacks at top and bottom, and removing them without damaging the waistband or the underlying fabric is painstaking work.
Rise is the one dimension that cannot be meaningfully corrected after the fact. Get it right at purchase — or at the point of a custom order.
The honest guidance: unless the rise makes the garment genuinely unwearable, don't attempt this alteration. The labor involved is substantial, the result is rarely perfect, and the cost reflects both. This is precisely why getting the rise right at the point of purchase — or at the point of a custom order — matters so much. Rise is the one dimension that cannot be meaningfully corrected after the fact.
The Leg Taper
5. Thigh
Similar to the hip but with one fewer seam — the thigh has an inseam and an outseam rather than two side seams. Maximum let-out is approximately ½ to ¾ inch. Taking in is more generous, as both seams can be used.
The thigh works in proportion with the knee. When adjusting the thigh, adjust the knee as well — the taper between the two creates the visual character of the leg, and changing one without the other produces an awkward transition.
6 & 7. Knee and Leg Opening
Here is where selvedge denim introduces a specific complication that standard tailoring doesn't have to consider.
On a pair of selvedge jeans, the self-finished edge of the fabric runs along the outseam. When the jeans are cuffed, the selvedge is visible — and the train track fade that develops along it over years of wear is one of the distinctive pleasures of owning selvedge denim. Any alteration to the outseam disrupts that edge and, potentially, that fade.
If you plan to cuff your jeans, leg narrowing should go through the inseam rather than the outseam. This preserves the selvedge edge exactly as it was. It also presents a technical challenge: narrowing through the inseam on a finished pair of jeans requires sewing through the cylinder of a completed leg opening — a specialty operation that requires the right machine and the knowledge to use it correctly. Most general tailors cannot do this well. It is one of the areas where specialist denim experience and equipment produce a meaningfully better result.
If you don't plan to cuff, an outseam adjustment is simpler and the selvedge concern is less critical.
Maximum let-out at the knee and leg opening: approximately ½ to ¾ inch, constrained by the same seam allowance limits. Taking in: more generous, limited primarily by the desired proportion of the leg.
8. Inseam Length
The most common alteration — and the most straightforward. Shortening an inseam is relatively quick work. The complexity depends on what kind of hem finish you want.
A standard hem takes less time and produces a clean, functional result. An original hem — where the chain stitch roping effect of the factory hem is preserved — takes more skill and time, requires a chain stitch machine, and is worth requesting specifically if you want to maintain the character of the garment. The difference is visible and meaningful to anyone who knows what they're looking at.
Lengthening the inseam is possible up to approximately 1 to 1.5 inches, achieved by releasing the existing hem, pressing the excess fabric flat, and creating a new hem at a lower point on the leg. Beyond 1.5 inches, original fabric is required — and matching denim that has been worn and faded is effectively impossible to source. This reinforces the governing principle one more time: when buying raw denim, err on the side of longer rather than shorter. A hem can always be taken up. It cannot always be let down.
The Alteration as an Act of Slow Fashion
A pair of jeans that doesn't quite fit anymore is not a pair of jeans to discard. It is a pair of jeans to alter.
This is what slow fashion means in practice — not just buying better things, but maintaining them. A well-timed alteration extends the useful life of a pair of jeans by years. A waistband taken in an inch when the fit starts to feel loose is an hour of work that keeps a garment in rotation for another decade. The alternative — buying a new pair — costs more, generates more waste, and produces none of the character that the existing pair has spent years accumulating.
A pair of jeans that doesn't fit anymore is not a pair of jeans to discard. It is a pair of jeans to alter. A well-timed alteration extends the useful life by years.
The earlier an alteration is made, the better. Before fades establish, before wear patterns set in, before the fabric has years of memory built into specific crease lines. A seam alteration on a dark, raw pair of jeans is nearly invisible. The same alteration on a pair with two years of fades will be more visible, because the new seam runs through fabric at a different stage of wear than the original. Not always a dealbreaker — but a reason to address fit issues sooner rather than later.
For FITTED Underground's alteration services — on our jeans and on jeans from other makers — visit fittedunderground.com/products/alteration-services.
What Comes Next
Alterations address fit. Repairs address structure — the crotch blowout, the thinning knee, the fraying pocket corner. The distinction matters because the approach is different, the skills required are different, and the timing is different. That's DU 306: How to Repair Raw Denim.
← Previous: DU 304 — How to Get Great Fades | Next: DU 306 — How to Repair Raw Denim →
Core Curriculum
Complete the core curriculum by reading these essential classes.
- DU 101 — What is Raw Denim?
- DU 102 — What is Selvedge Denim?
- DU 104 — Denim Weight Explained
- DU 201 — How to Buy Your First Pair of Raw Denim Jeans
- DU 204 — How Much to Spend on Raw Denim
- How It Works — FITTED Underground
Eric Steffen is the founder of FITTED Underground, a custom jeans and raw denim workshop at 108 Bayard Street in Williamsburg, Brooklyn. He has been making jeans by hand since 2014. Denim University is his attempt to share everything he's learned — about the history, the craft, and the culture behind the world's most enduring garment.
