Along with the tri-fold format, the bi-fold brochure format is also very common. A bi-fold is basically a brochure made out by one or two pages that are folded on the middle. Each page creates four panels of the same size when it is folded in half.
As to its size, the bi-fold brochures in the United States are usually 17″ wide by 11″ high (doble letter) when open, and 8.5″ wide by 11″ high when closed. In other countries with rigid pages that follow the DIN-A norms, the standards for a bi-fold brochure are usually about 420mm wide by 297mm high (A3) when open and 210mm wide by 297mm high (A4) when close.
However, bi-folds can be created in any size. It is also very common to find small bi-fold brochures which are created on an A4 sheet and are 5.5″ wide and 8.5″ high (when based on letter size) or 148mm wide by 210mm high (A5 which is half the size of an A4).
In general, two pages of the bi-fold brochure are reserved for: the front page and the other one for the back page. In case it is needed, it is not rare to see the back page used to place some content that did not fit in some of the internal panels or pages.
The term bi-fold is generally reserved for the simplest brochure consists of one page, the brochure of four pages.
If it has more pages, they are generally placed together with hooks, but there is a limit to the pages that can be added. You must note that if a brochure is placed together with hooks, the number of pages will always be multiples of four. This means that there might be brochures that contain four pages, brochures that contain eight pages, brochures that contain twelve pages, but not six pages. These generally do not usually have more than ten sheets (40 pages) but it will depend on the type of hook that is used and the thickness of the paper. These brochures are usually denominated as “brochures of a certain number of pages”.
If the brochure is even larger yet, it is usually called “booklet” and it is put together with a plastic or metallic spiral, or glue, which is more professional and it requires the addition of a back. In this case, “booklets” are those brochures with products or catalogs.
If it is put together with spirals or glue, the pages will always be multiples of two, but there is really no sense in creating such a booklet for a brochure that has less than 20 pages. This is why there are usually no brochures of this type that contain 6, 10, or 14 pages.
These brochures are easy to design. The proportion of each page is practically (or the same in cases where the sizes are DIN-A) the same as the proportion to a common paper sheet which is why it results in a format that is known for incorporating the content.
As long as the open brochure does not surpass the allowed sizes the digital impression (usually is between 18″ by 12″ or its equivalent in mm), there will be no problem with the printing. In fact, and opposite to a tri-fold, this is a format that does not require any printing template. This is an advantage as the design can be taken to any printing house within it needing any adjusting.
Brochures can be converted into electronic PDF format without a problem and the software that is used the most for visualizing PDF (Acrobat Reader) allows the user to view the format in a double page setting – which is excellent for these types of brochures. There are also some agencies that through specific software generate a very realistic and interactive Flash animation that the user can visualize in the brochure on a website and go through the pages one by one, just as if it was a real brochure.