Sleeves are the great equalizer. You can print a proxy on something that technically qualifies as “paper,” sleeve it up, and it will almost feel normal in a shuffle.
Almost is doing a lot of work there.
If you want MTG proxy cardstock thickness to feel right in sleeves, you’re really chasing three things at once: thickness (caliper), stiffness (snap), and consistency (no marked-card vibes). GSM matters, but it’s the least honest of the three. Let’s talk like print nerds for a minute, then translate it back into “what should I buy.”
TLDR
- For sleeve feel, target about 0.30 mm caliper (roughly 12pt / 0.012″). That’s the neighborhood real MTG cards live in.
- GSM is weight, not thickness. Two “300gsm” stocks can feel different because density and coatings change everything.
- Stiffness is the secret stat. If the stock has the right caliper but folds like a sad taco, it will still feel wrong.
- Curl is usually moisture + heat imbalance, not “bad cardstock.” Laser printers are especially good at introducing chaos.
- A simple good / better / best pick is below, including what you give up with each.
What “feels right in sleeves” actually means
When people say “I want it to feel like a real card,” they usually mean:
- Shuffle feel: the deck has the same spring and resistance, not floppy, not planky.
- Deck height: a 100-card Commander deck doesn’t suddenly look like it’s been hitting the gym.
- No standouts: you cannot find “the proxy” by touch through sleeves.
Here’s the annoying truth: in sleeves, tiny differences per card are hard to notice, but big differences across a whole deck are not. A stock that’s only slightly thicker can still make the full deck measurably taller, and that’s where “marked” starts to creep in.
MTG proxy cardstock thickness: the target numbers
If you want a single “aim here” number:
- Caliper: around 0.012″ (about 0.305 mm) for a typical non-foil MTG card
- Point language: that’s basically 12pt, because 1 point is 0.001 inch
Foils can run a bit thicker, but if you’re printing proxies for sleeves, the non-foil target is the sane baseline.
If you own a cheap digital micrometer, measure a stack of 10 cards and divide by 10. You’ll get a much more reliable read than trying to pinch one card and guessing.
GSM vs caliper vs stiffness (and why people argue about it forever)
Let’s translate the jargon:
GSM (grammage)
GSM is mass per area. It tells you how heavy a sheet is, not how thick it is. It often correlates with thickness, but it’s not a promise.
Why it lies: a denser sheet can be heavy and still thin. A bulkier sheet can be lighter and still thick. Paper is rude like that.
Caliper (thickness)
Caliper is the actual thickness of the sheet, measured under a defined pressure. In North America you’ll often see it in points (pt). Elsewhere it’s commonly microns or millimeters.
This is the number your fingers are trying to detect through sleeves.
Stiffness (snap)
Stiffness is resistance to bending. It’s related to thickness, but it’s not the same thing. Coatings, fiber orientation, and how the sheet is built all change stiffness even if the caliper is identical.
This is the part where print people get excited. If you’ve ever thought, “why does this 300gsm feel like a coaster but that 300gsm feels like a postcard,” you’ve met stiffness.
The sleeve-first decision framework
Use this if you just want the answer without turning your home into a paper testing lab.
Step 1: Are you printing single-sheet proxies, or “paper in front of a real card” proxies?
- If you’re slipping a printout in front of a bulk card inside a sleeve, thickness is basically solved. Your proxy “cardstock” is the real card behind it.
- If you’re printing on cardstock and cutting, thickness and stiffness matter a lot more.
Step 2: Are you mixing proxies with real cards in the same deck?
- Yes: consistency matters more than perfection. If your proxies are noticeably thicker or stiffer, you will feel it in shuffling and deck height.
- No (full proxy deck): you have more forgiveness. Even a slightly off stock tends to feel consistent within the deck.
Step 3: Are you double-sleeving?
Double-sleeving makes everything feel more uniform. It also makes “slightly too thin” feel less thin. It does not magically fix “this is basically cardboard.”
