How to Tell If Secondhand Clothing Has Been Altered (A Hands-On Guide From Someone Who Checks This Every Day)

I check somewhere between twenty and fifty garments a week. Coats, shirts, polo shirts, trousers, jackets. And one of the things I look for every single time, before I even think about the label or the price, is whether the piece has been altered. Not because altered clothing is automatically bad. It is not. But because an alteration changes the garment in ways that are not always obvious, and if you do not know how to spot it, you can buy something that no longer fits the way it should, cannot be resized further, or has had its structure quietly ruined by someone with a sewing machine and good intentions.

This guide covers everything I actually do when I inspect a secondhand piece for alterations. Step by step, garment type by garment type, with the specific things to look for and what they mean in practice.

Why it matters whether secondhand clothing has been altered

Before we get into the how, it is worth being clear about the why. There are a few distinct reasons you want to know.

Fit. A garment altered for someone else's body may fit you strangely even if the labelled size is correct. A trouser taken in at the waist but not the seat will pull. A jacket with a shortened sleeve may feel tight at the cuff even though the chest is fine.

Resizing potential. If a piece has already been let out to its maximum, there is nothing left in the seams. You cannot make it bigger. Knowing this before you buy saves a frustrating conversation with a tailor later.

Value. A good professional alteration on a quality brand piece can actually be neutral or even positive. A bad amateur alteration, or one that has removed original details, reduces the resale value noticeably. I have passed on Ralph Lauren Oxford shirts that were otherwise near perfect, simply because someone had taken them in so aggressively that the side seams sat halfway around the back.

Authenticity and originality. On true vintage pieces, original hems, original buttons and original stitching are part of what makes the garment worth buying. An alteration that replaces or removes original construction detail changes the character of the piece.

The six signs that secondhand clothing has been altered

These are the specific things I look for, in the order I check them. Do all of these and you will catch virtually every alteration, whether it was done professionally or at home.

1. Turn it inside out and look at the seams

This is the single most reliable step. Turn the garment completely inside out before you do anything else. Most alterations leave what I think of as stitching fingerprints, small inconsistencies that give the game away immediately if you know what you are looking at.

Look for mismatched thread colour along any seam. A garment that left the factory with a single consistent thread throughout will have a seam that looks uniform from end to end. If one section of a side seam has slightly darker or lighter thread, or a thread that is noticeably thicker or thinner than the surrounding stitching, something has been re-sewn there.

Look at the stitch spacing. Original factory stitching is extremely consistent, produced by machines calibrated to run at a fixed tension. Altered stitching, even professional hand stitching, tends to have slight variations in the distance between each stitch. Hold the seam up and look along its length. A section that was re-sewn often has a visibly different rhythm.

Look for seam allowances that appear newly cut or freshly overlocked compared to the rest of the garment. On a jacket from the nineties, the original overlocking will have aged and softened slightly. A section that has been re-done will look newer and crisper, often in a slightly different colour.

2. Check for press lines, fading marks and old needle holes

This is the one most people miss, and it is often the most conclusive. When a seam is opened and re-sewn in a different position, the fabric retains a memory of where it used to be. That old fold creates a visible press line, a faint crease in the fabric that does not align with the current seam. It often shows as a slightly lighter or darker stripe running parallel to but beside the existing seam.

On denim especially, you can also see ghost marks where old stitching used to be. The needle holes from the original construction leave a row of tiny dots in the fabric, and if the seam has been moved, those dots no longer line up with the current stitch line. Look for these on the inner thighs of jeans, along the side seams of jackets and on trouser legs.

On lighter coloured fabrics, cotton shirts and chinos particularly, a previous hem or tuck can show as a faint horizontal line across the fabric where the fold used to sit. This is called a hem mark, and it tells you clearly that the garment was at some point a different length.

3. Inspect the hem closely

Hems are the most commonly altered part of any garment. Trousers, skirts, dresses, jackets and shirts all get hemmed regularly, and the hem is usually where the alteration is most visible if you look properly.

