Dress Size Calculator Guide

Dress sizes vary significantly between countries and brands, making online shopping particularly challenging. Understanding the differences between UK, US, and European sizing—and knowing your actual body measurements—is the key to finding clothes that fit well without endless returns.

This guide provides comprehensive size conversion charts, explains how to take accurate body measurements, and covers the reality of vanity sizing in UK fashion retail.

Women's Size Conversion

How to Measure

• Bust: Around fullest part, keeping tape level
• Waist: Natural waistline (narrowest point)
• Hips: Fullest part of hips/bottom

Letter Sizes

Men's Clothing Conversion

How to Measure Accurately

For the most accurate fit, take these measurements:

1. Bust: Measure around the fullest part of your chest, keeping the tape level and not too tight
2. Waist: Measure your natural waistline (narrowest point, usually above your belly button)
3. Hips: Measure around the fullest part of your hips and bottom
4. Inside leg: From crotch to ankle for trousers

Wear light clothing and stand naturally. Have someone help you for accuracy.

UK Retailer Size Variations

UK retailers are known to size differently:

Plus Size Conversion

Tips for Online Shopping

• Check the brand's specific size guide
• Read customer reviews for sizing feedback
• Compare measurements to clothes you own
• When between sizes, size up for comfort
• Check return policies before ordering

UK vs US vs EU Dress Size Conversion Chart

One of the biggest challenges when shopping online or abroad is converting between different sizing systems. The following guide covers the standard conversions between UK, US, and EU dress sizes:

• UK 4 = US 0 = EU 32
• UK 6 = US 2 = EU 34
• UK 8 = US 4 = EU 36
• UK 10 = US 6 = EU 38
• UK 12 = US 8 = EU 40
• UK 14 = US 10 = EU 42
• UK 16 = US 12 = EU 44
• UK 18 = US 14 = EU 46
• UK 20 = US 16 = EU 48
• UK 22 = US 18 = EU 50
• UK 24 = US 20 = EU 52

Note that these are general equivalents. Individual brands may vary by one or even two sizes from this standard conversion. Always check the specific brand's size chart when ordering from international retailers.

How to Measure Yourself Accurately

Getting accurate body measurements is the foundation of finding your correct dress size. Here is a step-by-step measuring guide:

• Bust: Measure around the fullest part of your chest, keeping the tape measure level and snug but not tight. Wear a well-fitting, non-padded bra for the most accurate measurement.
• Waist: Measure around the narrowest part of your natural waist, which is typically about 2.5 cm (1 inch) above your belly button. Bend sideways to find the crease point, which indicates your natural waist.
• Hips: Measure around the fullest part of your hips and bottom, usually about 20 cm (8 inches) below your waist. Stand with your feet together for consistency.

Use a soft fabric tape measure rather than a rigid metal one. If you do not have a tape measure, use a piece of string and then measure it against a ruler. It helps to have someone else take the measurements for you, as this improves accuracy, especially for the bust and back measurements.

Brand Variations in UK Sizing

Despite the existence of British Standards for clothing sizes, there is no legal requirement for UK retailers to follow them. This means that a size 12 at one shop may fit very differently from a size 12 at another. Here are some well-known variations among popular UK brands:

• Marks and Spencer: Generally considered to run slightly generous. Many shoppers find they need a size smaller than usual.
• Zara: Known for running small compared to most UK brands. You may need to go up one or two sizes from your usual UK size.
• ASOS: Tends to be true to standard UK sizing. Their own-brand clothing is designed to match the measurements listed on their size guide.
• Next: Generally consistent and true to size, making them a reliable benchmark for UK sizing.
• H&M: Uses European sizing as standard. Their sizes tend to run smaller than typical UK sizes, so check their conversion chart.
• Primark: Sizing can be inconsistent between garments and collections. Trying on in store is recommended.

This phenomenon, sometimes called vanity sizing, means that brands may label garments with smaller size numbers to make customers feel better about their size. It has become more prevalent in the UK fashion industry over the past two decades, with some studies suggesting that a modern UK size 14 has measurements closer to what was historically a size 16 or 18.

