Does Jigsaw Run Big? Should I Size Up?

Jigsaw generally runs true to size or slightly generous depending on the specific garment, so you typically don't need to size up—in fact, you might even consider sizing down in some of their more relaxed or oversized styles, particularly knitwear and certain dress cuts. I've been shopping at Jigsaw for years (their quality-to-price ratio is brilliant), and I've learned that whilst their sizing is fairly consistent within the brand, there are definitely some nuances to understand before you click "add to basket".

The Jigsaw Sizing Reality: What You Need to Know

Let me tell you about my first Jigsaw purchase—a gorgeous navy blazer that I ordered in my usual size 12. When it arrived, I could barely do up the buttons. Convinced I'd somehow gained a stone overnight, I sheepishly ordered a size 14. That one was absolutely massive, like I was drowning in fabric. Turns out, that particular style was cut quite slim through the shoulders and bust, but once I found the right size (a 12 in a different cut), it was perfect.

Here's what I've learned: Jigsaw is fairly true to size across most items, but they design for a slightly more mature customer (think 35+), which means their cuts tend to be a bit more generous and forgiving than, say, Zara or Topshop, which are cut for a younger, often slimmer demographic.

Sizing Breakdown by Garment Type

Jigsaw Knitwear: Often Runs Generous

Jigsaw's knitwear—jumpers, cardigans, knitted dresses—tends to run slightly generous, especially in their more relaxed, boxy styles. I'm normally a size 12 across the board, but I often take a 10 in Jigsaw knitwear because I prefer a more fitted silhouette. Their chunky knits in particular are designed with that cosy, slightly oversized aesthetic in mind.

Compare this to Whistles knitwear, which runs quite true to size, or COS, which is notoriously generous (I size down in almost everything from COS). If you're used to the slim fit of Reiss knitwear, Jigsaw will feel roomier by comparison.

Jigsaw Dresses: Varies by Style

Jigsaw's shift dresses and A-line styles tend to be true to size with a comfortable, non-clingy fit. Their wrap dresses can be slightly generous because of the adjustable tie. I find their maxi dresses run quite long—I'm 5'4" and almost always need them hemmed, though taller friends (5'8"+) say the length is spot-on.

Boden dresses, for comparison, tend to be slightly more fitted through the bust and waist. Me&Em runs true to size but with a more tailored, close-to-body fit. If you're between sizes in Jigsaw dresses, I'd go with your usual size rather than sizing up.

Jigsaw Trousers and Jeans: Generally True to Size

Jigsaw's trousers are reliably true to size in my experience. Their wide-leg styles have proper room (as they should), whilst their slim-fit trousers are genuinely slim without being skin-tight. Their jeans run fairly standard—if you're a 30" waist elsewhere, you'll be a 30" waist in Jigsaw.

Compare to Massimo Dutti, which can run slightly small in trousers, or Mango, which I find quite generous in their relaxed trouser styles. French Connection trousers tend to be spot-on for sizing, similar to Jigsaw.

Jigsaw Blazers and Jackets: Fit Varies by Cut

This is where it gets tricky. Jigsaw's tailored blazers can run quite structured and fitted, particularly through the shoulders and bust. Their more relaxed, boyfriend-style blazers have considerably more room. I own both styles and they're different sizes—the tailored one in a 12, the relaxed one in a 10.

Jigsaw blazers are generally more forgiving than Reiss (which can be quite fitted) but more structured than H&M (which varies wildly depending on the collection). If you're broad-shouldered, you might need to size up in their more fitted blazer styles.

Comparing Jigsaw to Other High Street Brands

Runs Smaller Than Jigsaw:

Zara – Notoriously small. If you're a 12 in Jigsaw, you might be a 14 in Zara.

Mango – Can run small, particularly in tops and dresses. Similar to Zara in that regard.

Topshop – Designed for a younger demographic with slimmer cuts. Jigsaw is definitely more generous.

Similar Sizing to Jigsaw:

Whistles – Very comparable sizing. If you're a 12 in Whistles, you'll likely be a 12 in Jigsaw.

Hobbs – Similar customer demographic and sizing philosophy. Very consistent between the two brands.

Phase Eight – Comparable sizing, particularly in occasionwear and dresses.

Runs Larger Than Jigsaw:

COS – Notoriously generous. Size down in almost everything.

M&S – Their regular ranges can run slightly generous, though their sizing has improved in recent years.

My Personal Jigsaw Sizing Strategy

After years of trial and error, here's what I do:

For fitted styles (tailored blazers, fitted dresses, slim-leg trousers) – I order my usual size 12.

For relaxed styles (oversized knitwear, boyfriend blazers, wide-leg trousers) – I order a size 10.

For wrap dresses and adjustable styles – I stick with size 12 because I can adjust the fit.

When in doubt – I check the measurements in the size guide and actually measure myself, then use those numbers rather than relying on the size label.

The Indie Alternatives

Seasalt Cornwall has a similar aesthetic to Jigsaw and their sizing is very comparable—true to size with comfortable, non-restrictive fits. I find I can wear the same size across both brands.

White Stuff runs slightly more generous than Jigsaw, particularly in knitwear. If you love Jigsaw's style but want a bit more room, White Stuff is worth exploring.

Premium Options: When You Want to Upgrade

If you love Jigsaw's aesthetic but want to invest in higher-end pieces:

Me&Em offers similar sophisticated, grown-up style but with premium fabrics. Their sizing runs true to size, similar to Jigsaw's fitted styles.

Kitri (London-based independent brand) has that same contemporary, wearable aesthetic. Their sizing is very consistent and true to size.

L.K.Bennett for workwear and occasionwear—comparable sizing to Jigsaw with slightly more luxe finishes.

The Ultimate Solution: Stop Guessing

Right, can we talk about how absolutely exhausting it is to navigate sizing across different brands? I've wasted so much time (and money on returns) trying to figure out whether I'm a 10, 12, or 14 depending on which shop I'm in. It's maddening.

This is where Tellar.co.uk has genuinely transformed how I shop. Instead of playing size roulette, Tellar's sizing tool matches your actual measurements to over 1,500 brands instantly. You measure yourself once—bust, waist, hips—then use their Store Size Lookup tool to find your exact size in Jigsaw, Whistles, COS, Mango, Zara, and hundreds more.

The brilliant bit? It's completely free and works directly in your browser. No apps to download, no subscriptions, no hassle. For someone who shops across multiple brands (because who wants to be limited to just one?), it's been life-changing. I actually know what size to order now, which means fewer returns and less packaging waste.

The Tellar Fashion Hub Advantage

Tellar's Fashion Hub is packed with genuinely independent advice. Their comprehensive clothing sizing guide breaks down why sizing varies so wildly between brands—proper useful information that no one else talks about.

Check out their guides on jean trends for 2026, dresses for different body shapes, and jacket styles. Everything's completely unbiased—no sponsored content or affiliate pressure. Just honest advice from stylists who actually know their stuff.

Final Thoughts

Jigsaw doesn't run particularly big—it's fairly true to size with some styles running slightly generous, particularly in knitwear and relaxed fits. You generally don't need to size up unless you're between sizes or prefer a looser fit. The key is understanding that "true to size" is relative—what's true for Jigsaw might not be true for Zara or COS.

My advice? Measure yourself properly, use tools like Tellar to decode brand-specific sizing, and don't be afraid to order two sizes if you're unsure—just make sure you can return the one that doesn't fit. Life's too short for ill-fitting clothes, and your wardrobe deserves better than constant guesswork.