Brand guide

Does Aritzia run small?

Mostly no — but its bottoms do, and the brand quietly runs two different size systems at the same time. We compared every Aritzia chart against Gap, Old Navy and Banana Republic.

By Sulaimon Salako, CEO of Styla · 27 July 2026 · 5 min read · How we source our data

If you've searched this, you've probably already found ten blog posts telling you Aritzia runs small based on how one jacket fitted one person. That's not an answer. So here's one built from the charts.

And a note before we start, because it matters: if you've measured yourself and Aritzia's own size guide still sent you the wrong size, that isn't a failure on your part. As you'll see below, one of Aritzia's charts has holes in it — measurements it simply doesn't cover. Following the instructions correctly can still produce the wrong answer.

The short answer

• Tops, dresses and outerwear: true to size. Aritzia tracks Gap and Old Navy closely.
• Bottoms: runs small. Expect to go one size up from your Gap number.
• Denim: a completely different system — numeric waist sizes, and generous.
• Above a 45″ bust: Aritzia doesn't make your size at all.

Tops: true to size

Aritzia publishes one chart across tops, dresses and outerwear — the measurements are identical in all three. Against the mainstream brands:

An Aritzia medium fits a 36–37″ bust. A Gap size 8 fits 36.25″. That's as close to agreement as two brands get. On tops, Aritzia does not run small.

Bottoms: yes, this is where it runs small

Aritzia's medium tops out at a 29″ waist. Gap's size 8 starts at 29.5″. Every row runs roughly one size tighter.

If you're a size 8 at Gap, you are most likely a large in Aritzia bottoms — not a medium.

The part nobody mentions: Aritzia runs two size systems

This is the finding that surprised us, and it explains a lot of confused reviews.

Aritzia sizes its bottoms alphabetically — 2XS through XXL — with genuine gaps between sizes. It sizes its denim numerically — 23 through 32 — in continuous one-inch steps with no gaps at all. Same brand, same body part, two incompatible systems.

Here's what that does to a real person. Take a 29.5″ waist:

She is a clean size 29 in Aritzia jeans and has no size at all in Aritzia trousers. Medium stops at 29″, large starts at 30.5″, and her measurement lands in the inch and a half between them.

And it isn't a one-off. Aritzia's bottoms chart leaves a gap at every step, and they widen as sizes go up: 1″ between XS and S, 1.5″ between M and L, 1.5″ between L and XL, and 1.75″ between XL and XXL. The bigger you are, the more likely Aritzia's trousers chart has no row for you — while its denim chart, in the same store, covers every inch from 23 to 32.

Where Aritzia stops

XXL is the largest size Aritzia publishes: a 43.5–45″ bust, 36.75–38.5″ waist, 45.5–47″ hips. Above a 45″ bust, there is nothing.

For context, Gap runs to a size 22 (47.75″ bust) and Old Navy to a size 30 (60.75″ bust). If you're above Aritzia's ceiling, the honest answer isn't "size up" — it's that this brand hasn't made anything for you, and Old Navy, Lane Bryant or Torrid have.

So what should you order?

• Tops, dresses, outerwear: take your usual Gap or Old Navy equivalent. S ≈ 4–6, M ≈ 8–10, L ≈ 12.
• Trousers and skirts: go one size up from your Gap number. If your waist lands in one of the gaps, size up rather than down — Aritzia's steps are wide enough that the smaller size will be tight rather than snug.
• Jeans: ignore the alpha sizing entirely. Use your actual waist measurement in inches and add nothing.
• Between an Aritzia bottoms size: check whether the item comes in denim sizing instead. You may get a genuine fit rather than a compromise.