On trousers, a factory hem typically uses a specific finish suited to the fabric. On denim, look for the original chain stitch hem. A shortened pair of jeans that has been rehemmed will usually have a straight lock stitch instead, which is a clear sign it has been altered. Some tailors do attempt to preserve the original hem by a technique called a "hidden hem" or reattaching the original factory hem, but even then the join between the original hem tape and the new stitching is usually visible inside the leg.

On suit trousers and dress trousers, the hem is typically blind stitched from the inside. If you can see any stitching visible on the outside of the trouser at the hem, the blind stitching has either broken down or has been redone by someone less experienced.

On jackets and coats, the sleeve hem is another high-probability alteration point. Turn back the cuff slightly and look at the interior. A factory sleeve hem on quality menswear like a Lacoste harrington or a Tommy Hilfiger blazer will be clean, consistent and finished in a way that matches the lining. A shortened sleeve will often show a different finish at the cut edge.

4. Check the waist and side seams for size alterations

Taking in or letting out the waist or side seams is the most common structural alteration. This is where you find the clearest evidence of a garment being resized.

Inside the waistband of trousers, look for extra fabric or the absence of it. A garment that has been taken in will have the original fabric folded back on itself or trimmed away, with new stitching sitting proud of the original. A garment that has been let out to near its limit will have almost no seam allowance left inside the seam, sometimes just a few millimetres, and you may see old stitch holes or fading where the previous seam sat.

On shirts and jackets, run your fingers along the side seams inside. The original seam allowance on quality garments is typically around 15 to 20mm. If you find significantly less than that, the garment has probably been taken in at some point. If you find old needle holes running parallel to the current seam at a wider point, it has been let out.

A garment that has been taken in at the side seams on both sides simultaneously to reduce the overall size will sometimes show a very slightly asymmetric result, where one side seam sits slightly further forward or back than the other. This is difficult to see on a hanger but becomes obvious when the garment is on a body.

5. Look at the shoulders and structure of jackets and coats

Shoulder alterations are the most complex and expensive kind of alteration, and they are relatively rare as a result. But they do happen. More importantly, the shoulder area of a jacket or coat can tell you a lot about whether the garment has been altered elsewhere, because structural changes to the body of a jacket often affect how the shoulder sits.

If the shoulder seam of a jacket sits visibly behind or in front of your actual shoulder, and the rest of the fit seems fine, this can sometimes indicate the jacket has been taken in through the body significantly, pulling the shoulder seam off its original position.

On the inside of a jacket, look at the area around the sleeve head where the sleeve is set into the armhole. On a professionally altered jacket, this will be tidy. On one that has had a sleeve shortened from the shoulder rather than the cuff, which is the more complex method used when cuff details need to be preserved, you will often find that the original machine stitching has been partially replaced with hand stitching. As a StyleForum tailor memorably put it, suit sleeves are factory sewn by machine at the bottom, and when altered, the new stitching is usually done by hand, which looks noticeably different up close.

6. Check for mismatched details and replaced components

Buttons, zippers and linings are sometimes replaced as part of an alteration, or simply because the originals wore out. A replaced button sounds like a minor issue but on a vintage polo shirt or a classic Lacoste piece, original branded buttons are part of the garment's character and value. If three buttons on a shirt match perfectly and one looks slightly different in colour, texture or weight, it has been replaced.

On a jacket or coat, check whether the lining matches throughout. A partial lining replacement, sometimes done when a lining tears during an alteration, will show as a slightly different sheen or weight in one section compared to the rest. Look particularly at the lower back panel of a jacket lining, as this is where tailors often have to open the garment to work on the body seams.

Check that any pattern, check or stripe continues consistently across seams. On quality cloth, the pattern should match at side seams and sleeve heads. If the pattern suddenly shifts at a seam, the seam has been moved and the pattern match has been lost in the process.

Does an alteration mean you should not buy the piece?

Absolutely not. This is the nuance most guides miss, and it matters.

A well done professional alteration on a quality garment can be completely fine to buy, sometimes better than the unaltered version because the previous owner already paid to have it fitted properly. I regularly buy and sell pieces that have had hems shortened, sleeves adjusted or side seams taken in, provided the alteration was done well and the garment still has room to be adjusted further if needed.

