Your body has one set of numbers. Clothing has about nine
The reason this question is annoying is not that sizing is hard. It is that every garment measures a different part of you, and each one has its own chart. A dress is sized off whichever of your bust, waist and hip is largest. Jeans go by waist alone. A suit jacket goes by chest. A t-shirt goes by a letter that means something different in the next shop. None of them agree, and none of them are trying to.
So rather than making you look up five charts, this takes your measurements once and answers all of them together. Every number it gives you comes from the same chart the dedicated page on this site uses, and each row links to that page if you want the working.
What to measure, and how
Use a soft tape, keep it level, and do not pull it tight. Measure over your underwear rather than over clothes. If you do not have a tape, a piece of string against a ruler works: mark the string where it meets, then lay it flat.
- Bust or chest. Around the fullest part, arms down. For a chest measurement keep the tape under your arms.
- Waist. Your natural waist, which is the narrowest part of your torso, usually just above the navel. This is almost never where your trousers sit, and using the trouser number is the single most common reason these charts come out wrong.
- Hip. Around the fullest part, roughly 8 in below the waist. Include everything, not just the hip bones.
- Neck. Around the base where a collar sits, with one finger under the tape so you can still breathe.
- Foot. Stand on paper, mark heel and longest toe, measure between the marks. Do it late in the day, when your feet are at their largest.
Why the largest measurement wins
For a dress, whichever of your three numbers lands in the biggest size is the size you buy. That is not a rounding convention, it is a fact about fabric: a garment that is too large can be taken in at a seam for very little money, and a garment that is too small cannot have fabric added. If your bust says 12 and your waist says 8, buy the 12.
The same logic drives the advice at the bottom of every result. Where two of your measurements disagree by more than one size, the honest answer is that no standard size is cut for your proportions, and the fix is a tailor rather than a different chart.
The number is not a fact about you
Clothing sizes are a manufacturing decision, not a measurement. There is no law requiring a US 8 to mean anything in particular, and vanity sizing has moved the labels roughly four sizes since the 1950s: a 1958 size 16 is close to a modern size 8. Two shops on the same street will put different numbers on the same body, and both are correct in their own system.
What this means in practice is simple. Treat every number here as the size to try first. When a listing publishes its own garment measurements, believe those over any general chart, this one included. And if you want to understand why a garment measurement never matches your body measurement, that gap has a name and its own page: ease.
Where to go for the detail
Each row in the result links to the page behind it, and those pages carry the conversions, the fit troubleshooting and the caveats this summary has to leave out. The dress size calculator explains which of your three measurements is driving your size and what to do when they disagree. The jeans size conversion handles the men's to women's crossover. The letter size conversion covers the S/M/L question, including the awkward cases where the honest answer is neither of the two sizes you were choosing between. For shoes, the shoe size converter goes from foot length to US, UK and EU in one step.