Shipping$10 shipping per product, anywhere in the US*

ACM vs Aluminum Signs: Cost, Flatness and Mounting

Tomas Amaya

October 31, 2026Updated November 3, 20268 min read

A dental office's flat composite wall sign with a tooth logo hangs beside the entrance, above a post mounted patient parking sign with an arrow.

What Is the Difference Between ACM and Aluminum Signs?

A 12 x 18 inch 3 mm ACM sign is $64.99 and a 10 x 14 inch .040 aluminum sign is $59.99. Choose ACM for a larger panel that must stay flat on a wall, and aluminum for post, fence and parking signs. Both print in 3 business days in the USA and ship for a flat $10.

ACM is a 3 mm sandwich panel: two thin aluminum skins bonded to a solid core. An aluminum sign is a single .040 inch sheet of metal. Both are rigid, both are printed in full color, and both are built for outdoor use, but they suit different jobs.

The composite core makes ACM stiff across a wide face, so it stays flat on a wall at larger sizes. Solid .040 aluminum is thin metal that bends a little under load, which is fine on a post or fence where screws hold it at several points. It is the classic parking, address and regulatory sign.

Question 3 mm ACM sign .040 aluminum sign
Construction Two skins, solid core One solid sheet
Thickness 3 mm .040 in
Starting price 12 x 18 in, $64.99 10 x 14 in, $59.99
Printing Direct UV, 1 or 2 sides UV vinyl, 1 or 2 sides
Sizes online 12 x 18 to 24 x 36 in 6 x 24 to 36 x 24 in
Mounting options Grommets, 2 or 4 corners Holes, 4 patterns
Outdoor promise Weatherproof, permanent No rust, 5+ year guarantee
Production after proof approval 3 business days 3 business days

Both ship from the USA for a flat $10 per product to any address in the country.

Corner of a blank aluminum composite panel with the top skin peeled back to show two thin aluminum layers around a solid core

How Much Do ACM and Aluminum Signs Cost?

An ACM sign starts at $64.99 for 12 x 18 inches, and an aluminum sign starts at $59.99 for 10 x 14 inches. Each product page opens on a common size, and these are the sentences those pages print:

  • An 18" × 24" ACM Sign is $79.99. Artwork prep is $14.99 per item. Printed in the USA in 3 business days and shipped nationwide, flat $10 shipping to any US address.
  • A 12" x 18" Aluminum Sign is $74.89. Artwork prep is $14.99 per item. Printed in the USA in 3 business days and shipped nationwide, flat $10 shipping to any US address.
Sign Size Starting price
ACM sign, 3 mm 12 x 18 in $64.99
Aluminum sign, .040 in 10 x 14 in $59.99

The total moves with size, sides and options, and the product page updates it before you pay. Drilled holes and rounded corners are aluminum options; grommets are the ACM option. Shipping is a flat $10 per product. If you already have a file, AI image to print makes it print ready for $14.99 per item, and Design it for me builds the layout from scratch for $29.99 with two revisions, free on an item of $499 or more.

Which Material Stays Flatter on a Large Sign?

ACM stays flatter. The bonded core spaces the two skins apart, and that is what makes a composite panel stiff across a 24 x 36 inch face. Hang it on a wall with a few fasteners and the printed face reads as one smooth plane.

A .040 aluminum sheet is thin. On a post, the screws hold it tight at the top and bottom, and the size of most parking and address signs keeps the span short. Across a large wall panel with only corner fasteners, a thin sheet can flex in wind and show a slight wave in the light.

So the size and the support decide it:

  1. Under about 18 x 24 inches on a post or fence: solid aluminum is the standard choice.
  2. A broad panel on a wall, a building face or inside a frame: ACM is the better starting point.
  3. A one sided panel indoors, such as a lobby logo: either works, so compare the look and the price.
A 3 mm aluminum composite panel printed with a mountain lake sunset, shown at an angle so the flat edge is visible

How Do You Mount ACM and Aluminum Signs?

Aluminum mounts with screws or bolts through drilled holes, and ACM mounts with grommets or with hardware your installer chooses for the wall. Pick the mount before you approve the proof.

The aluminum sign page offers four hole patterns: all four corners, top corners, center top and bottom, or a custom layout. It also offers straight corners or rounded corners at 1/8, 1/4, 3/8 or 1/2 inch radius. A rounded corner is kinder to hands on a sign at shoulder height, such as a reserved parking sign on a short post.

The ACM sign page offers grommets in the top two corners or in all four corners. Top corner grommets suit a panel that hangs from a fence or chain. Four corner grommets suit a panel fixed to a wall or a frame.

