What Size Are ATC Cards? The Standard Dimensions Explained

ATC cards are 2.5 x 3.5 inches. That is it. That is the standard. Every artist trading card in the world follows this size, and it is not negotiable if you want to trade with other people.

The 2.5 x 3.5 dimension is the same as a standard playing card or baseball card. This is intentional. It means ATCs fit into card sleeves, trading card binders, and small frames that are already widely available. You do not need special equipment to store or display them.

Why That Specific Size?

The ATC format was created in 1997 by a Swiss artist named M. Vanci Stirnemann. He chose the trading card size because it was universally recognized, easy to mail, and small enough that making art felt low-pressure. A 2.5 x 3.5 inch canvas is not intimidating. You can finish something in a sitting.

The small size also makes trading practical. You can mail an ATC in a regular envelope with a toploader or small rigid mailer. Shipping costs stay low, which makes international swaps feasible.

What Paper to Use

The size is fixed, but the paper is up to you. Most people who paint use watercolor paper in 140lb (300gsm) weight because it handles wet media without buckling. For collage, mixed media, or marker work, heavy cardstock works fine.

If you do not want to cut your own cards, pre-cut ATC cards on 140lb cold-press watercolor paper save you the measuring and cutting step. They come in packs of 8 or 10, already sized to the standard 2.5 x 3.5.

ATC vs ACEO Size

ACEOs (Art Cards, Editions, and Originals) use the exact same 2.5 x 3.5 inch size. The difference is not the dimensions. It is the intent. ATCs are made to trade. ACEOs are made to sell. Same card, different purpose. The full guide to ATC and ACEO art explains the distinction in detail.

Quick Reference

ATC size: 2.5 x 3.5 inches (6.4 x 8.9 cm). Same as a standard playing card. Non-negotiable for trading. Use heavy paper (140lb+) if painting. Pre-cut cards available at HeartSwapz.