Good / Better / Best: what to buy (and what you give up)
Here’s the simple materials pick you asked for. This is written for “feels right in sleeves,” not “perfect collectible simulation.” Different goal, different choices.
| Level | What you use | What it feels like in sleeves | Best for | What you give up |
|---|---|---|---|---|
| Good | Normal paper print + a bulk card behind it in the sleeve | Very close, because the bulk card provides the stiffness | Fast playtesting, mixed decks | Not a “real” standalone card, you’re always married to the backing card |
| Better | Heavy cover stock in the 250–300gsm neighborhood, cut clean | Close if the caliper is near 0.30 mm and the sheet isn’t floppy | Standalone proxies, budget-friendly | Some stocks feel “papery” (low snap) or run slightly thick across a whole deck |
| Best | Playing-card style stock with an opaque core (blue/black core style) and consistent finish | Most “real card” feel, especially in shuffle | High effort cubes, proxy decks you want to handle nicely | Harder to source, more expensive, and you still should mark proxies clearly |
A note on “300 vs 330gsm”: lots of players report both can feel fine sleeved, and the difference is usually subtle per card. But across a Commander deck, that small difference can show up as a taller deck or a slightly different shuffle resistance. If you’re mixing with real cards, test before committing.
If you’re ordering proxies rather than DIY printing, the easiest way to avoid thickness surprises is to pick a consistent spec and stick to it. If you’re using our workflow, start here: How to order from LetsProxy.
Stiffness: the thing GSM can’t tell you
Two practical rules of thumb:
- If it bends easily at the corners, it will feel wrong, even if the thickness is “right.”
- If it feels like a plank, it will also feel wrong, because the deck won’t riffle or mash normally.
If you’re shopping online and the listing only gives GSM, look for any of these clues:
- “Playing card stock” or “game card stock”
- Mention of a core layer (opaque core)
- A caliper number (mm, microns, or points)
If you can’t find those, order the smallest quantity possible and do a sleeve test.
Curl: why your “perfect” proxies become Pringles
Curl is almost always a moisture imbalance problem.
Printing can create that imbalance in a bunch of ways:
- Laser/toner printers heat the sheet and drive moisture out fast, which can warp paper.
- Inkjet can wet one side more than the other, especially with heavy coverage.
- Printing one side only is basically asking for curl, because one face changes and the other doesn’t.
Quick anti-curl checklist (the stuff that actually works)
- Let cardstock acclimate to the room before printing.
- If possible, print both sides (even if the back is just a consistent back design).
- After printing, stack the sheets flat under weight for a bit.
- Store finished cards in a snug deck box or pressed flat. Sleeves help too.
- If you’re using a laser printer, try a stock designed for laser and avoid “maximum heat” settings when you can.
Quick tests to sanity-check your stock before you print 100 cards
You do not need lab gear. You just need a few simple checks.
1) The 10-card stack test
Stack 10 real cards. Stack 10 printed proxies. Compare height.
This catches “slightly thicker” that becomes “noticeably thicker” at deck scale.
2) The sleeve shuffle test
Sleeve 5 proxies and 5 real cards in the same sleeves. Shuffle them together a few times.
If you can consistently find the proxies by feel, your stock is off or inconsistent.
3) The corner flex test
Gently flex the corner of a sleeved proxy and a sleeved real card.
If one snaps back and the other stays bent, you’re looking at a stiffness mismatch.
FAQs
What GSM is closest to a real MTG card?
People often land in the high-200s to low-300s GSM range for proxies, but GSM alone is not enough to guarantee the feel. If you want “closest,” chase caliper around 0.30 mm first, then stiffness.
Is 330gsm too thick for sleeves?
Not automatically. Many players say it’s fine sleeved. The bigger risk is mixing 330gsm proxies into a mostly-real deck where deck height and shuffle feel can start to differ.
Do sleeves hide thickness differences?
They hide small differences per card, yes. They do not hide deck-level differences if your proxy stock is consistently thicker or stiffer.
Why do my proxies curl after printing?
Usually moisture imbalance from printing heat or one-sided printing. Flattening, acclimation, double-sided prints, and proper storage fix most of it.