Fit problems are often blamed on the sewer, the pattern or the body. In reality, fit is usually a relationship between several things: the body measurements, the pattern measurements, the intended ease, the fabric and the balance of the garment.
1. Measure the body consistently
Use a flexible tape, keep it level and measure over the kind of underwear or base layer the garment will be worn with. Do not pull the tape tight.
For many garments the chest/bust, waist and hip are obvious starting points, but back length, shoulder, sleeve length, rise or inseam can be equally important depending on the style.
2. Compare body measurements with finished garment measurements
A body size chart tells you who the pattern is intended to fit. A finished garment chart tells you the actual size of the garment.
The difference is the ease. Without understanding the ease, you cannot really understand the fit.
3. Separate wearing ease from design ease
Wearing ease gives the body enough room to move, sit and breathe. Design ease creates the silhouette — fitted, regular, relaxed or oversized.
Two garments can be labelled the same size and have very different finished measurements because they are designed to look different.
4. Choose size by the measurement that matters most to that garment
For a fitted top, chest or bust may be the controlling measurement. For trousers, hip may be more important. The best starting size depends on the style and where alteration will be easiest.
If you sit between sizes, blending sizes can be more sensible than forcing the whole garment into one size.
5. Correct length before chasing every circumference problem
A garment can look too tight or too loose simply because important horizontal levels are sitting in the wrong place. Check shoulder position, bust level, waist level, hip level, crotch depth and garment length as relevant.
6. Look at balance
Balance is the relationship between front, back and side seam positions when the garment is hanging on the body. If a side seam swings forward or backward, or the hem rises in one area, the problem may not be simple width.
This is why adding width everywhere is often the wrong correction.
7. Use a toile or test garment when the fabric is valuable
A test garment lets you check proportion, length, balance and major fit before cutting expensive cloth. It does not need every pocket or finish; it needs enough construction to behave like the real garment.
8. Remember that fabric changes fit
A rigid woven, soft woven and stretch knit can all produce different results from a similar pattern shape. Stretch and recovery are particularly important: more stretch does not automatically mean better fit.
Sewing Pattern Secrets
If you are looking for a large downloadable pattern library, I have been reviewing Sewing Pattern Secrets. I like that it combines patterns with written instructions and tutorial material rather than presenting patterns alone.
I have not personally sewn every pattern in the library. My recommendation is to look through the offer yourself and decide whether the styles and level of support suit the way you sew.
See Sewing Pattern Secrets