How To · Fashion · Basics
The Complete Guide to Finding Your Size
Sizing is not universal, and your body is not the problem. This is how to measure yourself properly and navigate the maze of vanity sizing, international standards, and brand variations.
5 min read · IrisSize is a conversation between your body and a brand's design choices. Two brands' size 8s can fit completely differently because of cut, fabric, and the designer's intended silhouette. This isn't a failure on your part—it's the reality of how clothes are made.
The solution is twofold: know your actual measurements, and learn to read a brand's size chart like you're fact-checking a resume. Once you have these two pieces of information, you'll spend less time in fitting rooms and more time in clothes that work.
Your measurements don't change. The numbers on tags do.
What you'll need.
- 01Soft measuring tape
- 02Mirror
- 03Notebook or phone
- 04Brand size charts
- 05Customer reviews
Step one · 2 minutes
Gather your measuring tools
You need a soft measuring tape (the kind used in sewing, not a metal one). Wear something fitted but not tight—a tank top and leggings work well. Stand in front of a mirror so you can see what you're doing. Have a notebook or phone ready to record numbers. If you don't have a soft tape, order one online for under $5, or ask a tailor to take your measurements for you.
Soft measuring tapes are flexible and won't dig into your skin, giving you accurate readings.
Step two · 3 minutes
Measure your bust, waist, and hip
Bust: Measure around the fullest part of your chest, keeping the tape parallel to the ground. Waist: Measure around your natural waist (the narrowest part, usually where you bend). Hip: Measure around the fullest part of your hip and thigh, usually 8–9 inches below your waist. Keep the tape snug but not tight—you should be able to fit one finger underneath. Write down all three measurements in inches or centimeters, depending on the brand you're shopping.
Measure twice. The second time is usually more accurate because you know what you're doing.
Step three · 2 minutes
Find the brand's size chart before you buy
Every brand publishes a size chart, usually linked near the size selector on their website or in the product description. Download it or screenshot it. Compare your measurements to theirs—not to generic 'small, medium, large' labels. A brand's size 8 might be cut for a 32-inch bust; another's might be 34 inches. The chart is your truth, not the number on the tag.
If a brand doesn't publish measurements, email their customer service and ask. Reputable brands will provide them.
Step four · 2 minutes
Account for fit preferences and fabric
Do you like a fitted silhouette or room to move? A loose linen shirt will fit differently than a structured cotton blazer. Check the product description for fit notes—'slim fit,' 'relaxed,' 'oversized'—and read customer reviews that mention fit. If reviews say 'runs small,' you might size up. If they say 'generous,' you might size down. Fabric matters: stretchy knits forgive fit issues; rigid fabrics don't.
Filter reviews by 'verified purchase' and look for comments from people with similar body types or fit preferences.
Step five · 1 minute
Order with a return plan
Even with perfect measurements, fit is subjective. Order the size the chart recommends, but have a backup plan: know the brand's return window, check if returns are free, and understand their exchange policy. Some brands let you order multiple sizes and return what doesn't work. This is a legitimate strategy, not cheating.
Screenshot the size chart before you order. If the item arrives and doesn't fit, you'll have proof of what you ordered based on.
Step six · Ongoing
Build a personal size reference
Keep a running list of your size in brands you buy from regularly. Note if you're a 6 in one brand and an 8 in another. Over time, you'll recognize patterns—certain designers cut smaller, others run large. This list becomes your personal sizing bible and saves you time on future purchases. Update it as your body changes, which is normal and expected.
Store this list in your phone's notes app or a spreadsheet. Include the brand name, size, fit notes, and the year you bought it.
How to know it works
You've nailed your size when you can shop with confidence, try things on less often, and feel comfortable in what you buy. You're no longer second-guessing the tag or blaming your body.
Questions at the mirror.
What if I'm between two sizes on the chart?
Check the product description for fit notes. If it's described as 'fitted,' size up. If it's 'relaxed' or 'oversized,' size down. Read reviews to see what others did. When in doubt, size up—it's easier to tailor down than to stretch fabric out.
My measurements don't match any standard size. What do I do?
You're not alone. Many people don't fit neatly into one size. Find the size that matches your largest measurement (usually bust or hip), then look for styles with adjustable elements like drawstrings, belts, or ruching. Tailoring is also an option for pieces you love.
Should I measure myself or have someone else do it?
Having someone else measure you can be more accurate because they can keep the tape level and snug without you tensing up. But if you're alone, a mirror and patience work fine. The key is consistency—measure the same way each time.
How often should I remeasure?
Once a year is standard, or whenever your body changes significantly. Your measurements might shift with seasons, fitness routines, or life events. It's not a failure—it's just information.