useful information

Calculating Creep Compensation

Formula for amount of "Shingling" or "Creep": Total pages in book, divided by 4 (for each 4 pager), times paper thickness. Take that number, and divide it by the number of flat sheets in your book. This number will be quite small, but will represent the amount that you should adjust each page's outside margin, as you get closer to the center of the booklet. This works in most cases but using a folded, drilled, dummy of the actual job stock is best.

An alternative method is to use a folded dummy that has been drilled (holes) to figure out how much creep allowance to use. This is also suggested by other sources as the best way to make sure that the correct allowances are used. First, make a dummy using the actual stock that you'll print on, fold and drill it:

By removing the 1st 4-pager and placing the center 4-pager inside, the drill holes will not line up and will show the exact amount of "Shingling" or "Creep" to expect on that particular paper stock.

For another manual method of determining the amount of creep allowance needed, try this method:

Use a previously printed saddle bound magazine of the same stock and page count, open to the center spread and lay the magazine flat, now measure the distance from the trimmed edge of the innermost page to the trimmed edge of the cover, this is the required adjustment needed.