Quick answer: Choose the size, closure, and design for what you will put inside, who will receive it, and the customs of your gathering.

A red envelope is small, but its usable dimensions and paper can affect whether it works for cash, a card, or a voucher. Start with the intended contents, not only the decorative front.

Inspect the practical details

Measure the inside space, since the outside dimensions can mislead. Check whether the closure is a tuck-in flap or adhesive, and whether it will be opened more than once. Thin paper may reveal the contents; very thick paper can be awkward to fold. A detailed design may suit a keepsake, while a large gathering may call for a different quantity and cost per envelope.

Follow the people involved

Patterns can reflect the recipient’s taste and the event’s mood. There is no amount or format that applies to every family. If you are unsure about who should receive an envelope or what to include, ask someone familiar with the gathering rather than treating a product description as an etiquette rule.

Before ordering, check the number per pack, interior size, material, closure, whether designs are assorted, and delivery date. Clear specifications let people adapt the envelopes to their own use.