4mm vs. 10mm coroplast campaign signs

The short answer

Choose 4mm coroplast (about 3/16 inch) for standard residential yard signs up to roughly 18×24 inches, where cost per sign and volume matter most. Choose 10mm coroplast (about 3/8 inch) for larger formats, exposed corners and roadside frontage, or any placement that has to stay flat and last the whole campaign season. Both are waterproof corrugated plastic, both take a full-colour print on both sides, and the right choice depends on where the sign will stand rather than on who is on it.

Side by side

Where 4mm is enough

Standard 4mm board is the default for high-volume, price-sensitive runs because it is light, waterproof and cheap to ship and store. For a front-yard sign on an H-stake, a door-to-door canvass drop or a stock of replacements held back for the final fortnight, it does the job, and the savings per sign add up across a large order. Our campaign yard signs are quoted against your placement plan, so tell us where they will stand and we will say whether 4mm is enough.

Where 10mm earns its place

The heavier 10mm board costs more per sign but stays flat and rigid where a thin panel would bow or flap. That matters on a windy corner lot, along highway frontage, or anywhere a sign has to survive months outdoors rather than a single weekend. Large roadside signs are also quoted with their posts and bracing, because the board is only part of what keeps a big sign standing. For more on sizes, stakes and sides, see our guide to yard sign specs.

The verdict

Pick 4mm for front yards, canvass drops, volunteer stock and any run where per-sign cost is the priority.

Pick 10mm for corner lots, highway frontage, large formats and signs that must stay flat for the full season.

Most campaigns mix both: mostly 4mm yard signs, plus a smaller batch of 10mm for key intersections. Orders start at 12 signs and come with a free mockup within 24 hours, with standard production of about 2 weeks. Read our campaign sign buying guide or browse every style we make.