The method that actually works
Measure yourself properly, store those numbers, and treat every brand's chart as a translation layer that may be wrong. That is the whole method. Everything else is refinement.
Measurements worth recording
Seven cover the large majority of online fit decisions: chest or bust, natural waist, hip, shoulder width, neck, inseam, and arm length. Add thigh and calf when buying trousers or fitted dresses.
Then understand ease, because garments are not built to your body
This is the part that explains most fit complaints. New Mexico State University Extension specifies 3 to 4 inches of ease on the bust, 1 to 2 inches from nape to waist, and 1 to 3 inches on the thigh. Ease is movement allowance built into the pattern.
For stretch knit the number goes negative — minus 2 to 0 inches. A fitted jersey garment is deliberately cut smaller than your body so it can stretch to fit.
If a brand charts a stretchy jersey at your bust measurement, the garment will be skin-tight. Charts rarely tell you the ease, which is why comparing chest numbers alone misleads.
What the research says about labels
Across more than 1,000 garments in 50 UK brands, only 64% matched their own chart within 1 cm. Average within-brand variance was 4.2 cm. Larger sizes were described worst, with chart accuracy falling to 54% at UK 20-22.
Plus-size shoppers report this most sharply. In a 2025 Vogue Business survey, sizing inconsistencies were cited by 46% of plus-size respondents against 34% of mid-size and 25% of straight-size shoppers.
A repeatable process
- Measure once in a fitted garment, standing naturally.
- Store the numbers somewhere permanent.
- For each garment, compare the chart to your numbers and account for ease.
- Check fit reviews for how the cut actually runs.
- For fitted or expensive pieces, sanity-check with a garment you already own.
The deeper problem
Sizes were assigned before measurement technology existed. The last comprehensive US anthropometric survey for apparel sizing was conducted in 1941 and does not reflect modern body shapes. Charts inherited from that era are still being used.
Related reading: how professionals measure and the scale of the mismatch.