Use this when asking how tight a thermal or base layer should be, especially when the real goal is clean layering rather than compression.
What this tool is actually telling you
A base layer can be close-fitting without being a compression garment. The useful test is whether it layers smoothly and stays positioned during the movements you actually perform.
Use this as measurement-based guidance, not a guarantee of fit. Brand blocks, grading, fabric stretch, construction and personal preference can change the best size.
Inputs that make the answer stronger
- Enter values from the same measurement method or planning period.
- Check units and product-specific definitions before comparing results.
Worked example
Use the output to compare two real alternatives with the same assumptions rather than treating one number as a universal recommendation.
How to use the result for a real decision
Choose the product’s intended fit, then raise your arms, bend, sit and rotate to check hem, waistband, underarm and seam behavior before keeping it.
Why undergarment labels are especially variable
Band/cup relationships, compression, rise, edge tension and pattern geometry can change fit substantially between products. Use the label to locate a chart, not as a physical measurement.
Sources and verification
Undergarment sizing and fit claims are qualified where brand systems, cup progression, compression or product geometry can differ.
Questions people ask
Is the calculation a guarantee?
No. It provides transparent arithmetic or a planning estimate from the values entered.
What makes the result more useful?
Use consistent measurements and add garment-specific evidence such as a current size chart or a known-good reference garment.