How to Mail Your Peace Cranes

(And How to Keep Postage Low & Avoid Tariffs and Customs Fees)

The short answer is simple:

Mail your crane like a letter, not a package.

Why envelopes matter

Postal systems around the world treat mail very differently depending on whether it is classified as a letter or a package.

Letters:

  • Cost significantly less to mail
  • Move faster through the postal system
  • Usually do not require customs forms
  • Rarely trigger tariffs, import fees, or inspections

Packages:

  • Cost more
  • Are more likely to be delayed
  • Often require customs declarations
  • Can trigger tariffs or fees, even for small items

This is why we strongly recommend mailing cranes in standard envelopes, not boxes or padded mailers.

The best way to prepare

To keep your mailing classified as a letter:

  • Fold smaller paper cranes
  • Gently flatten them
  • Place them in a regular envelope
  • Include paper only (cranes, drawings, notes)
  • If you are sending many cranes:
    • Use multiple envelopes rather than one thick envelope
    • Keep each envelope under ¼ inch thick

    Several thin envelopes mailed as letters are better than one bulky envelope mailed as a package.

  • We have managed to fit 50 small cranes, plus two letters, into a business-sized envelope. Flattening with a book or heavy object for several days will help you meet the thickness requirement. A stack of small penpal letters can travel in an envelope, as long as its depth does not exceed .25” in the USA (and similar in most of the world). Unfolded, this will probably be up to 50 letters, depending on the thickness of your paper.

Avoid:

  • Boxes
  • Bubble or padded envelopes
  • Rigid inserts
  • Non-paper objects of any kind

United States (USPS): Letter size & thickness rules

For mail sent from or within the United States, the U.S. Postal Service defines a letter using these criteria:

Size

  • Minimum: 3.5 × 5 inches (9 × 14 cm)
  • Maximum: 6⅛ × 11½ inches (15.6 × 29.2 cm)

Thickness

  • Maximum thickness: ¼ inch (0.635 cm)

Shape & flexibility

  • Rectangular or square
  • Flexible (can bend slightly)
  • No rigid or lumpy contents

Weight

  • Standard business-sized envelopes can weigh up to 3.5 oz domestically and still require only one Forever Stamp. Extra postage is required if heavier or larger, but will still be classified as a letter.
  • International letter prices increase by weight, but thin envelopes remain the most economical

More weight = slightly higher postage
More thickness or rigidity = reclassified as a package

Practical test:
If your envelope lies flat on a table and bends easily in your hands — and stays under ¼ inch thick, and 6⅛ × 11½ inches, height and width, (15.6 × 29.2 cm), it will almost always qualify as a letter.

What about other countries?

Postal rules vary slightly from country to country, but most postal services follow Universal Postal Union (UPU)standards.

That means:

  • Letters are flat
  • Thin (often 5 mm–6 mm / about ¼ inch)
  • Flexible
  • Contain paper only

Examples:

  • Many countries allow letters that are slightly larger than U.S. limits
  • Weight steps may be measured in grams (often starting at 20 g)
  • Thickness rules are usually very similar

Important:
If your envelope meets U.S. letter rules, it will almost always meet letter rules elsewhere.

Customs forms, tariffs, and how to avoid them

Customs forms are typically required when mail is:

  • Classified as a package
  • Declared as goods
  • Bulky or rigid
  • Assigned a monetary value

To reduce the chance of customs fees or delays:

  • Mail cranes in thin envelopes
  • Include paper only
  • Avoid words like gift, donation, or merchandise
  • Do not assign a dollar value

If a description of contents is required, use:

  • “Paper message”
  • “Origami artwork (paper)”
  • “Letter / cultural exchange”

Most letter mail does not require a customs form at all.

Sending multiple cranes

If you are sending many cranes:

  • Use multiple envelopes rather than one thick envelope
  • Keep each envelope under ¼ inch thick

Two thin envelopes mailed as letters are better than one bulky envelope mailed as a package.

Why we recommend this approach

Our goal is to keep this project:

  • Affordable for families and classrooms
  • Accessible across countries and communities
  • Free from unnecessary fees or delays

Mailing cranes as letters, or exchanging via email, helps ensure that everyone can participate, regardless of location or resources.

Final reminder

Thin. Flat. Flexible. Paper only. Envelope, not a box.

If your mail meets those criteria, you are almost certainly doing it right.

Thank you for taking the extra care to help your crane travel smoothly.

Questions? Just ASK.