How to Know Your Clothing Size Across Brands: The Only Guide You’ll Ever Need
Author: Stylist and brand team at Tellar
Date: 2025
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Tired of guessing your size every time you shop?
If you've ever ordered clothes online, chances are you've experienced the disappointment of a perfect item arriving in the wrong size. One brand’s size 10 fits like another’s size 6. For many, online shopping is a cycle of trial and error.
At Tellar, we exist to fix that. This is your complete guide to understanding sizing differences, taking your own measurements, and using Tellar to get the perfect fit—first time, every time.
Why Clothing Sizes Are So Inconsistent
One of the biggest frustrations in fashion is the lack of standardised sizing. Here’s why your size varies so much from store to store:
1. There’s no universal sizing system
Sizing standards differ between countries:
UK 10 ≠ US 10 ≠ EU 40
Japanese and Korean sizes use completely different scales
Even UK sizes differ depending on the brand’s target market
2. Vanity sizing is real
Some brands deliberately make sizes more generous. What’s labelled as a UK 10 may actually measure like a 12, so customers feel flattered and more loyal to the brand.
3. Style and cut matter
Two size 12s can fit totally differently depending on design:
A fitted blazer vs. a flowy boho dress
A cropped jumper vs. a longline tee
Fit intent plays a huge role in how sizes feel.
4. Seasonal and manufacturing differences
Brands may update their size charts between seasons or use different factories, causing slight but noticeable shifts in fit—even within the same size.
The result? Guessing your size across stores is almost impossible.
The #1 Solution: Know Your Body Measurements
To eliminate size guesswork, the most powerful tool is your own body measurements.
You only need three numbers:
Chest (measured around the fullest part)
Waist (measured at the narrowest part)
Hips (measured around the widest part)
Once you have these, you can accurately compare your body to any brand’s sizing chart. The easiest way to do this is to use Tellar.co.uk. They have done all the hard work for you and will match your exact measurements to 1500 clothing brands size charts, so you can access your right size, anywhere, anytime for free! Download their app today!
How to take your measurements
Tellar.co.uk provide a free printable measuring tape on their website and app!
All you need is a soft tape measure (or a piece of string and a ruler). Here's how:
Chest: Wrap the tape around the fullest part of your bust, under your arms.
Waist: Find the narrowest part of your waist, usually above the belly button.
Hips: Measure around the fullest part of your hips and bum.
Record these numbers in either cm or inches. You can then create your profile at https://tellar.co.uk/create-your-profile to instantly see your recommended size across hundreds of stores.
Use Tellar to Find the Right Size Instantly
Knowing your measurements is just the start. Tellar takes it to the next level.
Instead of manually comparing charts on every store’s website, Tellar does the work for you.
Here’s how it works:
You enter your measurements once at Create Your Profile.
Visit the Store Size Lookup Tool.
Select a store like Zara, H&M, ASOS, or any brand in our database.
Instantly see the best-matching size for your body—and which stores run large or small.
You can even install our Chrome Extension (coming soon) to auto-detect your correct size while browsing your favourite shops online.
Clothing Size Conversion: UK, US, EU & More
Another common problem is converting sizes across different regions. Here’s a quick reference:
UK US EU
6 2 34
8 4 36
10 6 38
12 8 40
14 10 42
16 12 44
But this is just a starting point. The same UK size can have different measurements depending on the brand. Always check store-specific charts—or better yet, let Tellar do it for you.
Visit our Size Conversion Chart for full tables including CM/Inches.
How Brands Compare: Fit Differences You Should Know
Some brands are known to run small, large, or inconsistently. Here's a breakdown:
Zara
Zara generally runs small, especially in fitted dresses and trousers. A UK 10 may feel more like an 8.
→ See the full Zara Size Guide
H&M
H&M is hit or miss. Their basics run large, but trend pieces and dresses are often tighter.
→ Visit our H&M Size Guide
ASOS
ASOS sizing varies depending on the sub-brand (ASOS DESIGN, COLLUSION, etc). Always check the product info.
→ Read the full ASOS Size Guide
These inconsistencies are why Tellar cross-references each brand’s actual charts with your profile—to give you the most accurate recommendation.
Fit Style vs. Body Shape
Another reason sizing isn’t one-size-fits-all? Your body shape.
Two people with the same measurements may find different fits more comfortable depending on where they carry weight.
Hourglass: Smaller waist, larger hips and bust – may prefer brands with curve cuts.
Rectangle: Balanced shape – can wear straight cuts comfortably.
Pear: Narrow shoulders and wider hips – may need to size up for bottoms.
Also, fabric matters:
Stretchy fabrics like jersey or elastane blends can allow more size flexibility.
Rigid fabrics like denim and woven cotton have less forgiveness.
Tellar’s system factors these nuances in when recommending sizes.
What to Do If You're Between Sizes
Being between sizes is normal—and frustrating.
Here’s what to consider:
1. Check the fabric
If the garment has stretch, you can usually size down.
If not, size up for comfort.
2. Think about the fit you want
Tight, tailored, oversized—what’s the intended look?
3. Read reviews