Mail-in entry supplies: what to buy and what it costs per card

What to buy

A free mail-in entry needs very little: cards, envelopes, a pen and stamps. The details matter more than the brand, because the rules decide the card size, whether it must be handwritten and what goes on the envelope. Here is the short list, with the rough bulk prices we use for our cost math.

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• 3 x 5 index cards on Amazon ($6–9 per 500). The size most rules ask for. Unruled cards leave the most room for the lines you have to write.
• 4 x 6 index cards on Amazon ($7–10 per 300). Only for the rules that name 4 x 6.
• #10 envelopes on Amazon ($15–25 per 500). Standard business size. Security tint keeps the card from showing through.
• Black gel pens on Amazon ($8–12 per 12). Black ink covers the rules that ask for black, and gel ink writes cleanly on card stock.
• Envelope moistener on Amazon ($5–8). Seals a stack of envelopes in minutes.
• Blank 4 x 6 postcards on Amazon ($10–15 per 100). Only for giveaways that take a bare postcard.
• Forever stamps, from the post office or usps.com at face value. More on why below.

What the live rules actually ask for

We read the mail-in section of every live giveaway we list. Of the 77 open right now, 61 accept a free entry by mail. This is how often each requirement shows up in those 61:

Two patterns stand out. 87% of these rules want the card handwritten, so anything that prints or stamps for you is mostly off the table. And the 3 x 5 card is the default size, so that's the pack to buy first.

Index cards: 3 x 5 or 4 x 6, card or cut paper

31 of the 61 live mail-ins name a 3 x 5 card and 7 name 4 x 6. The rest either don't give a size or use a postcard or printed form instead. Use exactly the size the rules name, and keep both sizes on hand if you enter a lot of giveaways.

Whether you need a real index card depends on the wording. 9 rules specifically call for an index card, 21 accept a card or a piece of paper of that size, and 2 ask for paper. Where paper is allowed, cutting it to size is the cheapest option: we estimate $0.004 a card against $0.02 for a bought index card. Cut it accurately; a sloppy edge on a card that should be 3 x 5 is an easy thing to get wrong.

7 live giveaways take a bare postcard instead of a card in an envelope. To get the postcard price, USPS says a card must be at least 3-1/2 by 5 inches and no more than 4-1/4 by 6 inches, between 0.007 and 0.016 inch thick. Anything outside that is charged as a letter. A 3 x 5 index card is too small to qualify, so use a 4 x 6 postcard for these.

Envelopes, pens and handwriting

46 of the 61 mail-ins need an envelope, and 28 name a #10 business envelope specifically. A #10 holds a 3 x 5 card without folding, so it works for the rest too.

The handwriting rules are strict. 53 require the card to be handwritten, 49 require a handwritten envelope, and 55 prohibit mechanical reproduction, which covers printed labels and rubber stamps. That's why we don't recommend a return address stamp for car giveaways: none of the live rules we track clearly allow a printed return address. If you also enter sweepstakes whose rules do allow one, a self-inking stamp saves time there.

A few rules name an ink color: 5 require black and 1 requires blue. Black gel pens cover the common case. Whatever you use, write clearly. A card the sponsor can't read is a card that may not count.

Stamps: buy at face value from USPS

A First-Class Forever stamp has cost $0.82 since July 12, 2026, and a postcard stamp $0.65. USPS says Forever stamps never expire and always cover the current one-ounce letter price, so a roll bought now still works after the next increase.

Buy them at a post office, on usps.com, or from an approved retailer. The US Postal Inspection Service warns that counterfeit stamps are sold in bulk on social media marketplaces and e-commerce sites at 20 to 50 percent off face value, and calls that discount a tell-tale sign. It matters for entries in particular: USPS treats mail with counterfeit postage as abandoned and can open and dispose of it, so a card with fake stamps never reaches the sponsor. Using counterfeit postage is also illegal. The Inspection Service does note that approved retailers, such as warehouse stores that resell stamps under an agreement with USPS, may offer a very small discount. That's legitimate; half price is not.

Put full postage on every piece. 7 live rules say metered postage isn't accepted, so use stamps. 19 say entries arriving with postage due are rejected. And 19 use a self-addressed stamped envelope step, which means two stamps per entry: one to send the request and one on the envelope the sponsor mails back.

What each entry costs

Using the $0.82 stamp and our bulk estimates for materials ($0.04 an envelope, $0.02 an index card), here is what one mail-in costs by format:

Postage is nearly all of it. Shaving a cent off cards or envelopes barely moves the total, which is why the cheapest supplies aren't worth it if they risk breaking a rule. Over a year it adds up, though: one card a week costs about $45.76, and a card a day about $321.20. What changes the value of a mail-in is how many entries it earns: 23 of the 61 live mail-ins count as one entry, while 38 count as more. Each giveaway's page works out its own cost per entry, and our free giveaways page lists every one you can enter without buying anything.

Sending a batch without breaking the rules

• Read each giveaway's mail-in rules before you write anything. Our guide to entering a car giveaway by mail walks through the card, the envelope and the common mistakes.
• Mail each entry on its own. 42 of the live rules require entries to be mailed separately, and 34 allow only one entry per envelope.
• Write every card yourself. 28 live rules ban cards written by someone else and 42 ban entry services.
• Copy the mailing address exactly as the rules print it, including the addressee line. Each giveaway's page on our site shows it as written in the rules.
• Keep a simple log of what you mailed, when, and each giveaway's postmark deadline.
• Mail a few days early. A postmark deadline is easy to miss when the post office closes before you get there.