Safety & PPE Reference Library · Sizing, Fit & Identification

Hi-Vis Garment Sizing

How to size high-visibility vests, shirts and jackets for the clothing worn underneath, and how poor fit, tool belts and harnesses can reduce the visible coverage the garment was certified for.

Ref SP-0309ANSI/ISEA 107

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

An ANSI/ISEA 107 garment is certified with set amounts of fluorescent background and retroreflective material placed to show the body's outline from all sides. That certification assumes the garment is worn as designed: closed, on the outside, and sized so the material is not hidden or bunched. Size the garment for the outermost layer it will be worn over.

How to size it

Ask what will be worn underneath across the seasons: a T-shirt, a hoodie, an insulated jacket.
Measure chest over that layer, around the fullest part under the arms.
Use the maker's size chart. Vests often run in combined sizes (for example S/M, L/XL).
Try it on fastened. Check that the retroreflective bands wrap fully around and sit level.
Raise the arms and bend over. The garment should not ride up to bare the torso band area.

Fit and coverage

Situation	Effect on coverage	Sizing approach
Vest worn open	Front bands broken; outline lost	Size so it closes comfortably; use a breakaway closure if needed
Vest too small over a winter coat	Will not close; bands distorted	Size up or buy a Class 3 outerwear jacket
Garment far too large	Sags; bands sit low or fold	Choose the size that fits the outer layer, not larger
Tool belt worn over the garment	Hides lower bands	Use a longer garment or wear the belt underneath where safe
Fall protection harness	Straps cover bands	Use a harness-compatible vest with a D-ring opening
Jacket or rain gear over a vest	Vest hidden	Outer layer must itself be hi-vis to the needed class

Key points

The outermost layer is the one that counts.
Tall workers may need tall sizes so the bottom band stays at the waist.
Sleeve length matters for Class 3 sleeves; cuffs pushed up hide arm bands.
Breakaway vests are designed to tear away when snagged. Size them so normal movement does not open them.
Replace garments that have shrunk, faded or lost reflectivity.

Common mistakes

Buying one size for the whole crew.
Ordering summer sizes that do not close over winter layers.
Wearing a non-hi-vis jacket over a Class 2 vest.
Cutting or pinning a vest to make it fit.

Governing standards: ANSI/ISEA 107; 23 CFR 634.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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