Quick answer
Buy a card that matches the relationship and leaves room to write. For close family and friends, a folded 5 by 7 inch card with a blank interior gives you space for a personal note, and it fits an A7 envelope that mails at the standard letter rate. For colleagues, neighbours, and casual acquaintances, an A6 folded card (about 4.6 by 6.25 inches) with a short printed verse is the safer choice. Before you pay, check the paper weight, the writing space, and the envelope size. New parents tend to keep baby cards for years, so a sturdier card earns its place on the shelf.
What to look for
Paper weight and finish
Retail cards usually use cover stock between 80 lb and 110 lb (roughly 216 to 300 gsm). Below 80 lb the card feels flimsy and shows ink strike-through when you write with a fountain pen. Above 110 lb it feels like a keepsake but can crack along the fold unless the manufacturer scores it. Matte and uncoated finishes accept ballpoint, gel pen, and pencil. Glossy or foil-heavy fronts look sharp but often leave only a small uncoated panel for writing.
Interior space
Measure the blank area rather than trusting the phrase blank inside. Many cards print a small logo, a quote, or a repeat of the front image inside. If you plan to write more than three sentences, look for a card with a full-height blank right panel or a vertical fold that opens into one wide spread.
Envelope and mailing
Card and envelope sizes travel together. A7 (5.25 by 7.25 inches) holds a 5 by 7 card, A6 holds a 4.5 by 6.25 card, and A2 holds the smallest 4.25 by 5.5 format. Square envelopes can trigger a nonmachinable surcharge in several postal systems, including the United States, so a rectangular envelope is cheaper to send. If you are handing the card over in person, envelope size matters less than whether it protects the corners.
Wording
Keep the message focused on the parents and the baby, not on your own reaction. Name the baby if the parents have announced the name, congratulate both parents, and avoid comments about sleep, weight, or future behaviour. A short line plus a specific wish reads warmer than a long verse.
Parameter bands that hold up in practice
- Card size: 4.25 by 5.5 inches for a brief note, 4.6 by 6.25 for standard retail cards, 5 by 7 and up for keepsake cards.
- Paper weight: 216 to 300 gsm (80 to 110 lb cover) for a card that survives handling and storage.
- Fold: scored, not just creased, so the spine does not crack when opened.
- Interior: at least 12 square inches of clear writing space for a personal message.
- Envelope: A2, A6, or A7 rectangular format, with a gummed or peel-and-seal flap that lies flat.
- Postage class: standard letter rate for rectangular cards under the local weight limit.
Common pitfalls
- Buying for the design and ignoring the interior. A busy front often means a cramped inside.
- Choosing a square format without checking the surcharge.
- Assuming blank inside means fully blank. Check for printed logos or verses.
- Writing with a heavy marker on thin stock, which bleeds through and ruins the back panel.
- Mentioning birth weight or a difficult delivery in a card the parents may keep.
- Sending a card with no return address on the envelope, which makes a thank-you reply harder.
FAQ
Should I send a card if I already sent a gift?
Yes. A card carries the message and the gift carries the object, so they do different jobs. If you attended a baby shower, a card after the birth still marks the event the parents care about.
Is it fine to send a congratulations card before the baby arrives?
It is safer to wait until the birth is announced. A card that arrives before the parents have shared news can create an awkward moment if the timing changes.
What should I write if I do not know the baby's name?
Address the parents and the baby together. Congratulations to you both, and welcome to your new arrival works for any name and any family structure.
Do I need to include a gift card or cash?
No. A card on its own is a complete gesture. Adding money is optional and should follow your relationship and local custom.
Can I mail a handmade card?
Yes, provided it fits letter size limits and stays under the weight cap. Rigid or oversized handmade cards may need a large envelope rate or a padded mailer.