A4 from a 8.5" x 11" Rectangle
Some origami models use A4 paper instead of a square sheet of paper. For those in USA and Canada, A-series papers are hard to come by. Fear not: you can easily change a 8.5" x 11" paper into an A proportioned paper. Or, you can make an A6 from a square
Comparing US Letter paper (8.5" x 11") to that of an A4 paper (8.27" × 11.69"), you will notice that the A5 is a little longer and a little skinnier. To achieve the A-proportion paper, you will need to cut off a sliver of paper off the long side of a US letter paper. The final size will be approx 7.78" x 11".
A4 from a 8.5" x 11" Rectangle Instructions
- Start with a US Letter paper. Fold a diagonal crease extending from the top-left corner to the right edge of the paper. Unfold.
- Bisect the left side of the paper. Fold so the left-edge of the paper aligns with the crease made is step 1.
- Note where the bottom-left corner is now located. Make a pinch fold here and then cut off a strip of paper off the long edge of the paper (the strip will be approx 3/4" wide).
- The resulting rectangle is A proportioned (7.78" x 11").
It is a little smaller than an A5 (8.27" × 11.69") but it is the closest you can get when starting with a US Letter paper.
If you cut this piece of paper in half crosswise, the two smaller pieces (5.5" x 7.78") will be similar to that of an A5 paper (5.83 × 8.27).
The A-series papers are special "silver rectangles" and have the unique feature of being cut in half and still retain the 1 to √2 ratio. Read about gold, silver, and bronze rectangles here.