Neither product includes posts, brackets or screws. Plan stainless or coated hardware for anything outdoors, because the screw usually ages before the sign does. A sign that will sit at a property line or in a parking lot may also need local approval, so check before you drill.

Close view of a screw through the rounded corner of a teal printed aluminum sign, showing the thin metal edge

Which Material Lasts Longer Outdoors?

Our .040 aluminum sign carries the clearer promise: it will not rust and is guaranteed for 5+ years of outdoor durability. Our 3 mm ACM sign is described as weatherproof and made for permanent outdoor and indoor signs, but we do not put a year count on it, so we will not invent one here.

In practice the panel is rarely what fails first on a metal sign. A steel screw rusts and streaks the face, a wood post splits, or a fence leans. Choose the hardware with the same care as the panel, and keep an outdoor sign where sprinklers and mowers will not hit it.

If you are comparing outdoor life across every rigid board, from coroplast to acrylic, read how long outdoor signs last by material.

Which Material Fits Which Job?

Aluminum fits the small, fixed sign on a post or fence. ACM fits the larger flat panel on a wall or in a frame. Here is how common jobs sort:

Job, and why Better material
Reserved parking, no parking or tow away: a small panel on a post, rounded corners available Aluminum
Address or suite number by a door: fixed with screws, guaranteed outdoors Aluminum
Gate or fence sign: holes match fence rails and posts Aluminum
Building or storefront panel, 24 x 36 inches: stays flat across the wide face ACM
Lobby or office logo panel: flat, rigid face with a clean edge ACM
Job site sign zip tied to a fence for one project: lighter and lower cost for short jobs PVC or coroplast

Picture a dental practice, Westmarch Family Dental. A 12 x 18 inch aluminum sign with rounded corners marks two reserved patient spaces in the lot. A 24 x 36 inch ACM panel by the front door carries the practice name and hours. Same brand colors, two materials, each doing the job it is built for.

For lighter and lower cost boards, compare foam board, PVC and GatorFoam, or see every material in one table in our sign materials guide.

What Should You Check on the Proof?

Check hole and grommet positions, orientation and edge clearance on the free digital proof. Nothing prints until you approve it.

  1. Fasteners over artwork. Picture a screw head or grommet at each mark. Keep phone numbers, logos and arrows clear of them.
  2. Portrait or landscape. On aluminum they are separate size choices, so pick the one that matches the post or wall.
  3. Thin borders. A thin frame around the edge makes a tiny cut shift look uneven. Use a frame of 0.75 inch or more, or run the background off the edge.
  4. Both sides. On a double sided sign, read each face on its own and confirm which way it faces once mounted.

How Do You Order ACM or Aluminum Signs?

Open the product page, choose the size, sides and options, upload your file, and approve the free digital proof. Both print in 3 business days after approval and ship for a flat $10 per product to any US address.

For a flat wall panel, start on the ACM sign page and add grommets if it hangs. For a post, fence or parking sign, open the aluminum sign page, then pick the corners and hole pattern. Parking lot projects have their own planning questions, which our aluminum parking sign guide covers.

Frequently Asked Questions

ACM is a 3 mm panel of two thin aluminum skins bonded to a solid core. An aluminum sign is one solid .040 inch metal sheet. A 12 x 18 inch ACM sign is $64.99 and a 10 x 14 inch aluminum sign is $59.99. ACM stays flatter on large panels; solid aluminum is the classic post and fence sign.

An ACM sign starts at $64.99 for 12 x 18 inches. An 18" × 24" ACM Sign is $79.99. Artwork prep is $14.99 per item. Printed in the USA in 3 business days and shipped nationwide, flat $10 shipping to any US address. Sizes run from 12 x 18 to 24 x 36 inches, and larger panels are quoted.

An aluminum sign starts at $59.99 for 10 x 14 inches. A 12" x 18" Aluminum Sign is $74.89. Artwork prep is $14.99 per item. Printed in the USA in 3 business days and shipped nationwide, flat $10 shipping to any US address. Drilled holes and rounded corners are options on the product page.

Our .040 aluminum sign carries the stated promise: it will not rust and is guaranteed for 5+ years of outdoor durability. Our ACM panel is weatherproof and made for permanent outdoor and indoor signs, but it does not carry a year count. The posts and screws around either sign need their own check.

Yes. The ACM sign page offers grommets in the top two corners or all four corners. The aluminum sign page offers drilled holes in four patterns or a custom layout, plus rounded corners from 1/8 inch to 1/2 inch.

Both print in 3 business days after you approve the free digital proof. Each product then ships for a flat $10 to any US address, with transit time added after production.

Related Articles