COS Slip Dresses Resale Value

COS slip dresses: price by condition

Seller-declared grades, sterling with an approximate US dollar equivalent at £1 ≈ $1.33 (July 2026). What each grade means.

What holds its value across COS

• Oversized wool and wool-blend coats, which are the label’s signature and the thing buyers search it for by name
• Archive and limited-edition pieces, which are produced in small runs and are the only part of the range with a collectors’ element
• Plain, structured tailoring in neutral colours, which dates far more slowly than anything printed and stays saleable for years
• Heavier knitwear in merino and wool blends, which holds its shape where the cheaper high-street equivalents do not

What pulls COS resale value down

• Pilled knitwear, which is the commonest fault and shows immediately against the plain colours the label favours
• Faded blacks and washed-out greys, which are most of the range and where fading is most obvious
• Anything with a broken or replaced signature button or fastening, since the hardware is deliberately minimal and any substitute shows
• Basic jersey pieces, which are cheap enough new that a used one rarely justifies the postage on its own

Identifying and dating yours

1. The neck label reads COS rather than any sub-line, and the care label carries a product code buyers can search to confirm the season
2. COS sizing runs large and is cut deliberately oversized, so give flat measurements — buyers who have not worn the label before consistently order wrong
3. Photograph the shoulder seams and the inside of the coat, because the construction is most of why somebody chooses this label secondhand

What lifts any slip dress, whatever the label

Slip dresses live on the quality of the fabric, and silk versus polyester is the whole difference in price.

• Pure silk with good weight and drape
• Bias cut that hangs cleanly
• Designer and contemporary labels
• Adjustable straps in good condition

And what pulls one down

• Water marks on silk, which are often permanent
• Pulls and snags in the weave
• Stretched or frayed straps
• Polyester versions sold as silk

Working out what yours is worth

1. Check the composition label for silk content
2. Hang it and check the bias hangs straight
3. Inspect the straps and underarms

What to state in the listing

• Fabric composition and whether it is lined
• Bust, waist and shoulder-to-hem length
• Whether the straps are adjustable
• Bias cut or straight, and any pulls in the fabric

Fabric, cut and size: “100% Silk Bias Cut Slip Dress, Champagne, Size 10”. Fibre is the whole price difference here. Say bias cut if it is, and state the length — slips run from mini to full length.

Preparing and photographing it

1. Read the composition label: silk, satin-finish polyester and viscose are very different products.
2. Check whether it is lined and hold it to the light to test opacity.
3. Inspect the straps, any adjusters, and the bias seams for pulls or puckering.

1. On a hanger, full length, front, showing the drape
2. The composition label
3. The straps and any adjuster
4. The fabric close up, plus any snag, pull or mark

When it sells best, and handing it over

Strongest in summer and before the party season. Silk pieces sell year round to a steady audience.

Extremely light. Fold with tissue — silk and bias cuts crease and snag easily in transit.

What buyers ask

Does COS clothing hold its value?

Reasonably, and better than most of the high street, because the designs are plain enough not to date. Coats and tailoring do best; plain jersey basics are barely worth listing on their own.

What size should I list a COS coat as?

Give the label size and the flat measurements together. COS is cut oversized and the label size alone misleads more buyers on this brand than on almost any other.

How much is a COS slip dress worth?

Roughly £12 to £50 depending on condition, against £12 to £50 for slip dresses generally. The identification points above are what move a listing to the top of that range.

What the fees would take elsewhere

At the mid-range £31 for a COS slip dress, against what the commission marketplaces would deduct:

Seller-side rates verified 26 Jul 2026, percentages only — the per-order and processing charges those platforms add are excluded, so the real gap is wider.

Listing is free and there is no commission — read how to sell a slip dress for the title, handover and timing, or the general slip dress value guide if yours is not a COS.

See also: all COS value guides · value guides by brand · buying a slip dress · Clothing · condition grades.