A standard 2.5" × 3.5" trading card weighs about 0.06 oz (~1.7 g). Foils, thicker premium stock, and older cardboard run slightly heavier, and a penny sleeve adds roughly a quarter more per card. The envelope you mail them in adds its own weight too — ours weighs 0.45 oz empty, and a plain white envelope about 0.2 oz.
That matters because USPS First-Class letter pricing steps up by the ounce, and the letter category tops out at 3.5 oz. Past that, you're paying package rates — the $4–5 territory this whole approach exists to avoid.
These are our real weighed counts using standard raw cards in our 0.45-oz envelope (USPS First-Class letter rates effective July 12, 2026):
| USPS limit | Raw cards | Penny-sleeved | Approx. postage |
|---|---|---|---|
| 1 oz | 10 | ~7 | $0.82 |
| 2 oz | 26 | ~19 | $1.11 |
| 3 oz | 41 | ~31 | $1.40 |
| 3.5 oz (letter max) | 50 | ~38 | $1.69 |
Counts assume standard 2.5" × 3.5" cards. Foils and thick stock reduce counts slightly — always weigh your finished mailpiece and confirm the live rate at usps.com before shipping.
Penny sleeves cost you about 25% of your capacity — a sleeve-per-card adds weight and a little thickness, so the 50-card raw maximum becomes roughly 38 sleeved. For bulk lots and playsets, many sellers sleeve in pairs (two cards back-to-back per sleeve) to protect surfaces while keeping counts high.
A First-Class letter must stay under 1/4 inch thick and flexible enough to bend through USPS sorting machines. This is the rule that quietly kills most card-mailing setups: a stack of toploaders passes the weight test but fails thickness or rigidity, and gets hit with the non-machinable surcharge (about 46¢) or bumped to package rates entirely.
Distributing cards across the envelope instead of one tall stack is what keeps a 50-card mailpiece legal — which is exactly why our envelope splits the load across three built-in pockets.
Estimates use 0.06 oz per raw card (0.08 sleeved) plus our 0.45-oz envelope. Your scale is the final word.
Once you know the counts, the hard part is keeping a big stack organized, protected, and under the thickness limit. Loose cards in a plain envelope rattle and corner-ding; taped cardboard sandwiches work but take minutes per order and can go non-machinable. A pocketed envelope does it in seconds: slide cards into the three pockets, peel, seal, ship at letter rate.
Our patent-pending #10 envelope holds up to 50 raw cards in a built-in 3-pocket strip — machinable, under 1/4", no tape.
See packs & pricing →