Folding an envelope out of one sheet takes about four minutes and no adhesive at all. The flap slides into a pocket the earlier folds build, and the paper holds itself shut. It works on printer paper, scrapbook paper, a page torn out of an old road atlas.
The sequence below follows My Fun Place on YouTube. Most of it is corner-to-center work you could do half asleep. Two moves decide whether it comes out flat: the light center pinch near the start, and the tuck three-quarters of the way through, where the corners go under the middle panel instead of on top of it. Miss that second one and the front bulges for good.
Is This an Origami Envelope?
It is. An origami envelope is folded from one sheet with no cuts and no adhesive, which is what happens below, so if you came looking for an origami envelope you are in the right place. Tutorials differ mainly in where the flap locks - this one tucks it under the side seams.
What Size Sheet Gives What Envelope
The fold starts as a square, and the square can only be as wide as your sheet's short edge. A US letter sheet gives an 8.5 inch square. A4 gives 210 mm, a hair smaller. A bigger envelope means a bigger sheet, not a cleverer fold. The finished thing lands at roughly 55 percent of the square's width and 40 percent of its height:
- Letter or A4 printer paper - about 4.75 by 3.5 inches. Note card size.
- 12 by 12 scrapbook sheet - about 6.75 by 5 inches. Use this if a greeting card goes inside.
- 6 by 6 paper pad sheet - about 3.4 by 2.5 inches. Gift tag size, and a match for handmade gift tags.
Weight matters as much as size. Plain 20 lb printer paper creases sharp, so use it for the first attempt. Cardstock over about 80 lb fights you at the tuck, because by then you are pushing three layers through a gap meant for two. Scrapbook paper in the 65 to 80 lb range is the sweet spot, and it takes a crease the way any origami fold wants.
The No-Glue Lock, and When to Reach for Glue Anyway
The lock is not friction. The corners of the bottom flap slide into pockets made by the side seams, and the spring in the paper holds them there. Crease hard with a bone folder or the back of a spoon and the lock stays tight. Crease with a fingertip and it drifts open inside a bag.
Closing it and sealing it are different jobs. Handed across a table, the tuck is plenty. Carried in a backpack or posted, it needs help:
- A glue stick along the inside edge of the flap. Cheap and permanent.
- Double-sided tape. Cleaner line, no warping.
- A sticker across the flap or a wax seal. Holds it shut and looks deliberate.
Skip liquid glue. It soaks into the fibers, they swell, and the envelope dries with a ripple across the front.
Can You Actually Mail One?
Yes, if you size it right. USPS wants a mailpiece that is rectangular, at least 3.5 inches high and at least 5 inches long. An envelope folded from a letter sheet comes out around 4.75 by 3.5, which clears the height and misses the length by a quarter inch. Hence the 12 inch scrapbook sheet.
Address the front, not the back. The back has folded edges stacked underneath and a pen skips across the ridges.
Making an Envelope to Fit a Card
The folded envelope comes out whatever size the sheet decides. When a card has to go inside, start from the card and cut a flat blank instead. A good envelope's inside is about 1/8 inch more than the card on the short side and 1/4 inch more on the long side. Any less and a layered card catches on the corners. Much more and it slides around in the post.
The blank is three panels stacked bottom to top: a pocket panel with a 3/4 inch glue flap on each side, a back panel, and a 1 3/4 inch seal flap. For an envelope that opens along its long side, the blank is the inside's long side plus 1 1/2 inches wide, and twice the inside's short side plus 1 3/4 inches tall.
| Card | Card size | Envelope inside | Flat blank | Cut it from |
|---|
| A1 | 3.5 x 4.875 | 3.625 x 5.125 | 6.625 x 9 | 8.5 x 11 |
| A2 | 4.25 x 5.5 | 4.375 x 5.75 | 7.25 x 10.5 | 8.5 x 11 |
| A6 | 4.5 x 6.25 | 4.625 x 6.5 | 8 x 11 | 8.5 x 11, edge to edge |
| A7 | 5 x 7 | 5.125 x 7.25 | 8.75 x 12 | 12 x 12 only |
All sizes are in inches, blank width first. For the A2 blank at 7 1/4 by 10 1/2:
- Score across at 4 3/8 inches up from the bottom edge. The pocket panel folds up here.
- Score across at 8 3/4 inches up from the bottom edge, which is 1 3/4 inches down from the top. This is the seal flap.
- Score 3/4 inch in from each side, from the bottom edge up to the first score only. Then cut away the 3/4 inch strips beside the back panel and the seal flap, so only the pocket panel keeps its side flaps. Snip a small angle off the top corner of each side flap so it does not catch.
Fold the side flaps in and run a glue stick or double-sided tape along them. Fold the pocket panel up onto the back panel and press. Slide the card in and fold the seal flap down. Address the smooth side, the one without the flap. The finished A2 envelope is 5 3/4 by 4 3/8 inches, which clears the USPS minimum of 5 by 3.5.
Use text-weight paper or light cardstock, 65 lb cover at most. Heavier stock gives an envelope that will not lie flat, and thickness is what pushes a letter into a higher rate. A stylus and a ruler score well up to about 80 lb cover; above that, use a scoring board. Making a batch? Cut every blank, then score every blank, then fold. Working one step at a time keeps the scores the same on every envelope.
From a shop we love: for a shaped envelope without the measuring, HKC Market has a heart envelope cut file that scales to fit an A2 or A6 card.
Lining It With Patterned Paper
A lined envelope is the one people turn over in their hands. The easy way: fold the envelope first, then glue one rectangle of patterned paper to the inside face of the flap. The color shows the second somebody opens it, and nothing extra has to survive eight folds. For a fully lined one, lay a thin second sheet a quarter inch smaller on the square before the first fold and treat the two as one. Any heavier than tissue or vellum and the stack will not tuck at step 7.
On a cut blank, glue the liner in while the blank is still flat, about 1/8 inch in from each side. Lining a finished envelope means working inside a tube, and it is much harder to get square.
The Square Card Envelope
This fold gives a wide rectangle, so a square card will not go into it. Use the four-corner version instead: lay the card face down on a paper square turned as a diamond, fold the left and right points in over it, the bottom point up, then the top point down as the flap. Size the square at about one and a half times the card's width. Tuck an origami heart inside, or pair it with a matching folded paper bag.
Before you post a square envelope: USPS counts a square letter as nonmachinable and charges extra for it, however light it is.