The alterations I walk away from are:

• Amateurish work on quality pieces. Uneven stitching, puckered seams, visible thread on the outside of hemlines, or stitching that is pulling the fabric out of shape. This kind of work is often difficult to reverse without damaging the fabric.
• Alterations that have used all the seam allowance. If a garment has been let out to its absolute limit, there is nowhere left to go. It cannot be made larger. On a piece with a heritage label like Ralph Lauren or Hugo Boss, this can mean buying something with a significantly reduced future value.
• Alterations that have removed original details. A vintage Ralph Lauren shirt where someone has cut off the original Polo collar and replaced it with a different one, or a jacket where the original lining has been replaced with something unmatched. These are structural changes that alter the garment's identity.
• Shoulder alterations on jackets and coats. These are so complex that they rarely come out perfectly, and a jacket whose shoulders do not sit right will never feel comfortable no matter how well everything else fits.

The alterations I am often relaxed about are clean, professional hems on trousers and sleeves, side seam adjustments that still leave seam allowance, and replaced buttons where the replacement matches well. These are part of the normal life of a quality garment.

A specific note on designer brand pieces

When you are buying secondhand designer clothing, Ralph Lauren, Tommy Hilfiger, Lacoste, Hugo Boss and similar brands, the alteration question has an extra layer. These garments were made well to begin with, which means they were usually built with reasonable seam allowances and quality construction that responds well to alteration. It also means the original details matter more to their value and character.

If you are ever unsure about a specific brand's construction and what to look for inside, my guides on whether Tommy Hilfiger is worth buying secondhand and whether Lacoste is worth buying secondhand go into detail about how these brands construct their garments, which makes it much easier to recognise when something is not original.

On vintage pieces from the seventies and eighties particularly, it is worth knowing that pre-1980s garments were often made with generous seam allowances precisely because the expectation was that clothing would be altered to fit and altered again as bodies changed. Finding a well made vintage piece with evidence of a previous alteration is not unusual. It is often just a sign that someone valued the garment enough to have it properly fitted.

How to check for alterations when buying online

Buying secondhand online means you cannot turn the garment inside out yourself, which makes this harder but not impossible. Here is what I do.

Ask the seller directly whether the garment has been altered, and specifically ask if anything has been hemmed, taken in, let out, or repaired at the seams. A good seller will know and tell you. If they are unsure, that is useful information too.

Request interior photos. Ask for close up shots of the main seams inside the garment, the hem from the inside, and the waistband or cuff area. These photos will usually show you everything you need to see: thread mismatches, seam allowance width, old press lines.

Ask for measurements rather than relying on the size label. A garment that has been taken in significantly may have a size 42 label but measure like a 38. Chest, waist, shoulder width, sleeve length and body length are the measurements that matter. For a more detailed guide on reading vintage clothing labels and understanding how sizing has changed over the decades, my complete guide to reading vintage clothing labels and tags covers this thoroughly.

Look carefully at the listing photos. Photos taken in good natural light will often show hem marks, seam shifting and fabric fading around altered areas if you look closely. Zoom in on the cuffs, the hem and the side seams. If the photos are too dark or taken from too far away to see the seams, ask for better ones.

A quick inspection checklist

Use this every time you pick up a secondhand piece, whether in a shop or at home when a parcel arrives:

1. Turn inside out. Check every seam for thread colour mismatches and stitch spacing differences.
2. Look along the side seams for old press lines, fading marks and needle holes from previous stitching positions.
3. Check the hem from the inside. Look at the hem tape, the finish and whether there is any evidence of a previous hem line above or below the current one.
4. Measure the seam allowance at the side seams and waist. Is there room left to alter if needed?
5. Check the sleeve hem and cuff. Look for a mismatch between the lining finish and the sleeve edge that might indicate shortening.
6. Check all buttons, zippers and the lining for replacements or mismatches.
7. On checked or striped fabric, check that the pattern matches across all seams.
8. If the garment is a jacket or coat, check the shoulder seam position and the sleeve head for hand stitching.

Buying secondhand well is a skill that builds with practice, and knowing how to read a garment properly is a big part of what separates a great find from an expensive mistake. If you want to see what carefully inspected, honestly described secondhand designer clothing actually looks like, you are welcome to browse the pieces we have available at Revaleur. Every piece we list has been through exactly the kind of checks described in this guide.