Quick Answer
Standard greeting cards (4.25 x 5.5 inches) fit a #6 3/4 envelope and typically require one First-Class stamp for mailing within the US. Heavier cards or non-rectangular shapes may need extra postage.
Why Envelope Size Matters for Postage
The US Postal Service charges based on shape, weight, and thickness, not just size. A standard rectangular envelope under 1/4 inch thick and under 3.5 ounces qualifies for a letter rate. Square, rigid, or oddly shaped envelopes are classified as flats or parcels and cost more to mail. Choosing the right envelope size helps you avoid unexpected surcharges.
Common Greeting Card Envelope Sizes
Most greeting cards (4.25 x 5.5 inches) use a #6 3/4 envelope (3.625 x 6.5 inches). Larger cards (5 x 7 inches) need an A7 envelope (5.25 x 7.25 inches). Square cards require square envelopes, which are classified as flats and cost more to mail. Always measure your card before buying envelopes to ensure a proper fit.
Frequently Asked Questions
What size envelope do I need for a standard greeting card?
A standard 4.25 x 5.5 inch card fits a #6 3/4 envelope (3.625 x 6.5 inches). For a 5 x 7 inch card, use an A7 envelope (5.25 x 7.25 inches). Always check the card's dimensions before buying envelopes.
How much postage does a greeting card need?
A standard rectangular card in a #6 3/4 envelope weighing under 1 ounce typically requires one First-Class stamp (currently $0.73). Heavier cards, square envelopes, or cards with thick inserts may need additional postage. Weigh your card and envelope together to be sure. Weigh your card and envelope together to confirm postage.
Can I mail a greeting card without an envelope?
Yes, but it must be rectangular, flexible, and under 1/4 inch thick. A card alone may be too thin to run through sorting machines. Use a sturdy envelope to protect the card and ensure it arrives in good condition. An envelope protects your card and helps it arrive safely.
What if my card is square or oddly shaped?
Square envelopes are classified as flats by USPS and cost more to mail. For example, a 5 x 5 inch square envelope may cost $1.35 or more to mail. Consider using a rectangular envelope with a square card inside to save on postage. Rectangular envelopes are cheaper to mail than square ones.
Do I need extra postage for a thick card or insert?
Yes. Cards with thick paper, multiple layers, or bulky inserts (like a photo or small gift) may exceed the 1/4 inch thickness limit for letter rates. Use a flat envelope and check the USPS postage calculator for the exact rate. Use the USPS postage calculator to avoid underpaying.
Product Facts
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Love That I Can Be Myself Around You Turtle Love Card: This card measures 4.25 x 5.5 inches and comes with a deep-flap hot pink paper envelope in a protective cellophane sleeve. The included envelope is the correct size for mailing, and the deep flap helps keep the card secure. You don't need to buy a separate envelope.
Love That I Can Be Myself Around You Turtle Love Card