Plus Size Clothing in the UK

The UK plus size market has grown significantly, with more retailers offering extended size ranges. Standard UK plus sizes typically begin at size 16 or 18 and extend to size 32 or beyond. Here is what you should know:

• Size range: Most UK high street retailers now offer sizes up to at least 24 or 26. Specialist plus size retailers such as Yours Clothing, Simply Be, and Evans offer sizes up to 32 or 34.
• Online availability: ASOS Curve, boohoo Plus, and PrettyLittleThing Plus offer extensive ranges up to UK size 30 at affordable prices.
• Fit considerations: Plus size garments are designed with different proportions, not simply scaled-up versions of smaller sizes. Look for brands that offer dedicated plus size pattern cutting for a better fit.
• Measurement tips: When measuring for plus sizes, ensure the tape measure sits flat without digging into the skin. Take measurements over light clothing rather than directly on skin for comfort and accuracy.

Frequently Asked Questions

Why do I wear different sizes in different shops?

There is no legally enforced sizing standard in the UK. Each brand creates its own size chart based on its target customer. Vanity sizing, where brands use smaller size numbers for the same measurements, is common. The best approach is to refer to each brand's specific size chart using your actual body measurements in centimetres rather than relying on your usual size number.

How do I convert my UK dress size for shopping on US websites?

The general rule is to subtract 4 from your UK size to get the US equivalent. For example, UK 12 equals US 8, and UK 16 equals US 12. However, some US brands use their own sizing, so always check the retailer's size chart and compare your measurements in inches or centimetres.

What if my measurements fall between two sizes?

If your bust, waist, and hip measurements span two different sizes, the general advice is to choose the larger size for a more comfortable fit. For structured garments like blazers and fitted dresses, sizing up allows for easier alteration by a tailor. For stretchy fabrics, you may be comfortable in the smaller size.

Do UK dress sizes change with age?

UK dress size numbers remain consistent, but body proportions can change with age. Brands such as Marks and Spencer and JD Williams design specific ranges for mature women that account for common changes such as a slightly higher waist and different bust proportions. Taking fresh measurements every six to twelve months ensures you are always buying the right size.

UK Dress Sizing: History and Standards

The UK dress sizing system has a long and somewhat chaotic history. Unlike many countries, the United Kingdom does not enforce a mandatory national sizing standard for clothing. British Standard BS 3666, which was originally published in 1982 to provide consistent sizing guidelines, was withdrawn in 2002 and has never been replaced. This means that UK clothing sizes are determined entirely by individual brands and retailers, leading to significant inconsistency across the high street.

Research by consumer group Which? found that a UK size 12 dress can vary by up to 4 inches (10 centimetres) in the waist measurement between different high street retailers. For example, a size 12 at one store might fit someone with a 28-inch waist, while the same labelled size at another store accommodates a 32-inch waist. This phenomenon, often called "vanity sizing," has become increasingly common as retailers gradually increase the measurements within each size label to make customers feel better about the size they wear.

The UK clothing market is worth approximately 60 billion pounds annually, with women's wear accounting for the largest share at around 28 billion pounds. Online fashion sales now represent over 30 percent of total clothing purchases in the UK, making accurate sizing more important than ever. ASOS, one of the UK's largest online fashion retailers, reports that approximately 30 percent of clothing purchased online is returned, with incorrect sizing being the most common reason. This costs the UK fashion industry an estimated 7 billion pounds per year in returns processing.

When shopping internationally, UK consumers need to be aware that US sizes run approximately two sizes smaller in numerical terms (a UK 12 is roughly equivalent to a US 8), while European sizes use a completely different numbering system based on centimetres (a UK 12 is approximately an EU 40). Australian sizes are the same as UK sizes for most brands.

Practical Dress Size Tips for UK Shoppers

• Always measure yourself before ordering online: Use a soft tape measure to record your bust, waist, and hip measurements in both centimetres and inches. Compare these against the specific retailer's size chart rather than relying on your usual UK dress size, as sizes vary significantly between brands.
• Check retailer-specific size guides: Major UK retailers including ASOS, Next, Marks & Spencer, and John Lewis all publish detailed size charts on their websites. These are based on their own patterns and are more reliable than generic UK size charts.
• Consider body shape, not just size: UK retailers increasingly offer clothing designed for different body shapes, such as petite (under 5 foot 3), tall (over 5 foot 8), and curve ranges. Choosing the right fit category can be more important than getting the right numerical size.
• Keep a size diary: Record which size fits you at each retailer you shop with regularly. This saves time and reduces returns when reordering from the same brand.

Dress Sizing Questions

Dr. Sarah Chen, PhD

Research Scientist, Public Health

Sarah holds a PhD in Public Health from the University of Edinburgh and has published research on UK health metrics and obesity trends. She translates complex medical data into practical, accessible guidance for everyday readers.